PC Engineering

PCENGINEERING

(PCE-514)

PC ENGINEERING

Copyright ©CMS INSTITUTE, 2012

All rights reserved. No part of this publication may be reproduced, storedin a retrieval system, or transmitted, in any form or by any means,electronic, mechanical, photocopying, recording or otherwise without theprior permission of Programme Director, CMS COMPUTER INSTITUTE.

This book has been authored by the CMS INSTITUTE faculty group,solely for the purpose of using its contents as course material forworkshops conducted by and at the CMS COMPUTER INSTITUTEeducation centre.

PC ENGINEERING

CONTENTS

1. Electrical and Electronic Concepts 12. Basic Numbering Systems 53. Introduction to PC 134. Introduction to Operating System 175. Disk Operating System & Commands 216. Microsoft Windows Vista 357. Getting Familiar with the PC 798. Booting Sequence 899. Serial, Parallel, PS/2 & USB Interface 9510. Memory 10511. Processor 11912. Motherboard 12913. Floppy Disk Drive 15714. Hard Disk Drive 16515. Optical Storage Devices 19916. SMPS 22717. UPS 23918. Computer Mouse 24719. Keyboard 25320. Scanner 26121. Printer 26922. Display Interfaces & Monitor 29123. Multimedia 30924. Modem 32525. Backup Devices 33726. Viruses 34927. Laptop & Palmtop Computers 36928. Installation of Windows 98 SE 38129. Managing Application on Windows 98 SE 40130. PC Assembling 40931. Troubleshooting 425

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PC ENGINEERING

LAB EXERCISES

2.1 Conversion between Different Number Systems 11

5.1 Basic DOS Commands 34

6.1 Microsoft Windows Vista Operation 78

7.1 Identification of Backpanel Connectors 88

9.1 Identification of Serial Parallel & SCSI Ports 104

10.1 Identification of different types of Memory Modules 118

12.1 Motherboard Slot Identification and CMOS Settings 156

14.1 Identification of HDD Parts 194

14.2 Partitioning using Disk Part and Formatting the Hard disk 196

14.3 Using PQ Magic on a Hard Disk 196

14.4 Backing Up and Restoring the MBR of the Hard disk 196

14.5 Using Norton Ghost for Imaging of a Hard disk 196

15.1 Identification of Optical Storage Device Parts 226

16.1 SMPS Connector Identification 238

18.1 Mouse Button Options and Parts Identification 252

19.1 Keyboard Shortcuts 260

20.1 Scanning through Flatbed Scanner 267

21.1 Printing with Different Printers 289

23.1 Using Multimedia with Media Player 323

25.1 Backup Data on Backup Devices 347

26.1 Virus Scanning Using Anti-Virus Software 360

28.1 Windows VISTA Installation 400

29.1 Installing Different Application in Windows VISTA 408

Electrical and Electronic Concepts

1

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PowerThe energy or power to drive a computer is derived from electricity. Whetherit uses 110 volts alternating current (AC), the U.S. standard; 220 volts AC, theEuropean standard; or direct current (DC) from a battery, a computer is uselesswithout a steady, reliable source of power. When we encounter problems witha computer, it is crucial to be able to test the entire power system. This lessoncovers the basics of power and electricity.

Understanding Electricity and Electrical EnergyWhat is electricity? The meaning of the word varies with the user. Electricity tophysicists is the primal property of nature, and they call the power deliveredat the wall socket and stored in batteries electrical energy. Most people,including computer technicians, are less fussy, often using the term electricityto refer to both:

• The form of energy associated with moving electrons and protons

• The energy made available by the flow of electric charge through aconductor

Some Definitions

• Electricity: The form of energy associated with charged particles, usuallyelectrons.

• Electric charge: When charged particles move in tandem, they generatefields, producing energy.

• Electrical circuit: The path taken by an electrical charge.

• Electric current: When an electric charge is carried, or flows through aconductor (like wires), it is known as a current. A current-carrying wire isa form of electromagnet. Electric current is also known as electron flow.

• Power: The rate at which an amount of energy is used to accomplish work.Electrical power is measured in watts, which is determined by multiplyingvoltage by current.

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Electrical and ElectronicConcepts


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• Conductors: Materials that can carry an electrical current. Most conductorsare metals.

• Resistance: A quality of some materials that allows them to slow the speedof an electrical current, producing heat, and sometimes light, in theprocess.

• Insulators: Materials that prevent or retard the electrical current of electrons.

• Ampere: A measurement of current strength, equal to 1 coulomb per sec.

• Ohm: A unit of electrical resistance. Ohm's law states that voltage is equalto the product of the current times the resistance, or voltage = current ×resistance.

• Volt: The unit of electromotive force, or potential energy, that, whensteadily applied against a resistance of 1 ohm, produces a current of 1ampere.

• Voltage: The potential energy of a circuit.

Personal Computers and Electrical PowerThat personal computers (PCs) use electrical power to operate is no surprise,even to the casual user. The technician must understand the different types ofelectrical energy and how they work inside the PC. A PC's electrical power cancome from a wall outlet, in the form of AC, or from a battery in the form ofDC.

AC PowerAC power is what most people think of as electricity. It comes from the walland powers most of our lights and household appliances.

AC power is man-made, using generators. As the wire coil inside the generatorrotates, it passes by each pole of unit magnet(s) producing an electric current.When it passes the opposite pole, the current reverses, or alternates, thedirection of flow (see Fig. 1.1). The number of revolutions made by thegenerator per minute is called its frequency. In the United States, powercompanies run their systems at 60 turns per second to produce a high-voltage,60 Hz (cycles per second) AC as they rotate, while in India it is 50Hz. The power

system drops the voltage in stages beforeit is connected to the consumer's home orbusiness.

The power company delivers AC power toour homes or businesses with three wires.Two of the wires are hot, meaning that theycarry a charge. One, the bare wire that runs

from the breaker box to the power pole, is neutral. The measured voltage

©CMS INSTITUTE 2012

Fig. 1.1 Flow of electrons


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between the two hot wires is between 220 and 240volts AC (VAC), and the measured voltage betweeneither of the hot wires and the neutral wire is between110 and 120 VAC. These voltages, which are callednominal voltages, can vary by plus or minus (±) 10percent (see Fig. 1.2).

Typical electrical outlets are connected between one ofthe hot wires and the neutral wire. These outlets areusually three-prong connections. The smaller

rectangular hole is the hot, the larger rectangular hole is the neutral, and thesmall round hole is called the ground. The ground wire is used as a safetywire. In the event of a short circuit, a large flow of current (amps) is discharged

all at one time. This short, strong flow of current will burnout circuits unless it can be safely sent somewhere else.Electricity will always seek the path of least resistance toground. By providing this wire, a short circuit will cause lessdamage by providing a path for safe dissipation of thecurrent. To provide a safe working environment for thecomputer and yourself, make sure that the ground wire isproperly installed.

Older structures might have two-wire electrical outletswithout the ground wire. An electrical outlet without

grounded plugs and the third ground wire is unacceptable for use with acomputer (see Fig. 1.3). An extension cord without a ground wire is alsounacceptable.

CAUTION: A short circuit can cause physical damage to equipment andpersonnel. It can cause a fire, component damage, permanent disability, oreven death. The ground plug provides a direct connection to ground, givingthe electricity an alternate path away from equipment and people.

DC PowerAC is used for transporting low-cost power to end users. However, a computer'selectronic components won't run on AC power—they need a steady stream of

DC. The PC's power supply performs severaltasks, but the main function is to convert ACinto DC. A computer's power supplycombines two components to handle thisjob: a step-down transformer and an AC/DC converter. The AC adapters used forlaptop computers, many low-cost ink-jet

Fig. 1.2 AC Volts


Fig. 1.3 The proper type ofoutlet includes a ground



Fig. 1.4 DC power


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printers, and many other consumer electronics do the samething—turn AC into lower voltage DC.

As we have seen, DC is electrical energy that travels in asingle direction within a circuit. DC current flows from onepole to another, hence it is said to have polarity (see Fig.1.4). The polarity indicates the direction of the flow of thecurrent and is signified by the + and – signs (see Fig.1.5).

Fig. 1.5 DC Voltage


Basic Numbering Systems

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Basic Number SystemsUse of digital technique started in 1940 military applications. Digital computerwas developed in 1960. Due to the development of semiconductor devicesdigital computer started becoming small in size. Digital technique is used inall areas of consumer electronic products, communication systems and industrialcontrols.

Digital technique has many advantages over analog system, such as

1) Reduce the cost 2) Improves the performance.

There are two basic types of electronic signals known as analog and digital.

Analog signals are of the most familiar type. It is AC or DC voltage that variescontinuously. It does not change abruptly or suddenly or in steps. Mostcommonly used analog signal is the sine wave as shown in fig 2.1. As youknow radio signals & audio tones are sinusoidal waves.

Electronic circuits which processes the analog signals are known as linearcircuits.

Digital signals are a series of pulses. These signals are voltages which variesfast between two fixed levels. As shown in fig 2.2.

Number Systems : Most of our thinking involves trying to find answer to twovalued questions. The answer may be true or false, it may be right or wrong,good or bad, etc. In electronic circuits also we say that a switch is open orclosed, as bulb is on or off. This two valued nature of thinking or logic is thebasic principle of Digital electronics. We can indicate anyone of the state byzero and the other by one. The electronic circuits designed for two-stateoperation are known as digital circuits. There digital circuits are able to senseonly one electrical quantity, the voltage. A digital circuit can distinguishbetween two distinct voltage levels and not intermediate value. Hence itbecomes necessary to evolve a number system which will have only two digits,instead of our normal decimal system having ten digits. This new system iscalled as binary system. A number system is nothing more than a code. Foreach distinct quantity, there is an assigned symbol. This section describes the

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Fig. 2.1 Analog Signal

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Fig. 2.2 Digital Signal

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binary number system and other new number system like octal and hexadeci-mal systems used. Before studying these new number systems, let us study fewbasic facts about the decimal number system.

Decimal number system : The base or radix of a number system refers tothe number of digits used. In decimal system 10 is used as base or radixbecause digits from 0 to 9 are used.

Each digit in the number has certain positions and that position determinesits weight. Positions, weights are from right to left, units, tens, hundreds,thousands

Eg. 1993. This can be represented as

1993 = Thousand Hundred Tens Units

= 1 x 1000 9 x 100 9 x 10 3 x 1

= 1 x 103 + 9 x 102 + 9 x 10 + 3 x 1

= 1000 + 900 + 90 + 3

= 1993

Note :1) The number of digits used in the system is equal to the radix or base.2) The largest digit is one less than the base i.e. 93) In the sum represented by a number each digit is multiplied by the base raised to the appropriate

power for digit position.

Binary number system : In the binary system the base is two and only twonumbers 0 and 1 are used. In binary system, only two signal levels are needed.

Reason of using binary number systems in the digital equipment is thatrepresenting decimal number by electronic circuit becomes complicated,costly and impractical for most applications. While the electronic circuitsrequired to represent binary systems is simple & inexpensive as an electroniccomponent or ckts with only 2 states is required for it is a binary system.

Group of four bits make a nibble. eg. 1111, 1100, 1101

A string of 8 bits make a byte. eg. 10001111, 11111111, 00011111

A byte is a basic unit of data in computers. Most computers process data instrings of 8 bits or 16, 24, 32 & so on.

As there are two number systems existing, there should be a procedure forconverting a number from one system into other. We now see the methods ofconversions.

[A] Binary to Decimal -

This conversion is accomplished in a very simple way. The procedure isas follows :

(1) Write the binary number

(2) Multiply each bit with the weight of each digit, (bit) 20, 21, 22, 23, etc1,2,4,8, 16... from right to left.

(3) Cancel the weights, where the bit is zero.

(4) Add the remaining digits to get a decimal number.


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eg. Convert 1010 into decimal

Step : 1 & 2 1010 = 1 x 23 + 0 x 22 + 1 x 21 + 0 x 20

= (1 x 8) + (0 x 4) + (1 x 2) + (0 x 1)

Step : 3 = 8 + 0 + 2 + 0

Step : 4 10

Therefore (1010)2 = (10)10

eg. (1111)2

Step : 1 & 2 1111 = 1 x 23 + 1 x 22 + 1 x 21 + 1 x 20

= (1 x 8) + (1 x 4) + (1 x 2) + (1 x 1)

Step : 3 = 8 + 4 + 2 + 1

Step : 4 = 15

Therefore (1111)2 = (15)10

The method for conversion of decimal fractions in binary form is same. Theweights of the numbers on the left hand side of decimal point increase from20, 21, 22... etc. If this continues from the decimal point to the right side, theweights are

2-1, 2-2, 2-3 ........etc.eg. Convert (0.0101) in decimal.

Step 1. 0.0101

2. 0.[0 x 2-1 + 1 x 2-2 + 0 x 2-3 + 1 x 2-4]

3. 0. [2-2 + 2-4]

4. 0. [1/4 + 1/16]

Ans. (0.0101)2 = (0.3125)10 = [0.3125]10

Naturally, for mixed numbers i.e. the numbers with integer as well as fraction,each part is solved separately and then joined.

The weight for a mixed number are :

..... 24 23 22 21 20 . 2-1 2-2 2-3

Binary Point

Decimal to Binary : This conversion is done in several ways. One way toconvert the given decimal number into binary is the reverse of the process seenabove. The number is expressed as a sum of powers of two, and then 1's and0's are written at appropriate positions.

eg. Convert 6 into binary

(6)10 = 8 4 2 1

= 0 + 4 + 2 + 0

= (0 1 1 0)2

Ans, (6)10 = (0 1 1 0)2


(27)10 = 16 8 4 2 1

= 16 + 8 + 0 + 2 + 1

= 1 1 0 1 1

Ans. (27)10 = (1 1 01 1)2


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The second method called as Double-Dabble method is easy and morefrequently used. The procedure is as follows.1 Divide the given number sucessively by 2.2 Write down the quotients directly below the given number.3 Write down the remainders on the right side.4 The remainders taken in reverse order from bottom to top, form the

number.eg.

(1) 13

Successive division Remainder2 132 6 1 L.S.B.2 3 02 1 1

0= 11012 1 M.S.B

(2) 24

Successive division Remainder

2 24

2 12 0 L.S.B

2 6 0

2 3 0

2 1 1

0 1 M.S.B

= 110002

The last quotient obtained by dividing 2 by 2 is 1. This 1 is not divisible by2. Hence the next quotient is 0 and 1 is transferred to remainders.


2 11

5 1

2 1

1 0

0 1

Ans. (11)10 = (1011)2

For the conversion of decimal fractions into binary fractions, the procedure isas follows :1 Multiply the fraction by 2.

2 The integer from the multiplication is kept aside.

3 The remaining fraction is again multiplied.

4 The integers obtained by this procedure form the binary number.

5 As the process is unending, it can be continued till the answer is sufficientlyaccurate.


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eg. Convert 0.65 into binary.

0.65 x 2 = 1.30 1

0.30 x 2 = 0.60 0

0.60 x 2 = 1.20 1

0.20 x 2 = 0.40 0

0.40 x 2 = 0.80 0

0.80 x 2 = 1.60 1

Ans. (0.65)10 = (101001)2

Note that, here the integers are taken in the same order as they are obtained.

eg. Convert 23.4 into binary.

First split 23.4 in two parts, 23.0 and 0.4Convert 23.0 using double-dabble method.Then convert 0.4 in binary.2 23

11 15 1 (23)10 = (10111)2

2 11 00 1

0.4 x 2 = 0.8 00.8 x 2 = 1.6 10.6 x 2 = 1.2 10.2 x 2 = 0.4 00.4 x 2 = 0.8 00.8 x 2 = 1.6 1(0.4)10 = (011001)2

Ans. (23.4)10 = (10111.011001)2

Following table shows the binary numbers upto 15

Decimal Binary

0 0

1 1

2 10

3 11

4 100

5 101

6 110

7 111

8 1000

9 1001

10 1010

11 1011

12 1100

13 1101

14 1110

15 1111


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Hexadecimal number system : Hexadecimal numbers are extensively usedin microprocessor work. To begin with they are much shorter than binarynumbers.

Hexadecimal means 16. The hexadecimal number system has a base or radixof 16. This means that it uses 16 digits to represent all numbers. The digitsare 0 through 9, and A through F as follows: 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, A,B, C, D, E and F. Hexadecimal numbers are strings of these digits like 8A5,4CF7 and EC58.

If used in a car, a hexadecimal odometer would count as follows. When thecar is new, the odometer shows all 0s :

0000 (zero)The next 9 miles produce readings of

0001 (one)0002 (two)0003 (three)0004 (four)0005 (five)0006 (six)0007 (seven)0008 (eight)0009 (nine)

The next 6 miles give000A (ten)000B (eleven)000C (twelve)000D (thirteen)000E (fourteen)000F (fifteen)

At this point the least significant wheel has run out of digits. Therefore, the nextmile forces a reset-and-carry to get

0010 (sixteen)

The next 15 miles produce these readings: 0011, 0012, 0013, 0014, 0015,0016, 0017, 0018, 0019, 001A, 001B, 001C, 001D, 001E and 001F. Onceagain, the least significant wheel has run out of digits. So, the next mile resultsin a reset-and-carry:

0020 (thirty-two)

Subsequent readings are 0021, 0022, 0023, 0024, 0025, 0026, 0027, 0028,0029, 002A, 002B, 002C, 002D, 002E and 002F.


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Table below shows the equivalences between hexadecimal, binary and decimal digits.Hexadecimal Binary Decimal

0 0000 01 0001 12 0010 23 0011 34 0100 45 0101 56 0110 67 0111 78 1000 89 1001 9A 1010 10B 1011 11C 1100 12D 1101 13E 1110 14F 1111 15

Lab Exercise 2.1: Conversion between Different Number Systems.

Objective: To be able to do the basic conversion of numbers between the differentnumbering systems.

Tasks:1. Convert (1001) into decimal2. Convert (56.75) into binary.3. Convert (101111.00111) into decimal4. Convert (1100) into Hexadecimal


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CMS COMPUTER INSTITUTE Introduction to PC

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Introduction to PC

GENERALA computer is a complex machine that incorporates diverse conceptualscientific, mathematical and engineering details.

It can be defined as a device that automatically performs arithmetic or logicaloperations on information input to it and provides an output according to the

performed set of instructions stored within it.

Hardware, Firmware and Software together make up acomputer system.

Hardware is a general term that describes all physicalcomponents used in the assembly of the computer. Itcovers all physical structure that uses binary state to move,or hold computer data.

Software is the intangible element that constitutes theinstructions on which the computer acts. This mostly consistsof programs meant to control and direct the performanceof the Computer. Hardware makes computing poweravailable. Software makes it usable.

Firmware are those programs that are permanentlywritten and stored in computer memory and are necessary for the control ofstartup, switch off and input/output procedure in computer these are introducedat the time of manufacture and cannot be normally altered.

Data is handled in the computer by electrical components such as transistors,integrated circuits, semi-conductors and wires, all of which can only indicatetwo states or conditions. Transistors are either conducting or non-conducting;magnetic materials are either magnetized or non-magnetised in one directionor in the opposite direction; pulse or voltage is present or not.

TERMINOLOGIES

All data is represented within the computer by the presence or absence of thesetwo states. The binary number system, which has only two digits, zero (0) andone (1) is, therefore, conveniently used to express the two possible states. One

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Fig. 3.1 Conceptual layers ina Computing environment

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binary digit is called BIT; the smallest unit of representing data in a computer.

All the familiar symbols which we use in writing are represented in the computerby a combination of bits. This combination forms a unique pattern thatrepresents each symbol. A set of such binary patterns include the letters (A -Z), decimal digits (0 - 9), and certain special characters such as punctuationmarks. A set containing all these characters is known as an alphanumeric

character set. The commonly used combination ofbit to form the alphanumeric character set is 8,because this gives us 256 unique permutationsthus allowing for letters, numbers, punctuationmarks, scientific symbols and other characters.One combination of 8 bits is known as a BYTE.

Computers also express information in the form ofwords. A computer's WORD is a group of bits, thelength of which varies from machine to machine,but it is normally pre-determined for each machine.The word may be as long as 64 bits or as shortas 4 bits. The word length determines the number

of bits that the CPU moves externally (between memory and devices) andinternally (between memory and processor) at a time.

FUNCTIONAL UNITSThe basic structure of a computer (refer fig. 3.2) can be divided into fourfundamental units.

(1) Central Processing Unit (2) Input devices

(3) Output devices (4) Storage section

The CPU combines two major parts.

a) Control Unit is responsible for regulating all activities which take placein the computer by reading and interpreting instructions and sending therelevant control signals to all other units which respond according to giveninstructions.

b) The ALU (Arithmetic Logic Unit) is responsible actually for processing thedata using arithmetic functions like (ADD, SUB) and logical functions like(AND, EX-OR etc.).

Some peripheral devices are only designed to input data and instructions intothe computer, like the keyboard, mouse and digitizer which are Input Devices.

There are some devices which can only be used for output of information, inthe form of reports, images and documents, for eg., the Visual Display Unit(VDU), printer and plotter which are Output Devices.

Fig. 3.2 Input-Output Processflow in a computer system



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The storage section can also be divided into 2 major parts

a) Internal or Primary Storage: consisting of RAM and ROM.

RAM, also called main memory, is volatile memory, retaining data only whenthe computer is powered ON. During the operation of the computer, systems(ie. pertaining to the operations of the machine) and application (ie. pertainingto user requirements) level instructions are stored in the RAM along with datato be processed. ROM, on the other hand is relatively permanent memory inwhich the system level instructions are held.

b) External or Secondary Storage: Floppy disks, Hard disks and Opticaldisks are essentially external or secondary storage media, storing datapermanently, operated by devices that are capable of both Input as well asOutput (hence referred to as I/O Devices). Devices that perform Input-Outputtasks are also commonly called External Devices.

SOFTWARE BASICSThere will be no work done in the computer systems without an instruction whichis the input given by the humans. This body of organised instructions is calledsoftware. Software is needed to instruct the hardware at various levels of itsfunctions which includes fundamental startup procedures and goes on to taskslike data processing, word processing and image processing.

Software is written by Programmers in one of the many Programming Languagesavailable. Refer fig 3.3. The important thing is to remember that the computeritself can understand only one language, appropriately called the MachineLanguage; a set of instruction codes written as string or bits. The earliestcomputer programmers had the difficult task of writing their programs in this

language. The inherent difficulty posed by machine languagelead to the development of easier ways to write programs.The first in this direction was the Assembler which translatedAssembly Language code to machine language code.

The assembly language is a direct translation of the machinelanguage code to easily understandable English type words,and after the program is written it is translated back by theassembler. Because of this, the cryptic element of the machinelanguage is present in the assembly language. High-levelLanguages, like C, BASIC, were developed to make thewriting of Application Software simpler. However it was notuntil the development and widespread use of C Languagethat system software was made in high level language. Thefourth generation languages are result-oriented and includedatabase query languages. These too have to be compiled

Fig. 3.3 Programming languages

PROGRAMMING LANGUAGES

1st GenerationMACHINE LANGUAGE

2nd GenerationASSEMBLY LANGUAGE

3rd GenerationHIGH LEVEL LANGUAGES

BASIC-COBOL-FORTRAN-PASCAL-C

4th GenerationDATABASE APPLICATION

DEVELOPMENT TOOLSalso called 4GLs

5th GenerationARTIFICIAL INTELLIGENCE

(AI)



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or interpreted. The fifth generation languages are intended to enable users tocommunicate with computers using natural language - the kind of languagehumans use to communicate with each other.

CLASSIFICATION OF SOFTWARESoftware can be classified into two distinct groups: System Software andApplication Software

System SoftwareThe software that instruct the computer to control and manage its internalfunctions, like initialising the start-up, controlling external devices, organisingthe memory during operations and many such other activities is called SystemSoftware. The most important system software is the Operating System (OS),which truly is the soul of the system. eg. Windows 98, Windows XP.

Application SoftwareThe software which performs a specific data processing job is called ApplicationSoftware. It consists of programs which carry out the specific processingrequired for user's application such as Word Processor, Spread Sheets, andFinancial Accounting or a computer-aided package. eg., MS Office, Tally, A-CAD etc.

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Introduction to Operating SystemCMS COMPUTER INSTITUTE

Introduction toOperating System

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Fig. 4.1 Abstract view of the components of a computer system.

GENERALComputer Hardware provides us with the means of processing and storinginformation. However, the 'bare' machine on its own is virtually useless. In orderto make the computer perform useful work for us, it is has to be 'driven' bymeans of programs - software - which specify the tasks to be done. Thecombination of hardware and software provide a total usable system.

An operating system is a program that acts as an intermediary between a userof a computer and the computer hardware. The purpose of an operatingsystem is to provide an environment in which a user can execute programs.The primary goal of an operating system is thus to make the computer systemconvenient to use. A secondary goal is to use the computer hardware in anefficient manner.

An operating system is an important part of almost every computer system.A computer system can be divided roughly into four components: the hardware,the operating system, the applications programs, and the users (Refer fig. 4.1).


compiler assembler text editor ... databasesystem

application programs

User User User ... User1 2 3 4

computerhard ware

OPERATINGSYSTEM

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The hardware - the central processing unit (CPU), the memory, and the input/output (I/O) devices - provides the basic computing resources. The applicationsprograms - such as compilers, database system, games, and business programs- define the ways in which these resources are used to solve the computingproblems of the users. There may be many different users (people, machines,other computers) trying to solve different problems. Accordingly, there may bemany different applications programs. The operating system controls andcoordinates the use of the hardware among the various applications programsfor the various users.

We can view an operating system as a resource allocator. A computer systemhas many resources (hardware and software) that may be required to solvea problem; CPU time, memory space, file storage space, I/O devices, andso on. The operating system acts as the manager of these resources andallocates them to specific programs and users as necessary for tasks. Sincethere may be many—possibly conflicting—requests for resources, the operatingsystem must decide which requests are allocated resources to operate thecomputer system efficiently and fairly.

A slightly different view of an operating system focuses on the need to controlthe various I/O devices and user programs. An operating system is a controlprogram. A control program controls the execution of user programs to preventerrors and improper use of the computer. It is especially concerned with theoperation and control of I/O devices.

Operating systems exist because they are a reasonable way to solve theproblem of creating a usable computing system. The fundamental goal ofcomputer systems is to execute user programs and to make solving userproblems easier.

Since bare hardware alone is not particularly easy to use, application programsare developed. These programs require certain common operations, such ascontrolling the I/O devices. The common functions of controlling and allocatingresources are then brought together into one piece of software i.e.: theoperating system.

A more common definition of the operating system is the one program runningat all times on the computer (usually called the kernel), with all the otherprograms, being application programs.

The primary goal of an operating system is convenience for the user. Operatingsystems exist because they are supposed to make it easier to compute withthem than without them. This view is particularly clear when you look atoperating systems for small personal computers.

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A secondary goal is efficient operation of the computer system. This goal isparticularly important for large, shared multiuser systems. These systems aretypically expensive, so it is desirable to make them as efficient as possible.

OS and computer architecture have had a great deal of influence on eachother. To facilitate the use of the hardware, operating systems were developed.As operating systems were designed and used, it became obvious that changesin the design of the hardware could simplify them.

FUNCTIONS OF OSAn OS is a program that performs four basic functions.

1. Communicate, or at least provide a method for other programs tocommunicate, with the hardware of the PC. It's upto the OS to access thehard drives, respond to the keyboard, and output data to the monitor.

2. OS must create a user interface - a visual representation of the computeron the monitor that makes sense to the people using the computer inputdevices, such as mice and keyboards, to enable users to manipulate theuser interface and thereby make changes to the computer.

3. OS, via the user interface, must enable users to determine the availableinstalled programs and run, use, and shut down the program of theirchoice.

4. OS should enable users to add, move, and delete the installed programsand data.

OPERATING SYSTEMS AND BIOSThe PC is used for a number of purposes. The hardware configuration variesto some extent to suit a specific application. Still the hardware organisationand principle of operation of the PC is common to all applications. Only thesoftware differs from one application to another. In most of the applications,the system software used is the same. It is the application software which differs.The hardware in a PC does not know the software. The BIOS is the interfacebetween hardware and software. It is also a software but is called firmwaredue to its integration with hardware. Without BIOS, the PC is a dead machine.

On PC's, the BIOS contains all the code required to control the keyboard,display screen, disk drivers, serial communications and a number ofmiscellaneous functions.

The BIOS is typically placed in a ROM chip that comes with the computer itis often called a ROM BIOS. This ensures that the BIOS will always be availableand will not be damaged by disk failures. It also makes it possible for acomputer to boot itself. It is the BIOS which controls the hardware accordingto the requirements of the OS.

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Many modern PCs have a flash BIOS, which means that the BIOShas been recorded on a flash memory chip, which can be updatedif necessary.

CLASSIFICATIONAn operating system is conceptually broken into two components:-A shell and a kernel. As the name implies the shell is an outerwrapper to the kernel which in turn talks directly to the hardware.(Refer fig. 4.2).In some operating systems the shell and the kernel are completelyseparate entities, allowing you to run varying combinations of shellkernel (eg Unix), in others their separation is only conceptual (eg.

Windows).

Kernel design ideologies include monolithic kernel, microkernel and exokernel.Among commercial systems, Unix and Windows use the monolithic approach.The microkernel approach is more popular among modern systems such asQNX, BeOS, Windows NT etc. Many embedded systems use ad-hoc exokernels.

TYPES OF OPERATING SYSTEMSWithin the broad family of operating systems, there are generally the followingtypes as mentioned below, categorized based on the types of computers theycontrol and the sort of applications they support. The broad categories are:

• Single-user, single task - As the name implies, this operating systemis designed to manage the computer so that one user can effectively doone thing at a time. DOS is a good example of a single-user, single-taskoperating system.

• Single-user, multi-tasking - This is the type of operating system mostpeople use on their desktop and laptop computers today. Windows 98 andthe MacOS are both examples of an operating system that will let a singleuser have several programs in operation at the same time. For eg. it'sentirely possible for a Windows user to be writing a note in a wordprocessor while downloading a file from the Internet while printing the textof an e-mail message.

• Multi-user - A multi-user operating system allows many different users totake advantage of the computer's resources simultaneously. The operatingsystem must make sure that the requirements of the various users arebalanced, and that each of the programs they are using has sufficient andseparate resources so that a problem with one user doesn't affect the entirecommunity of users. Unix, Windows 2000, Linux and mainframe operatingsystems, are examples of multi-user operating systems.


Applications

Shell

Kernel

Hardware

Fig. 4.2 Relationshipbetween the differentcomponents of OS

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Disk Operating System & CommandsCMS COMPUTER INSTITUTECMS COMPUTER

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5PC ENGINEERING

BRIEF HISTORY OF DOSThe history of DOS is intimately associated with that of the IBM PersonalComputer (and 'compatible' computers). Towards the end of the 1980s, anumber of personal computers had appeared on the market, based on 8-bitmicroprocessor chips such as the Intel 8080. IBM made the decision to enterthis market and wisely opted to base their computer on a 16-bit processor,the Intel 8088. IBM wanted to bring the PC to the market as quickly as possibleand realised that it did not have time to develop its own operating system.At that time, the operating system CP/M from Digital Research dominated themarket.

CP/M was written by Gary Kildall of Digital Research with whom IBM hadnegotiations but the negotiations did not result in an agreement. IBM then hadgiven the contract to write the new OS to Microsoft.

In 1979, a small company called Seattle Computer Products, whichmanufactured memory boards, decided to write its own operating software totest some of its Intel based products.

This software called as QDOS (Quick and Dirty Operating System) was madeby Tim Patterson of Seattle Computer Products, for their prototype Intel 8086based computer.

QDOS was based on Gary Kildall's CP/M. Patterson had bought a CP/Mmanual and used it as the basic to write his OS in 6 weeks, QDOS was differentenough from CP/M to be considered legal.

Microsoft bought the rights to QDOS for a nominal amount keeping the IBMdeal a secret from Seattle Computer Products. Microsoft made slight changesto QDOS and then presented "Microsoft Disk Operating System" or MS-DOSto IBM. Bill Gates, the president of Microsoft then talked IBM into lettingMicrosoft retain the rights, to market MS DOS separate from the IBM PCproject.

The IBM PC was announced in August 1981, with version 1.0 of MS-DOS,

Disk Operating System& Commands

22

Disk Operating System & CommandsCMS COMPUTER INSTITUTE

referred to by IBM as simply DOS and later as PC-DOS.

After IBM selected MS-DOS, more than 50 other hardware manufacturers alsoused it. This resulted in Bill Gates making a fortune from the licensing of MS-DOS which has now been updated several times.

MICROSOFT DOSMicrosoft designed DOS to run on an 8086 processor. Microsoft never trulyupgraded DOS to take advantage of the more advanced Intel processors'protected mode. DOS remains as it began, a single-tasking OS.

The interface of DOS was command line, meaning that there was no mouse,no menus, or any graphical components. Text commands were entered fromthe keyboard and the computer's response appeared as text on the monitor.DOS controlled some aspects of the computer hardware particularly diskaccess and basic CPU operations, but it was still common to configure thevideo display, sound card, printer etc. for each application that would usethem. DOS uses the files and directories in the following ways.

DOS manifests each program and piece of data as an individual file. Eachfile has a name, which is stored with the file on the drive. Names are brokendown into two parts: the filename and the extension. The file name can be nolonger than eight characters. The extension, which is optional, can be up tothree characters long. No spaces or other illegal characters (/ \ [ ] | < > += ; , * ?) can be used in the filename or extension. The file name and extensionare separated by a period, or "dot." This naming system is known as the "eightdot three" (written as "8.3") system.

Here are some examples of acceptable DOS filenames:WORD.EXESYSTEM.INIAJAY.DOCDRIVER3.SYSDILIPTRISHAL.H

Here are some unacceptable DOS filenames:AJAY.EXECWAYTOOLONG.FDILIP>CHAR.BAT.NO

The extension tells the computer the type or function of the file. Program filestake the extension EXE (for "executable") or COM (for "command"). Anything that

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is not a program is some form of data to support a program. Differentprograms use different types of data files. The extension is used to indicatewhich program uses that particular data file. For eg. Microsoft Word for DOS(yes, there was a Microsoft Word for DOS) uses files with the extension DOC.Changing the extension of a data file does not affect its contents, but withoutthe proper extension, it is difficult to know which program uses it.

Drives and DirectoriesDOS assigns a drive letter to each hard drive partition and to each floppy orother disk drive. The first floppy drive is called A:, and the second, if installed,is called B:, DOS cannot support more than two floppy drives, because itsupports the original IBM PC, which was designed for only two drives. Harddrives start with the letter C: and can continue to Z: if necessary.

DOS uses a hierarchical directory tree to organize the contents of these drives.All files are put into groups called directories.

DOS STRUCTURE: THREE MAIN FILESThe DOS operating system is composed of three main files, accompanied byroughly 80 support files. The three main files are IO.SYS, MSDOS.SYS andCOMMAND.COM. These files must be on the C: drive or the computer willnot boot. IO.SYS handles talking to the BIOS and hardware; MSDOS.SYS isthe primary DOS code, often called the kernel; and COMMAND.COM actuallyinterprets commands typed into the computer and passes that information toMSDOS.SYS. COMMAND.COM is also called the Shell or command interpreter.The command interpreter stores a number of commands that you may enterto get work done.

DOS COMMANDSDOS has two types of commands.

(1) Internal Commands (2) External Commands

INTERNAL DOS COMMANDS :These commands reside in computers memory and can be executedimmediately. When the DOS prompt (:>) is displayed on the screen the usercan use any of these internal DOS commands. Once the DOS is loaded intothe computer's memory internal DOS commands is always available to theuser.The internal command routines are loaded onto the memory as a part of theboot-sequence, while the external commands routines reside as files in the disk.Commands like TIME, DATE and CLS are internal, so we didn't have to worry aboutwhere they are present in the disk. In this unit some of the commands we will learnare external commands, and therefore we must ensure that they are present in the

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.

disk, drive and path that we are using. The essential DOS commands are thosewithout the knowledge of which even the basic operations of the PC will not bepossible. They fall under three categories:(1) Managing directories (2) Managing files (3) Disk management

Some INTERNAL DOS commands are as follows :

DIRto view the contents of a directory

Syntax dir {drive:}{path}{filename}{.ext}{/P}{/W}{/A{{:}attribute}}{/O{{:}sortorder}}{/S}{/B}{/L}

If no parameters are given then the contents of the current directory is listed incontinuous scroll.

C:\> dirA valid drive designator as drive will list the active directory of the specified drive:

C:\> dir a:Similarly a pathname will list the directory specified:

C:\> dir \windows\tempA filename, an extension, with or without wild card characters can be used tonarrow down the display list.

C:\> dir a*.*C:\> dir a*.txtC:\> dir .exe

The following are the DIR command switches:/p pauses between each screen-full display./w displays the listing in wide format./a displays only the names of directories and files with the specified attribute.

When this not used, DIR displays all files except those with hidden or systemattribute. If used without any attribute all files including the hidden andsystem files are displayed. The following list describes the values that areused for attribute. The colon (:) is optional. Any combination of values canbe used; do not separate them with spaces.h hidden files -h not hidden filess system files -s not system filesd directories only -d files onlya changed since last backup -a unchanged since last backupr read-only files -r not read-only files

/o controls the order in which DIR sorts and displays directory names andfilenames. If omitted, DIR displays in the order of occurrence in the directory.If used without the sortorder, DIR displays first sorted directory names and

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then the sorted filenames. The colon (:) is optional. The following listdescribes the values used for sortorder. Any combination of values can beused; do not separate these with spaces.n by name (A to Z) -n by name (Z to A)e by extension (A to Z) -e by extension (Z to A)d by date-time (earliest first) -d by date-time (latest first)s by size (smallest to largest) -a by size (largest to smallest)g directories first -g files first

/s lists all occurrence of filename in specified directory and its subdirectories./b lists, one per line, each directory name or filename, (including the exten-

sion). Suppresses the heading and the summary information. The /B switchoverrides the /W switch.

/l displays unsorted directory contents in lowercase. Does not, however,convert extended characters into lower case.

CDto change from one directory to another

Syntax cd {drive:}{path}{..}

The disk on each drive of the system has a current directory. If there are two floppydisks and a hard disk, there are three current directories. If a disk has nosubdirectories then the root directory is always the current directory. If the disk hassubdirectories the CD command is used to move from one directory to another.If drive is other than the current drive, CD changes the current directory in that driveto root directory or to the path directory specified as parameter, but does notmove to that directory.

A:\> cd c:A:\>cd c:\word

Hence it should be clear that to actually move to another directory, it must be inthe path on the current drive. To return to the root directory from any position inthe tree, only the backslash parameter needs to be issued. Remember, the firstbackslash in the path refers to the root directory.

C:\WORD> cd \To return to the parent directory from the current child directory, use double dot(..) parameter. This will also return to root directory if the current directory is itschild. Similarly, to move from parent directory to child directory, the backslashneed not be specified, infact this allows omitting the full path designator:

C:\WORD\LOOKUP> cd..C:\WORD> cd..C:\> cd wordC:\WORD> cd lookup

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To move directly from any directory to another directory, irrespective of itsposition in the tree, the full path needs to be specified:

MDto make a new directory

Syntax md {drive:}{..}{path}{name}

To create a new subdirectory from the current directory the required parameteris the name:

C:\> md dataC:\PROGRAM> md data

To make new subdirectory in any directory, other than the current directory, thepath must be provided. If the subdirectory is to be created in another drive thedrive must be specified:

C:\> md \word\tempC:\> md ..\word\tempC:\WORD> md \tempC:\> md a:\temp

The name of the new directory must be unique in the directory it is being created,however more than one directory with the same name can exist in different paths.

RDto remove or delete a directory

Syntax rd {drive:}{..}{path}{name}

To delete a directory which is the subdirectory of the current directory the requiredparameter is the name:

C:\> rd dataC:\PROGRAM> rd data

To delete directory which is not a subdirectory of the current directory, the pathmust be provided. If the subdirectory in another drive is to be deleted the drivemust be specified:

C:\> rd \word\tempC:\> rd ..\word\tempC:\WORD> rd \tempC:\> rd a:\temp

The most important aspect of the RD command is that the directory to be removedmust be empty which means no files or directories must be present in it. The RD

command will not act on the current directory. If after all the files and directorieshave been removed and the target directory is not active, and yet RD does not

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delete the directory then there would be some hidden or read-only file stillpresent in it, which must be first removed.

TYPEdisplays the contents of a text file

Syntax type {drive:}{path}{filename}

C:\> type autoexec.bat

COPYcopies one or more files to another location

Syntax copy {CON}{/A|/B}{{source {/A|/B}}{+source {/A|/B}}{+ ...}}

{destination {/A|/B}}{/V}{printerport}

Specify the location and the name of the file or set of files to copy the as sourceparameter. The source can consist of drive designator and colon, a directoryname, a filename, or combination. The destination correspondingly specifiesthe location and name of the file or set of files to which to copy. The destinationcan consist of a drive designator and a colon, a directory name, a filename orcombination.

A:\>copy thisfile.doc c:thatfile.txtA:\>copy thisfile.doc c:A:\>copy thisfile.doc c:\word\thatfile.txtA:\>copy *.* c:A:\>copy c:*.docA:\>copy c:\thisfile.doc

c:\word\thatfile.txtA:\>copy thisfile.txt c:thatfile.txt

To copy a file directly from the keyboard or to create a fileC:\>copy con runprog

To copy a disk file onto a printer, the printer port name has to be provided,normally your printer would be connected to the port LPT1. Using CON and printerport name you can copy a file directly from the keyboard to the printer:

C:\> copy thatfile.txt lpt1A:\> copy con lpt1

RENchanges the name of a file or files

Syntax ren {drive:}{path}{ filename}{newname}

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If the files to rename are not in the current directory, the drive and path will needto be specified. The ren command changes the name of file(s) in place, andtherefore renaming across directories is not possible. The filename is the existingname of the file(s) and newname is the changed name. Wild card characters canbe used:

C:\> ren thisfile.txt thatfile.txtC:\> ren a:thisfile.txt thatfile.txtC:\> ren *.txt *.bxtC:\> rename thisfile.txt thatfile.txt

DELdeletes specified a file or a group of files

Syntax del {drive:}{path}{ filename}{/p}

If the files to del are not in the current directory, the drive and path will need tobe specified. The filename is the name of the file(s). Wild card characters can beused:

C:\> del thisfile.txtC:\> del a:thisfile.txtC:\> del *.txtC:\> del a*.*C:\> del \word\lookup\*.txtC:\> erase thisfile.txt

Use the /p to make del issue a prompt for confirmation before deleting thespecified file(s).

CLSClears the screen

Syntax clsThe CLS command is invoked without parameters. It will erase all characters onthe screen and display the operating system prompt, if any on the first line on thedisplay.

EXTERNAL DOS COMMANDSExternal DOS commands are executable programs with .COM or .EXE filename extension and to use any of the external DOS commands, the commandmust be available on the floppy disk or the hard disk drive.

Some External DOS Commands

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EDIT

Starts a full-screen text editor.

Syntax edit drive:\path\file /d

EDIT is a menu-driven text editor. If you invoke EDIT without parameters theeditor appears without a default open file. Alternatively, you may specify a filefor EDIT to open when it loads.

Eg.edit MY-TEXT.FIL

starts the editor with MY-TEXT.FIL as the default. If the file doesn't already exist,the editor creates it.

XCOPYcopies files and directories, including sub-directories.

Syntax xcopy source{destination}{/A|/M}{/D:date}{/P}{/S{/E}}{/V}{/W}

The source specifies the location and the names of the files you want to copy, itmust include either a drive or a path. The destination specifies the target locationof the files you want to copy. Destination can include a drive designator andcolon, a directory name, or a combination:

A:\> a: b:C:\> c:\program\database a:C:\> c: \backup

If the destination directory does not exist XCOPY prompt for creation of a newdirectory in the specified path. If the prompt is to be avoided a backslash mustbe added at the end of the destination directory; XCOPY will go ahead and createa new directory.

A:\> xcopy a: c:\word\tempA:\> xcopy a: c:\word\temp\

If no destination is given then XCOPY copies files from the source to the current driveand current directory, provided of course the source is not the current directory.

A:\> xcopy c:\word\tempC:\PROGRAM\DATABASE> xcopy c:\word\temp

XCOPY supports the following switches, that enhance the use of the command:/a copies those source files that have their archive file attributes set. This switch

does not modify the archive file attribute of the source file./m copies source files that have their archive file attributes set. Unlike /A, the

/M switch turns off archive file attributes in the files specified in source.

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/p prompts for user confirmation before creating each destination file./s copies directories and sub-directories, but ignores if they are empty. If this

switch is omitted, XCOPY works within a single directory./e copies all sub-directories even if they are empty. This switch must be used

along with the /S switch./v verifies each file as it gets written to the destination file to make sure that

the destination file is identical to the source files./w displays the following message and waits for user response before starting

to copy files:Press any key to begin copying file(s)

DELTREEThis command removes a directory, file and subdirectories.

Syntax deltree /switch drive: \path

Use the DELTREE command to quickly remove an unwanted directory plus allfiles on it, and all subdirectories nested below it, using a single command.

deltree C: \XYZ

prompts for confirmation and, if you enter Y, deletes the \XYZ directory andall files in this directory.

ATTRIBdisplays or changes file attributesSyntax attrib {+R|-R}{+H|-H}{+A|-A}{+S|-S}

{{drive:}{path}{filename}}{/S}

To display the file attributes, only the file location parameters are used, whereasto set or remove the file attribute switches are to be specified before file locationparameters.

C:\> attrib a:onefile.docC:\> attrib a:*.*C:\> attrib

The following are the ATTRIB command switches+resets the read-only file attribute.-r clears the read-only file attribute.+a sets the archive file attribute.-a clears the archive file attribute.+h sets the hidden file attribute.-h clears the hidden file attribute.+s sets the system file attribute.-s clears the system file attribute.

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/s processes files in the current directory and all of it’ssubdirectories.

Wildcard characters can be used with the filename parameter to display orchange the attributes of a group of files. If a file has a system of hiddenattribute set, the attribute must first be cleared before the change can bemade.

FORMATprepares the disk to accept DOS files

Syntax format {drive:}{/V{:label}{/Q}{/U}{/F:size}{/B}{/S}{/T:tracks}{/N:sectors}{/L}{/4}{/8}

The FORMAT command creates a new root directory and file allocation table for thedisk. It can also check for bad areas on the disk, and it deletes all data on the disk.In order that DOS is able to use a new disk, it must first be FORMATTED. The driveparameter specifies the drive containing the disk to be formatted.

C:\> format a:

If the following switches are not mentioned, FORMAT uses the drive type todetermine the default format for the disk.

/v:labelspecifies the volume label. A volume label identifies the disk and can beof maximum 11 characters. If you omit the switch, or use it withoutspecifying a label. MS-DOS prompts you for the volume label afterformatting is complete. If you FORMAT more than one disk using only oneFORMAT command, all of the disks will be given the same volume label. The/V switch is not compatible with the /8 switch.

/q deletes the file allocation table and the root directory of a previouslyformatted disk, but does not scan the disk for bad areas. You should usethis switch to format only disks which have been previously formatted andwhich you know are in good condition.

/u specifies an unconditional format operation for a floppy disk or a harddisk. Unconditional formatting destroys all the existing data on a disk andprevents it from later unformatting the disk. You should use /U if you havereceived read or write errors during use of the disk.

/s copies the operating system files io.sys, ms-dos.sys and command.comfrom your system’s startup drive to the newly formatted disk. If formatcannot find the operating system files, it prompts you to insert a system disk.

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REDIRECTIONSMS-DOS receives input from your keyboard and sends output to your screen.Sometimes it is important to redirect the input or the output to a file or a printer.For example, you might want to redirect a directory listing from the screen toa file. The greater-than (>) sign sends the output to a file or a device, suchas a printer. The less-than (<) sign takes the input needed for a command froma file rather than from the keyboard. The double greater-than (>>) sign addsthe output from a command at the end of a file without deleting the informationalready in the file. The pipe (|) is used to redirect output from one commandto another command. For example:

C:\> dir > dirlist.txtC:\> dir > lpt1C:\> sort < list.txtC:\> dir >> dirlist.txt

Another command which uses the redirection symbol is given below.

MOREdisplays one screen of output at a time.

Syntax more < {drive:}{path}{filename} or

{command} | more

The more command reads standard input from a pipe or redirected file anddisplays one screen of information. This command is commonly used to viewlong files. When using a redirection character (<), you must specify a filenameas the source. When using the pipe (|), you can use such commands as dir,sort and type.

FILES OF DOSDOS provides two special text files for adding control to new hardware: devicedrivers via CONFIG.SYS and AUTOEXEC.BAT

Device DriversThe most common way to add BIOS is through special files called device driver.A device driver is little more than a file containing all the programmingnecessary to talk to a new device. Device drivers usually come from the samecompany that makes the hardware. If you buy a sound card or network card,it will come with a diskette or CD-ROM containing the necessary file(s). MostDOS device driver files use the extension SYS. Some eg., of DOS device driversare DRIVER.SYS, 3C509.SYS, and CLTV3.SYS.

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CONFIG.SYSWhen the computer is turned on, DOS checks for a CONFIG.SYS file andadjusts your computer's configuration according to commands contained inthat file. The CONFIG.SYS file is always found on the main directory of theDOS boot disk. If you have a hard disk system, it is found on drive C, althoughyou can boot from a floppy disk even when using a computer equipped witha hard disk. DOS is almost always on drive A when using a floppy disk-basedmicrocomputer.

Device drivers load through a special file called CONFIG.SYS, a text file thatmust be in the root directory of the C: drive.

The most common way to add device drivers in DOS is first to copy the devicedriver onto the C: drive from the floppy drive or CD-ROM (either manuallyusing the COPY command, or automatically by running an installation programthat does the copying for you). Either way, the result is a device driver on theC: drive, usually in its own directory. Once the device driver is copies to theC: drive a line is added to the CONFIG.SYS file. This line starts with DEVICE=or DEVICE-HIGH=, followed by the path/name of the device driver.

Config.sys is used for much purposes than simply loading device drivers. DOSuses a large number of configuration commands to set up such as definingthe buffer space during disk I/O process, the size of stack memory, to definecertain space for monitoring frequently accessible files and to define any othershell other than the "command.com".

Batch FileDOS lets you create and store a series of DOS commands that are acted upon(or "executed") automatically one line at a time in the order entered. The filecontaining the series of DOS commands is called a batch file. These files musthave the extension .BAT and contain legitimate DOS commands on each line.

If the batch file is given the special filename AUTOEXEC.BAT, it is executedautomatically when you first start your computer. If the batch filename is givenanother name, like CMS.BAT, you must type CMS and press Enter for thecommands in the batch file to run.

AUTOEXEC.BATThis file automatically runs (or executes) the command lines included withinthe file when your system is turned on. Each command encountered in this fileis run as if you typed it directly from your keyboard. Like CONFIG.SYS, DOS"looks" for the AUTOEXEC.BAT file during the boot process.

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Fig. 5.1 Directory Structureto be created

LAB EXERCISE 5.1 : Basic DOS Commands

Objective: To be familiar with the different Internal and External DOSCommands.Tasks:1. Create the directory structure as shown in the fig. 5.1.2. Check the data and time of your machine.3. What is version of DOS that you are using.4. Create a file "Intro95" into "W95" directory.5. Create a file "biodata" into "network" directory.6. View the contents of "Intro95" file.7. Create a file "TCP/IP" into "network" directory.8. Copy contents of "W95" to "PCE".9. Copy all files with extension DLL from any other directory to "DBA".10. Rename file "biodata" to "resume".11. View all the files including subdirectories in "student" (widthwise and

pagewise).12. Check all hidden files at 'C' prompt.13. Delete the directory "nettech".14. Delete all the files starting with 'S' from directory "network".15. Install doskey on your machine.16. Copy contents of directory "student" to "student1" including all its

subdirectories and empty directories.17. Check attributes of all the files in root.18. Hide the file "intro95". Can you reset the same attribute?19. Format the given drive such a way that the previous data cannot be

recovered (format a: /u).20. How you will format the given floppy quickly? (format a: /q)21. What is /q and /s option in format commands.22. Make the given floppy bootable using sys command. (sys a:)20. Delete the directory "student 1" with all its subdirectories.21. Change the contents of resume file using MS-DOS editor.22. a. Create a file "X.bat" with the given contents using DOS Editor.

datedir/ppauseclsecho "your system is affected by virus, please reboot the machine".

b. Executee C:\>x.bat on the machine.Write the conclusion.

35

Microsoft Windows VistaCMS COMPUTER INSTITUTECMS COMPUTER

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Microsoft Windows Vista

Windows Vista Client

Operating systems control the functions performed by a computer. For eg, theoperating system on your computer controls the input from the keyboard andmouse to your computer, the opening and closing of programs, the transferof information to a printer, the organization of the files on your computer, andthe screen display. To function, every computer must have an operating system.Windows Vista is an operating system. It was released by the MicrosoftCorporation in late 2006.

Windows Vista comes in several versions: Home Basic, Home Premium,Business, Ultimate, and Enterprise. The features available to you depend onthe version of Windows Vista you have.

Windows Vista Enterprise is for large global organizations and is only availableto organizations with desktops covered by Software Assurance agreements ororganizations with a Microsoft Enterprise Agreement that includes the Windowsdesktop component.

Windows Vista Home Basic is the entry-level edition. Geared toward homecomputer users, Home Basic has features that allow you to search yourcomputer, search the Web, browse the Internet, view photos, send and retrievee-mail, and set parental controls. Windows Defender and Windows Firewallare included with Windows Vista Home Basic. Windows Defender helps protectyour computer from spyware. Spyware is malicious software you install on yourcomputer inadvertently or is put on your computer without your consent.Windows Firewall helps protect your computer from malicious software andunauthorized access to your computer.

Windows Vista Home Premium has most of the features found in Windows VistaHome Basic plus additional features such as Aero, Windows Media Center,Windows Meeting Space, Windows Mobility Center, Windows SideShow, andTablet PC support. Windows Aero features translucent windows and smoothanimations, including the capability to do three-dimensional flips throughopen windows. It also provides a thumbnail preview of the contents of open

36

Microsoft Windows VistaCMS COMPUTER INSTITUTE

windows when you pause your mouse pointer over the window's identifier onthe taskbar or Alt-Tab through windows. With Windows Media Center, you canrecord and watch TV shows, listen to Internet and FM radio, view home movies,create slide shows, and burn CDs or DVDs. You can use Windows MeetingSpace to set up meetings in which you can share documents, programs, oryour desktop with others. Windows Mobility Center provides a convenientlocation for you to adjust the settings for your mobile PC. With WindowsSideShow, you can send information from your computer to other devices suchas mobile phones, hand-held computers, and TVs. A tablet PC is a mobilecomputer that you can interact with by writing on the screen or by using yourfinger or a pen. You can use Windows Vista Premium with a tablet PC.

Windows Vista Business is designed for small businesses. It is simple to useand has mechanisms that protect your information from unauthorized viewing.

Windows Ultimate includes all the features of Windows Vista Home Premiumand Windows Vista Business and has extra features such as DreamScene,Language Packs, and BitLocker Drive Encryption. With DreamScene, you canuse full-motion video as your wallpaper. Language packs allow you to installmultiple languages on a single PC. BitLocker Drive Encryption encrypts yourdata to protect it from unauthorized viewing.

Windows Vista Feature Comparison

Fe a tur es Bas i c H om e Business U l t ima teP r em iu m

Windows Defender X X X X

Windows Firewall X X X X

Instant Search X X X X

Network and Sharing Center X X X X

Internet Explorer 7 X X X X

Parental Controls X X

Windows Aero X X X

Mobility Center X X X

Tablet PC Support X X X

Windows Meeting Space X X X

Windows Sideshow X X X

Windows Media Center X X

Windows Complete Backup and Restore X X

Windows Fax and Scan X X

Scheduled Backup X X X

Remote Desktop Connection X X

Window BitLocker Drive Encryption X

Windows DVD Maker X X

Windows Movie Maker in High Definition X X

If you do not have Windows Vista or if the version of Windows Vista you have does not have the features

you need, you can upgrade your operating system.

37


What is a desktop?

If you are using Windows Vista,after you start your computer thefirst thing you see is the desktop.The desktop is your work area.

The following table explains thevarious features of the WindowsVista desktop.

Fig. 6.1 Windows Desktop


Feature Explanation

Taskbar By default, the taskbar is located on the bottom edge of the

desktop. You can click the taskbar and drag it to other locations.

The Start button, active program buttons, icons for quick accessto programs, and the notification area are located on the

taskbar.

Recycle Bin When you delete an object, Windows Vista sends it to the

Recycle Bin. You can restore objects from the Recycle Bin or you

can permanently delete them.

Shortcut icon Icons with an arrow in the lower-left corner are shortcut icons.

Click the icon for quick access to the object it represents

(program, document, printer, and so on).

Program, Program, folder, and document icons do not have an arrow in

the lower-left corner. These icons represent the actual objectsand provide direct access to the objects. Be careful: When you

delete a program, folder, or document icon, you are deleting

the actual program, folder, or document.

Sidebar The default placement for the Windows Vista sidebar is along

the right side of your desktop. You can use the sidebar to display

gadgets. Gadgets are small programs with which you candisplay a clock, post notes, track stocks, or perform other

miscellaneous tasks.

folder, anddocumenticons

38


Fig. 6.2 taskbar properties

What is ataskbar?

The taskbar is a longbar that by defaultruns along thebottom of yourdesktop. The Startbutton, QuickLaunch toolbar,


active program buttons, and the notification area are located on the taskbar.

1 Start

2 Quick Launch Toolbar

3 Active Program Buttons

4 Notification Area

You click the Start button to display the Start menu. You use the Start menuto open programs and to perform other functions such as searching for files.

On the taskbar, right next to the Start button is the Quick Launch toolbar. Usingthe Quick Launch toolbar, you can open a program or file simply by clickingits icon. To add an icon to the Quick Launch toolbar:

1. Locate the program you want to add.

2. Right-click. A context menu appears.

3. Click Add to Quick Launch. Vista adds the program to the Quick Launchtoolbar.

Fig. 6.3 Quick Launch


1 Show Desktop

2 Switch Between Windows

Two icons appear on the Quick Launch toolbar by default: the Show Desktopicon and the Switch between Windows icon. You can display the desktop byclicking the Show Desktop icon. You can use the Switch between Windows iconto display all open windows in 3D flip if your version of windows has Aero or

you can use theSwitch betweenWindows icon to tabthrough openwindows if yourversion of Vista doesnot have Aero.Fig. 6.4 Active Program Button


39


When using Vista, each program,document, or other type of fileopens in its own window. You canhave multiple programs,documents, and files open at a

Fig. 6.5 Notification Area


given time. A button for each open program, file, or document window displayson the taskbar. You can quickly move from one open file to another open fileby clicking the files button. If you have a large number of files open, Vista maygroup all files of a given type together. For example, if you have severalMicrosoft Word documents open, Vista may group them together. When youclick the button for Microsoft Word, Vista displays a menu of open Word files.You can click the document you want to open.

The notification area is located on the right side of the task bar. It displaysseveral icons and the current time. The icons that display depend on the wayin which your computer is configured. You can move your mouse pointer over

an icon to see the currentsettings for the option the iconrepresents. In many cases, youcan click the icon to changethe settings. For example, theVolume icon is located in thenotification area. When youpause your over the Volumeicon the volume setting for thespeakers on your computerappears. You can click the iconto adjust the volume.

When I finish workingwith my computer, whatshould I do?

When you finish working withyour computer, you should putyour computer in sleep mode:

Fig. 6.6 Put your computer in Sleep Mode


1. Click the Start button. TheStart menu appears.

2. Click the Power button.Vista puts your computerin the sleep mode.

40


When you click the Power button, Vista saves all of your work, turns off thedisplay screen, and puts your computer in sleep mode. To indicate that yourcomputer is in sleep mode, some of the lights on your computer may blinkand/or change color.

What is sleep mode?

In sleep mode, your computer consumes very little electricity. When you needto use your computer again, you can press your computer's power-on switchto resume work quickly. Instead of shutting your computer down when you arenot using your computer, you should put your computer in sleep mode.

I am using a laptop. Won't putting my computer in sleep modedrain my computer's battery?

A sleeping computer uses very little energy. Microsoft, the maker of WindowsVista, recommends that you put your computer, whether a desktop or a laptop,in sleep mode when you are not using it. A sleeping computer should not drainyour computer's battery. However, if your power becomes dangerously low,Vista saves your work to your hard drive and then shuts your computer down.

How do I wake up my computer?

To wake up your computer, press your computer's power-on switch.

Do I ever need to shut down my computer?

Generally, when you are not using your computer, you should put yourcomputer in sleep mode. However, if you are making changes to yourcomputer hardware, such as installing memory or adding a hard drive, youshould shut your computer down. You may also need to shut your computerdown when you add hardware to your system, such as a new printer.

How do I shut down my computer?

Fig. 6.7 Shut down your Computer


1. Click the Start button. TheStart menu appears.

2. Click the arrow in thelower-right corner of thestart menu. A menuappears.

3. Click Shut Down. Yourcomputer shuts down.

When you need to restart yourcomputer, press yourcomputer's power-on switch.

41


What is a program?

You use programs, also referred to assoftware, to perform tasks when using acomputer. For example, if you want to useyour computer to write a letter, you can usea word-processing program such as MicrosoftWord. If you want to keep accounting records,you can use an accounting program such asQuickBooks.

Program?

To start a program:

1. Click the Start button, located in the lower-left corner of your screen. A menu showingthe programs you use most frequentlyappears on the left, and commonlyperformed tasks appear on the right.

2. Click the program you want to open. Vistastarts the program.

I do not see the program I want toopen. What should I do?Fig. 6.8 Menu showing the program


After you click the Start button, a search box appears just aboveit. You can use the search box to locate programs or anything elsethat is located on your computer, including documents that containthe word you type. Type the name of the program, e-mail, file,or whatever you are looking for in the Search box. Vista searchesyour computer. The results of the search appear on the Start menu.When you see the program you are looking for, you can click theprogram name to open the program.

Is there a menu that lists all my programs?

Fig. 6.9 The Search Box


1. Click the Start button. The Start menu appears.

2. Click All Programs. A listing of programs and program foldersappears.

3. Click a program to open a program, or click a folder to opena folder and then click the program name. Vista starts theprogram.

Note: You may not be able to view all of your programs on the screen at onetime. Click and drag the scrollbar up or down to change which programs are

in view

42


Fig. 6.10 Customize Start Menu


Can I customize the Start menu?

You can customize the Start menu to suityour personal style. If you right-click theStart menu, a context menu appears (acontext menu performs an action relatedspecifically to the object you click). You canclick an option on the context menu toperform all of the actions discussed in thenext several questions.

Fig. 6.11


How do I add a program to the first pageof the Start menu?

1. Find the program name in the AllPrograms list.

2. Right-click the program name. A contextmenu appears.

3. Click Pin To Start Menu. The programappears on the first page of the Startmenu above the horizontal line.

43


How do I remove a program from the first page of the Startmenu?

1. Right-click the program name. A context menu appears.

2. Click Unpin From Start Menu. Vista removes the program from the firstpage of the Start menu.

If the program is located below the horizontal line, right-click the programname and then click Remove from This List.

How do I copy an item that is located on the Start menu orthe Program menu?

1. Right-click the item. A context menu appears.

2. Click Copy. Vista copies the program.

You can paste the copy to your desktop to create a desktop shortcut.

1. Right-click your desktop.

2. Click Paste. Vista creates a desktop shortcut.

How do I rename an item on the Start menu or the Programmenu?


2. Click Rename. Vista highlights the name.

3. Type the new name.

4. Press Enter. Vista changes the name.

How can I quickly locatefiles and folders?

You can use the Vista Searchfeature to locate documents,folders, pictures, music, and e-mails that are located on yourcomputer. You can also use theVista Search feature to locate adocument that includes aparticular word or phrase.When you click Search on theStart menu, the Search windowappears. A search field islocated in the upper-rightcorner of the window. In thesearch field, type the name ofthe file or folder you are lookingFig. 6.12 Locate files and folders


44


for, the date it was last modified, or even the author of the file. As you type,Vista searches for the file. Vista also provides you with a several options tonarrow your search. You can click All to search everything, E-mail to searche-mail, Document to search documents, and so on.

1. Click the Start button.

2. Click Search. The Search dialog box appears.

3. Type the filename, the folder name, the date the file was last modified, orthe author of the file in the Search field. As you type, Vista attempts to locatethe file. The results of the search appear in the window. You can click thefilename to open the file.

By default, vista searches indexed locations. Indexed locations are locationsthat are stored in your Personal folder. To close the Search window, click theX in the upper-right corner.

What does the Advanced Search option do?

In the Search Explorer window, youcan click the button next to thewords Advanced Search to displayseveral options with which you canrefine your search. The advancedsearch option enables you tosearch by date, location, file size,or property.

Fig. 6.14


Fig. 6.13 Advance Search option


45


Field Entry Type

Date Find any file that was created or modified on, before, or after a specifieddate.

Location Specify where you want to look. Indexed locations are locations that arestored in your Personal folder.

Size Specify that you want to look for files that are above or belowa certain size.

Property Limit your search to files that have a specific name, tag, orauthor.

To close the Search window, click the X in the upper-right corner.

What is the Most Recently Used Document list?

As you work, Windows Vista tracks the files and programs you have used. Itlists these files and programs on the Most Recently Used Document list. To viewthe list:


2. Click Recent Items on the right side of the Start menu. A list of recent filesand programs appears.

To open a file listed on the Most Recently Used Document list, click thefilename.

How do I set the number of files that display on my MostRecently Used Document list?

1. Right-click the Start button. A context menu appears.

2. Click Properties. The Taskbar and Start Menu Properties dialog box appears.

3. Click the Start Menu tab.

4. Click Customize. The Customize Start Menu dialog box appears.

5. Type the number of files you want Vista to display in the Number of RecentPrograms to Display field. You can enter any number between 0 and 30.

6. Click OK. The Customize Start Menu dialog box closes.

7. Click Apply.

8. Click OK. Taskbar and Start Menu Properties dialog box closes and Vistaresets the number of files that display on the Most Recently Used Documentlist.

How do I disable my Most Recently Used Document list?

1. Right-click the Start button. A context menu appears.

2. Click Properties. The Taskbar and Start Menu Properties dialog box appears.

3. Click the Start Menu tab.

4. Deselect Store and Display a List of Recently Opened Files.

46



5. Deselect Store and Display a List of Recently Opened Programs.

6. Click Apply.

7. Click OK. Vista clears and stops maintaining your most recently useddocument list.

Where are the games?

Several games are included with Windows Vista. To access the games:

1. Click the Start button, which is located in the lower-left corner of the screen.The Start menu appears.

2. Click Games. The Games Explorer window appears.

3. Double-click the game you want to play. The game starts.

How do I change the date and/or time that displays on mycomputer?

You can use the Date and Time dialog box to change both the date and thetime your computer displays.


2. Click Control panel. The Control Panel appears.

3. Click Clock, Language, and Region. The Clock, Language, and Regionpane appears.

4. Click Set Time and Date. The Time and Date dialog box appears.

5. Click Change Date and Time. The User Account Control dialog box mayappear, if so click Continue. The Date and Time Settings dialog boxappears.

Click the day of the month you want.

To change the day of the month:

To change the month:

Fig. 6.15

47


1. Click the month and year. All of the months of the year display.

2. Click the month you want. Vista changes the month.

To change the year:© CMS INSTITUTE 2012

1. Click the month and year. All the months of the year appear.

2. Click the year. A list of years appears.

3. Click the year you want. If you do not see the year you want, use the arrowkeys on your keyboard to scroll forward or backward through the list.

4. Click OK.

How do I change my Time Zone?


2. Click Control Panel. The Control Panel window appears.

3. Click Clock, Language, and Region. The Clock, Language, and Regiondialog box appears.

4. Click Change the Time Zone. The Date and Time dialog box appears.

5. Click Change Time Zone.

6. Click the down-arrow on the Time Zone field and then select the correcttime zone.

7. Click OK. The Time Zone Settings dialog box closes.

8. Click OK. The Date and Time dialog box closes. Vista changes the timezone on your computer.

If you want your computer to automatically adjust for daylight savings time,click the Automatically Adjust Clock for Daylight Savings Time checkbox.

How do I install a new printer?

A USB port is a socket on your computer that allows you to plug devices suchas a printer, digital camera, or scanner into your computer. If your printer can

Fig. 6.16

48


be connected to your computer via a USB port, Vista may be able toautomatically install your printer. To add a network, Bluetooth, or wirelessprinter:



3. Click Hardware and Sound. The Hardware and Sound window appears.

4. Click Add a Printer. The Add Printer Wizard appears.

5. Click Add a Network, Wireless, or Bluetooth. The Add Printer Wizard findsall available printers.

6. Select the printer you want to install.

7. Follow the steps outlined by the wizard to complete the installation.

How do I cancel a print job?




4. Click Printers. The Printers window appears.

5. Double-click the printer you are using. The printer's dialog box appears.

6. Click the job you want to stop. If you want to stop more than one job, holddown the Ctrl key while you click the additional jobs.

7. Click Document, which is located on the menu bar. A drop-down menuappears.

8. Click Cancel. You asked if you are sure you want to cancel the print job.

9. Click Yes. Vista cancels the print job.

When you start a print job, a print icon may appear on the taskbar in thenotification area. You can click the icon to open the printer's dialog boxmention in step 5.

How do I cancel every print job?





5. Double-click the printer you are using. The printer's window appears.

6. Click Printer, which is located on the menu bar.

7. Click Cancel All Documents. The document you are printing may finish,but Windows Vista cancels all other documents.

49


How do I temporarily stop selected jobs from printing?






6. Right-click the document you want to pause. A menu appears.

7. Click Pause Printing. Vista pauses the printing of your document.

How do I restart print jobs I temporarily stopped?




4. Click Printer. The Printers window appears.

5. Double-click the printer you are using. The Printer window appears.

6. Right-click the document that you want to resume printing. A menu appears.

7. Click Resume. The document starts printing again.

What is a desktop shortcut?

A desktop shortcut, usually represented by an icon, is a small file that pointsto a program, folder, document, or Internet location. Clicking on a shortcuticon takes you directly to the object to which the shortcut points. Shortcut iconscontain a small arrow in their lower-left corner. Shortcuts are merely pointers;deleting a shortcut does not delete the item to which the shortcut points.

How do I create a desktop shortcut?

If the item is located on the Start menu:

1. Click Start. The Start menu appears.

2. Locate the item to which you want to create a shortcut. If the item is locatedon a submenu, go to the submenu.


4. Click Send To. A submenu appears.

5. Click Desktop (Create Shortcut). Vista creates a shortcut to the item.

If the item is visible in the Windows Explorer:1. Open Windows Explorer.2. Locate the item for which you want to create a shortcut.3. Right-click the item. A context menu appears.4. Click Send To. A submenu appears.5. Click Desktop (Create Shortcut). Vista creates a shortcut to the item

50


How do I createa desktopshortcut to aWeb page?


Fig. 6.17

If you are usingInternet explorer:

1. Click the iconthat precedes theURL on theaddress bar.

2. Drag the icon toyour desk top.Vista creates theshortcut.

Now, when you clickon the shortcut, theWeb page will open.

How do I turn a Weblink into a desktopshortcut?

1. Click the link inyour browserwindow (usuallyunderlined text)and drag it to thedesktop. An iconappears on yourdesktop.

2. Click the icon togo directly to thelink's destination.If your browser isnot open, clickingthe icon starts thebrowser.

How does theCreate ShortcutWizard work?

Fig. 6.17 Create a desktop shortcut to a Web page


51


You can use the Create Shortcut Wizard to add a shortcut to your desktop.

1. Right-click the desktop. A context menu appears.

2. Click New. A submenu appears.

3. Click Shortcut. The Create Shortcut dialog box appears.

4. Type in the location of the item to which you want to create a shortcut.Alternatively, browse to find the item.

5. Click Next. The next Create Shortcut dialog box appears.

6. Accept the default name or type in a new name.

7. Click Finish. Vista creates the shortcut.

How do I rename a desktop shortcut?

The name of the desktop shortcut displays below its icon. For example, if youcreate a shortcut to the program Microsoft Word, the name Microsoft Worddisplays below the icon. To rename a shortcut:

1. Right-click the shortcut. A context menu appears.

2. Click Rename.

3. Type a new name.

4. Press Enter. Vista renames the icon.

I have a shortcut that opens a program on my desktop. How do I add it tothe Start menu?

1. Right-click the shortcut icon. A menu appears.

2. Click Pin To Start menu. The program appears on the Start menu, abovethe horizontal line.

How do I change the icon associated with an object on the desktop?

1. Right-click the icon. The context menu appears.

2. Click Properties. The Properties dialog box appears.

3. Click the Change Icon button. The Change Icon dialog box appears.

4. Click the icon of your choice.

5. Click OK. The Change Icon dialog box closes.

6. Click Apply.

7. Click OK. Vista closes the Properties dialog box. Vista changes the icon.

Note: Not all icons can be changed. If you do not see the Change Icon buttonor if the change icon button is dimmed, the icon cannot be changed.

How do I delete a desktop shortcut?

1. Click the shortcut.

2. Press the Delete key. Vista asks if you are sure you want to delete the

52


shortcut.

3. Click Yes.

Remember, shortcuts have an arrow in the lower-left corner. If the icon youdelete does not have an arrow in the lower-left corner, it is not a shortcut anddeleting the icon deletes the object.

What is wallpaper?

Wallpaper is the background that displays on your desktop.

How do I change mywallpaper?


2. Click Control Panel,which is located on theright side of the Startmenu. The Control panelappears.

3. Click Change theDesktop Background. Itis l is ted underAppearance andPersonalization.

4. Select the wallpaper youwant from the ones that

appear or click the down-arrow in the picture location field to select anotherwallpaper category. Note: If you would like to display an image youcreated, you can click Browse to find the image.

5. Click to select how you want your image to appear on the screen. Choosefrom the following:

Option ExplanationCenter Place the image in the center of the screen.Tile Have the image display as tiles across and down the screen.Stretch Stretch the image so the image covers the entire screen.

Fig. 6.19 Change myWallpaper


53


What is a font?

A font is a set of characters represented in a single typeface. Each characterwithin a font is created by using the same basic style.

Can you explain font size?

Fonts are measured in points. There are 72 points to an inch. The number ofpoints assigned to a font is based on the distance from the top to the bottomof its longest character.

How do I install a new font?

You must purchase or otherwise obtain the font you want to install. Then:


2. Click Control Panel.

3. Click Appearance and Personalization.

4. Click Install or Remove a Font, which is located under Fonts. The Fontswindow appears.

5. Click File, which is located on the menu bar of the Fonts window. Press theAlt key if you do not see the menu bar.

6. Click Install New Font.

7. Specify the drive and folder where the font you want to install is currentlylocated. The fonts appear in the List of Fonts box.

8. Highlight the font you want to install.

9. Select Copy Fonts To Fonts Folder (this puts a copy of the font you areinstalling in the Fonts folder).

10.Click Install. If you are prompted for permission to continue, click Continue.Vista installs the font.

11.Click Close. The Add Fonts dialog box closes.

What is the Character Map?

The Character Map displays the characters available in a selected font. To viewthe Character Map dialog box:


2. Click All Programs. The All Programs menu appears.

3. Click Accessories. A submenu appears.

4. Click System Tools. A submenu appears.

5. Click Character Map

54


The dialog box shown here appears

6. Select a font from the Font field drop-down menu. The characters of thefont appear in the boxes in the center of the window.

7. Click a character box to display an enlarged version of the character.

8. Double-click a character to send the character to the Characters To Copyfield.

9. Click Copy. Vista places the character on the Clipboard. You can pasteit into other programs.

Note: You can send multiple characters to the Characters to Copy field. Clickthe Copy button to move the Characters To Copy field contents to theClipboard.


Fig. 6.20 The CharacterMap

55


What are drives?

Drives are hardware components used to store data. Almost all computerscome with at least two drives: a hard drive (for storing large volumes of data)and a CD or CD/DVD drive (for storing smaller volumes of data that you caneasily transport from one computer to another). The hard drive is typicallydesignated the C:\ drive, and the CD drive is typically designated the D:\ drive.If you have an additional internal drive, it may be designated the A:\ drive.If your hard drive is partitioned (divided into several parts) or if you haveadditional drives, the letters E:\, F:\, G:\, and so on are assigned.

What are folders and files?

Folders are used to organize the data stored on your drives. A file is a collectionof related information or a computerized document. The files that make upa program are stored together in their own set of folders. When you createfiles, a good idea is to organize them in folders and to store files of a likekind in a single folder. Microsoft recommends that you store your documentsunder the Documents folder, your pictures under the Pictures folder, and yourMusic under the Music folder.

How does Vista organize files and folders on drives?

Vista organizes folders and files in a hierarchical system. The drive is thehighest level of the hierarchy. You can put all of your files on a drive withoutcreating any folders, but that is like putting all of your papers in a file cabinetwithout organizing them into folders. It works fine if you have only a few files,but as the number of files increases, there comes a point at which things aredifficult to find. To avoid this, create folders and put related material togetherin folders.

A diagram of typical drives and how they are organized is shown here.

At the highest level, you have some folders and perhaps some files. You canopen any of the folders and put additional files and folders into them. Thiscreates a hierarchy.

Will you explain Explorer windows?

You use Explorer windows to search for and manage the files on your computer.When you open your Personal folder or click Documents, Pictures, Music,Games, Computer, or Network on the Start menu, an Explorer window appears.Explorer windows consist of several parts: the Forward and Back buttons, theAddress bar, the Instant Search box, the Command bar, the Menu bar, theNavigation pane, the File List, the Headings, the Preview pane, and the Detailspane.


Fig. 6.21

56



Fig. 6.22 The WindowsExplorer No Area No Area

1 Forward and Back buttons 2 Address bar

3 Instant Search box 4 Command bar

5 Menu bar 6 Navigation pane

7 File List 8 Headings

9 Preview pane 10 Details pane

buttons

Area Description

Forward & Back You can use the Forward and Back buttons to moveforward and backward through your searches.

Address Bar The Address bar provides drop-down menus for thecurrent navigation path. A navigation path is the sequenceof folders on a drive that you must open to get to the filefor which you are looking. The folders are ordered fromthe highest to lowest point in the hierarchy. You can usethe Address bar to move up or down the navigation path.You can also use the Address bar to find recently visitedWeb sites and prior searches.

57


Instant Search Box In the Instant Search box, you can search for folders andfiles on your computer by typing the folder or filename.You can also use the Search box to find all documentsthat contain a particular word or phrase or have aspecific property.

Command Bar By using the Command bar, you can perform a varietyof tasks related to managing and organizing the files onyour computer. For example, you can use the Commandbar to cut, copy, and paste files.

Menu Bar For the most part, the Menu bar has the same featuresas the Command bar. By using the Menu bar, you canperform a variety of tasks that relate to managing andorganizing the files on your computer. Because theCommand bar and the Menu bar perform many of thesame functions, by default the Menu bar does not display.To display the Menu bar, press the Alt key.

Navigation Pane You can use the Navigation pane to open a folder. Foreasy access, commonly used folders are listed at the topof the Navigation pane.

File List When you open a folder, Vista lists the contents of thefolder in the File List.

Headings Headings appear at the top of the File List. Headingsidentify the file properties.

Preview Pane For programs that support this feature, the Preview paneshows you the contents of a document without openingthe document.

Details Pane You can use the Details pane to view, add, and/or changea document's properties. Properties are characteristicsthat are either automatically assigned to a file or assignedto a file by you. Properties include such things as the datethe file was last modified, the author, and the documentcategory.

Area Description

How do I tell Explorer which parts of the Explorer window todisplay?

Start by opening an Explorer window:


2. Click the name of your Personal folder, Documents, Pictures, Music, Games,or Computer.

3. An Explorer window opens.

Select the parts you want to display:

58


1. Click Organize on the Command bar. A menu appears.

2. Click Layout. A submenu appears.

3. Click to select all the options you want to appear in the Explorer window.Choose from Menu Bar, Details Pane, Preview Pane, and Navigation Pane.

Note: Choosing Menu Bar causes the menu to permanently display.

What is a Personal folder?

When you log on to Windows Vista for the first time, you must create anaccount. Thereafter, you log on to your computer by clicking the account name.After you create an account, Vista creates a Personal folder for you. Vista storesthe folders you will use most often, such as the Documents, Pictures, and Musicfolders, under your Personal folder. Vista gives your Personal folder the samename as your account name. For example, my account name is DeniseEtheridge; Vista named my Personal folder Denise Etheridge. Clicking yourPersonal folder name opens an Explorer window. I will use the Personal folderto illustrate how to use an Explorer window

How do I open my Personalfolder?


2. Click the name you entered whenyou created your account. Thename is located at the top of theStart menu's right column.

When you open the Personal folder,an Explorer window similar to theone shown here appears.

How do I open a folder?

To open a folder that is locatedunder the Favorite Links area of theNavigation pane, click the foldername. The contents of the folderappear in the File List.

If the folder you are looking fordoes not appear under FavoriteLinks:

1. Click Folders, which islocated in the lower-left corner of


Fig. 6.23 Open My Personal Folder

59


the Navigation pane. Additionalfolders appear. The folders arestructured in a hierarchy as theywere in Windows XP, which is theprevious version of the Windowsoperating system.

2. Click the folder you want toopen.

To close the Folders area, click theword Folders again. It may havemoved to the top of the Navigationpane.

How do I open a file or a folder thatis located in the File List?

When you open a folder, the folders

and files contained in the folder appear in the File List. To open a file, doubleclick the filename. You can also open the folders that appear in the File Listby double-clicking them.

How do I create a new folder?

To create a new folder:

1. Locate the folder in which you want to create the new folder.

2. Click Organize on the Command bar.

3. Click New Folder. Vista creates a new folder.

4. Type a name for the folder.

5. Press Enter. Vista changes the name of the folder.

Can I search for files and folders?

To search for a file or even for a word that is contained in a file, use the InstantSearch box located in the upper-right corner of your Personal folder:

1. Type what you are searching for in the Instant Search box. As you type, Vistadisplays the results of the search in the File List.

2. Double-click a filename to open the file.

Can I save a search?

You can save a search so you can use it again.

1. Create your search.

2. Click Save Search. The Save As dialog box appears.


Fig. 6.24 Navigation Pane

60


3. Type the name you want to give your search.

4. Click Save. Vista saves the search in the Searches folder.

To run your search again:

1. Click Searches in the Navigation pane. The Searches folder appears.

2. Double-click the search you want to run. Vista runs the search.

How does the Address bar work?The Address bar is located in the upper-left corner of an Explorer window. Youcan use the Address bar to navigate through your folders. To open a folder

1. Click the arrow next to thefolder name. A list of thefolders in that folder appears.

2. Click the folder you want toopen.

You can move up and down thefolder hierarchy (path) by clickingfolder names.

Can I add folders andsaved searches to theNavigation pane?

You can open the folders andexecute the searches on theNavigation pane simply by

clicking them. If you have a folder or search you access frequently, you maywant to add it to the Navigation pane.

1. Locate the folder or search you want to add.

2. Click and drag the folder or search to the Navigation pane. You can nowclick the folder name or the search to open the folder.

If you use a saved search frequently, you can also add the search to theNavigation pane by clicking and dragging.

How do I display the Menu bar?

By default, the Menu bar does not appear. To temporarily display the Menubar, press the Alt key. To hide the Menu bar, press the Alt key again. You canalso choose to display the Menu bar permanently.

1. Click Organize. A menu appears.

2. Click Layout. A submenu appears.

3. Click Menu Bar. A check mark appears next to Menu Bar. The check mark


Fig. 6.24 The Address Bar

61


indicates Menu Bar is selected. When Menu bar is selected, the menu barpermanently displays.

Will you explain Explorer views?

Views control how Explorer windows display information in the File List. TheViews option on the Explorer Command bar provides the following choices:Extra Large Icons, Large Icons, Medium Icons, Small Icons, List, Details, andTiles.

" Tiles view and Icon views display icons to represent drives, folders, and thecontents of folders. You can choose from icons that are large, small, ormedium in size.

" List view displays all of the files and folders without displaying the properties.

" Details view displays the filename and associated properties you haveselected to display

To change the view

1. Click the down-arrow next to Views on the Command bar. A menu appears.

2. Drag the slider to select the view you want.

What are file properties?

File properties are pieces of information that are associated with a file. Forexample, Vista automatically saves the date and time each time you modifya file. You can also associate properties with a file. For example, you can placeall files associated with sales in a category called sales.© CMS INSTITUTE 2012

Fig. 6.25 Explorer Command Bar

62


To see a list of the propertiesyou can assign to a file:

1. Right-click a Heading. Alis t of propert iesappears.

2. Click More if you do notsee the property forwhich you are looking.The Choose Detailsdialog box appears.

3. Click to select theproperties you want touse. A check markappears next to selectedproperties.

You can search for files by entering the property in the Instant Search box. Whenyou click a filename, the file properties display at the bottom of the Explorerwindow in the Details pane. To change a property listed in the Details pane:

1. Click in the property'sfield.

2. Type the property youwant to assign.

What is filtering?

When you filter a folder,you see only the files thathave the property for whichyou are looking. You canfilter by any file property.For example, by using afilter, you can view all thefiles by selected authors.You can apply multiplefilters to a single folder. Tofilter:


Fig. 6.27 The Propertiesyou can assign to a file


Fig. 6.28 The Properties you can assign to a file

63


1. Click the down-arrow next to aHeading. A context menuappears.

2. Click the property by whichyou want to filter. For example,if you want to filter by author,click the author's name. A checkmark next to the filter indicatesthat the property is selected.Vista only displays the filesthat have the selectedproperties.

3. Click the down-arrow next toanother Heading to filter bythat Heading and then repeatstep 2.

To remove a filter:

1. Click the down-arrow next to the filtered Heading.

2. Click to remove the check mark next to each filtered property.

What is stacking?To show all the files with a particular property together, you use stacking. Forexample, you can group all the files by a particular author together.

1. Click the down-arrow next tothe property by which you wantto stack files. A context menuappears.

2. Click the Stack option at thebottom of the menu. Vistastacks together all the files thathave the same property.

3. Click the Stack icon. Vistaexpands the stack so you cansee the files.

What is the purpose of theComputer option on the Startmenu?

The Computer option enables you


Fig. 6.29 Filtering


Fig. 6.30 Stackig

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to open the Explorer Computer window to view the drives on your computerand manipulate folders and files. The Explorer Computer window works muchlike the Personal folder. You can cut, copy, paste, rename, and delete foldersand files. By selecting the Computer option, you can perform many of thefunctions you performed by using Windows Explorer in previous versions of theWindows operating system, such as Windows XP.

To access the Explorer Computer window:


2. Click Computer. Computer is located on the right side of the menu.Information about your computer becomes available to you.

Alternatively, you can open the Explorer Computer Window by holding downthe Windows Logo key while typing e (Windows-e).

How does the Preview pane work?If you have a file that was created in a program that supports Preview mode,in Explorer windows you can see the contents of the file without opening thefile. To see a preview, click the filename. A preview appears in the Preview pane.How do I delete a file or folder?To delete a file or folder:

1. Right-click the file or folder you want to delete. A context menu appears.

2. Click Delete. Vista asks, "Are sure you want to move this file to the RecycleBin?"

3. Click Yes. Vista places the file or folder in the Recycle Bin.

How do I copy a file or folder?You can make a copy of a file orfolder and place the copy inanother location. Placing a file orfolder in another location is atwo-step process. First you makethe copy and then you paste thecopy in the new location. Whenyou execute a Copy command,Vista stores the information youcopied in a storage area calledthe Clipboard. Refer to thequestion "How do I paste a file orfolder?" to learn how to paste.

1. Right-click the file or folder


Fig. 6.31 Preview Pane

65


you want to copy. A context menu appears.

2. Click Copy. The file or folder is now on the Clipboard.

How do I cut a file or folder?Cutting enables you to move a file to a new location. Moving a file to a newlocation is a two-step process. First you remove the file from its current locationby cutting it. Then you paste it in the new location. When you execute a Cutcommand, Vista stores the information you cut in a storage area called theClipboard. Refer to the question "How do I paste a file or folder?" to learn howto paste.

1. Right-click the file or folder you want to cut. A context menu appears.

2. Click Cut. The file or folder is now on the Clipboard.Note: Cutting differs from deleting. When you cut a file, the file is placed onthe Clipboard. When you delete a file, the file is sent to the Recycle Bin.

How do I paste a file or folder?Pasting places information on the Clipboard in the location you specify. Topaste a file or folder:

1. After copying or cutting the file, right-click in the File list to which you wantto paste. A context menu appears.

2. Click Paste. Vista pastes the file in the new location.

How do I rename a file or folder?

1. Right-click the file or folder. A context menu appears.

2. Click Rename.

3. Type the new name.

4. Press Enter. Vista changes the name of the file or folder.

What is a screen saver?Computer monitors display images by firing electron beams at a phosphor-coated screen. If the same image stays on the screen too long, the image mayleave a permanent imprint on the screen. Screen savers help prevent this byproviding a constantly changing image.How do I select a screen saver?

1. Right-click anywhere on the Windows desktop. A context menu appears.

2. Click Personalize. The Personalize window appears.

3. Click Screen Saver. The Screen Saver Settings dialog box appears.

4. Click the down-arrow in the Screen Saver field. A list of screen saversappears.

5. Click to select the screen saver you want to use. A preview of the screensaver appears in the Screen Saver Setting dialog box.

66


6. In the Wait field, set the number of minutes of inactivity before the screensaver starts.

7. Click Apply.

8. Click OK. Vista sets your screen saver.

What is a window?A window is an area on your desktop within which a Windows-based programruns.

Will you explain the parts of a window?I will use WordPad as an example. WordPad is a word-processing programthat comes with Windows Vista. To access WordPad:


2. Click All Programs. The All Programs menu appears.

3. Click Accessories. The Accessories submenu appears.

4. Click WordPad. WordPad starts

No Area No Area

1 Control box 2 Menu bar

3 Title bar 4 Minimize

5 Maximize 6 Close button

7 Command bar 8 Border

9 Status bar 10 Work area


Fig. 6.32 Application Window

67


Part Description

Control box Provides a menu that enables you to restore, move, size, minimize,maximize, or close a window.

Menu bar Displays the program's menu. You can use the menu to sendcommands to the program.

Title bar Displays the name of the current file and the name of the currentprogram.

Toolbar Displays icons you can click to send commands to the program.Toolbars generally appear directly below the menu, but you can dragthem and display them along any of the window borders.

Minimize button Click to temporarily decrease the size of a window or remove awindow from view. While a window is minimized, its title appears onthe taskbar.

Maximize button Click to make the window fill the screen.

Close button Click to exit a window or close a program.

Command bar Displays icons you can click to send commands to the program.

Border Separates the window from the desktop. Drag a window's bordersoutward to expand it and inward to contract it.

Status bar Provides information about the status of your program.

Restore button Click to restore a minimized window to its former size.

Can I have more than one window open at a time?

You can have as many windows as you want open at the same time.

How do I switch between windows?

If you have several windows open at the same time, the window on top is thewindow with focus. You can only interact with the window with focus. To changewindows, do any one of the following:

" Click anywhere on a window to change the focus to that window.

" Hold down the Alt key and press the Tab key (Alt-Tab). A preview of all openwindows appears. While holding down the Alt key, click the Tab key untilyou have selected the window to which you want to change.

" All active files display on the taskbar. Click the taskbar button for thewindow you want to have focus.

How do I move a window around on my desktop?

Left-click the window's title bar and drag the window.

What does it mean to "cascade your windows"? What does itmean to "show windows side by side"?

Showing your windows side by side is another way of organizing your windowson your desktop. When you show your windows side by side, Windows Vista

68


places each window on the desktop in such a way that no window overlapsany other window. The windows display side by side.

How do I show my windows side by side?

1. Right-click the taskbar. A menu appears.

2. Click Show Windows Side by Side. Vista displays your windows side-by-side.

What are scrollbars?

In many programs, if the contents of the work area do not fit in the window,scrollbars appear. A vertical scrollbar appears at the right side of the windowand a horizontal scrollbar at the bottom of the window. The vertical scrollbarprovides a way to move up and down. The horizontal scrollbar provides a wayto move from left to right and from right to left.The scroll box indicates where you are in your document. If the scroll box isat the top of the scrollbar, you are at the top of the document. If the scroll boxis in the center of the scrollbar, you are in the center of the document.

How do the scrollbars work?

To move up and down one line at a time:

" Click the arrow at either end of the vertical scrollbar.

To move from side to side:

" Click the arrow at either end of the horizontal scrollbar.

To move approximately one window at a time:

" Click above the scroll box to move up.

" Click below the scroll box to move down.

To scroll continuously:

" Click the appropriate arrow and hold down the mouse button.

To move to a specific location:

" Left-click the scrollbar and hold down the left mouse button until you arriveat the location. For example, if you want to go to the center of the document,click the center of the scrollbar and hold down the left mouse button.

" Or, drag the scroll box until you arrive at the desired location.

What is an icon?An icon is a small image. Icons help you execute commands quickly. Commandstell the computer what you want the computer to do. To execute a commandby using an icon, click the icon.

What is a menu?Menus provide a way for you to send commands to the computer (tell thecomputer what you want the computer to do). When you open a window, menu

69


options are listed from left to right on the menu bar, just below the title bar.When you click a menu item, a drop-down menu appears. Select the commandyou want to execute from the drop-down menu. An ellipsis after a drop-downmenu item signifies that there are additional options; if you select that option,a dialog box appears.

What is a shortcut key?You can use shortcut keys to execute a command quickly by pressing keycombinations instead of selecting the commands directly from the menu orclicking on an icon. When you look at a menu, most of the options have oneletter underlined. You can select a menu option by holding down the Alt keyand pressing the underlined letter. You can also make Alt-key selections fromdrop-down menus and dialog boxes.In this tutorial and on this Web site, we use the following notation: a key namefollowed by a hyphen and a letter means to hold down the key while pressingthe letter. For example, "Alt-f" means to hold down the Alt key while pressing"f" (this opens the File menu in many programs). As another example, holdingdown the Ctrl key while pressing "b" (Ctrl-b) bolds selected text in manyprograms. In some programs, you can assign your own shortcut keys.

What is a selection?A selection is a highlighted area on which you can perform a command. Forexample, if you are using a word-processing program, you can highlight aword and then execute the Underline command to underline the highlightedword.

How do I make a selection?

1. Left-click where you want to start your selection.

2. Hold down your left mouse button and drag the mouse until you havehighlighted the area you want.

Or

1. Left-click where you want to start your selection.

2. Hold down the Shift key while you use the arrow keys to highlight the areayou want.

Note: Typing over highlighted text replaces the old text with the new text you type.

Can you explain cut, copy, and paste?The Cut, Copy, and Paste commands are used by almost every Windowsprogram and perform more or less the same function in each of them. Youcan cut, copy, and paste programs, disks, and text, to name just a few things.Cut: When you cut something, you delete it from its current location and saveit to the Clipboard. Information saved to the Clipboard stays there until newinformation is either cut or copied. Each time you execute Cut or Copy, you

70


replace the old information on the Clipboard with whatever you just cut orcopied. While information is on the Clipboard you can paste it as often asyou like.Copy: Copy is similar to Cut except you do not delete the original item. Whenyou copy something, a copy of the item is saved to the Clipboard. Informationstored on the Clipboard stays there until new information is either cut or copied.Each time you execute Cut or Copy, you replace the old information on theClipboard with whatever you just cut or copied. While information is on theClipboard you can paste it as often as you like..Paste: You can place Clipboard information wherever you like. When youexecute the Paste command, you place the information you have cut or copiedwherever your cursor is located.Clipboard: The Clipboard is the storage area for items you have cut or copied.Each time you execute Cut or Copy, you replace the old information on theClipboard with whatever you just cut or copied. You can paste Clipboardinformation as often as you like, until you replace it with something else.There are three major methods of cutting, copying, and pasting: using themenu, using keyboard shortcuts, and using icons. In most programs, they workexactly as described here.Using the Menu:

Cut

1. Select what you want to cut.

2. Click Edit, which is located on the menu bar. A drop-down menu appears.

3. Click Cut.

Paste

1. Place the cursor at the point where you want to place the information thatis currently on the Clipboard.

2. Click Edit. A drop-down menu appears.

3. Click Paste.

Copy

1. Select what you want to copy.

2. Click Edit, which is located on the menu bar. A drop-down menu appears.

3. Click Copy.

Using Keyboard Shortcuts:

Cut

1. Select what you want to cut.

2. Press Ctrl-x.

71


Paste

1. Place the cursor at the point where you want to place the information thatis currently on the Clipboard & Press Ctrl-v.

Copy

1. Select what you want to copy, and Press Ctrl-c.

Using Icons:

Cut

1. Select what you want to cut and Click the Cut icon.

Paste

1. Place the cursor at the point where you want to place the information thatis currently on the Clipboard.

2. Click the Paste icon.

Copy

1. Select what you want to copy.

2. Click the Copy icon.

Are there any universals that apply to almost all programs?Following is a list of commands that appear in many, but not all programs.Check each program's documentation for information specific to the program.Note: I use the following convention to indicate a menu path: View > Toolbars.When you see View > Toolbars, it means choose View from the menu bar andselect Toolbars from the drop-down menu.

Cascading is a way of organizing windows on your desktop. Cascadingwindows fan out across your desktop, with the title bar of each window showing.

How do I cascade my windows?


2. Click Cascade Windows.

3. Vista cascades the open windows.

What does it mean to "stack your windows"?

Stacking is a way of organizing your windows on your desktop. When you stackyour windows, Windows Vista places each window on the desktop in such away that no window overlaps any other window. The windows are stacked oneon top of the other.

How do I stack my windows?


2. Click Show Windows Stacked. Vista stacks your windows.

72


Icon Shortcut Key Menu Path Command Description

Ctrl-n File > New Create a new file.

Ctrl-o File > Open Open an existing file.

Ctrl-s File > Save Save the current file.

Ctrl-p File > Print Print the current file.

Ctrl-f Edit > Find Find text in the current document.

Ctrl-x Edit > Cut Cut (delete and place on Clipboard) the current

selection.

Ctrl-v Edit > Paste Place the material currently on the Clipboard

at the current location of your cursor.

Ctrl-c Edit > Copy Copy the current selection to the Clipboard.

Ctrl-z Edit > Undo Reverse the most recent command. Place the

program in the state it was in before

executing the last command.

Ctrl-y Edit > Redo Reverse the last undo. Place the program in

the state it was in before executing Undo.

Format > Font Apply a font to the current selection.

Format > Font Set the size of the font for the current selection.

Ctrl-b Format > Font Bold the current selection.

Ctrl-i Format > Font Italicize the current selection.

Ctrl-u Format > Font Underline the current selection.

Ctrl-l Left-align the selection.

Ctrl-r Right-align the selection.

Ctrl-e Center the selection.

Ctrl-j Justify the selection.

View > Toolbars Select the toolbars you want to display.

73


Will you explain how tosave a file?

I will use WordPad as an example.

1. Click File, which is located onthe menu bar. A drop-downmenu appears.

2. Click Save. If you have neversaved the file before, the Save

Field/Icon Entry

Address bar Select the folder to which you want to save the file.

Instant Search box Search for folders and files on your computer by typing the filename here.

File Name field Name your file by typing the name in this field.

Save As Type field Click to open the drop-down box and select a file type.

Browse Folders button Click to open an Explorer window in which you can perform all of theExplorer functions.

Save button Click to save your file.

Cancel button Click if you change your mind and do not wish to save your file.

As dialog box appears.

3. Click the down-arrow in the Save As Type field and then select the file typeyou want your file to have.

4. Type the name you want to give your file in the File Name field.

5. Click the Browse button and then use the Explorer window to change foldersif needed.

6. Click the Save button.

What is a dialog box?Whenever you see an ellipsis (…) after a menu option, selecting that optioncauses a dialog box to appear. You use dialog boxes to send commands tothe computer. Most dialog boxes provide an OK button and a Cancel button.Click the OK button if you are satisfied with your entries and you want to sendthe commands to the computer. Click the Cancel button if you change yourmind and do not want to send the commands to the computer.


Fig. 6.33 Save as DialogBox

74


What are tabs?

Some programs provide dialogboxes with several pages of options.You move to a page by clicking onits tab or by using Ctrl-Tab (holddown the Ctrl key while pressingthe Tab key to flip through thepages).

What are fields?You type entries into fields (also referred to as text boxes). For example, in theSave As dialog box, you type the name you want your file to have in the FileName field.


Fig. 6.34 Tabs


Fig. 6.35 Fields

75


What are list boxes?

List boxes provide multiple options from which you can choose. To make yourselection, simply click the option you want. In some list boxes, you can choosemore than one item. To choose multiple items, hold down the Ctrl key whileyou make your selections. If there are more options than can be displayed inthe box, a scrollbar appears on the list box. Use the scrollbar to view theadditional choices.

What is adrop-down orpull-downmenu?

Fields with a drop-down menu havea small downwar-

pointing arrow next to them. You click the arrow and a list of options appears.You select the option you want from the list. You can also open the drop-downmenu by holding down the Alt key and pressing the down-arrow.You can use the arrow keys to move up and down in a drop-down menu. Youcan also move to an item by typing the first few letters of the option.


Fig. 6.36 List Box


Fig. 6.37 Dropdown Menu

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What areradio buttons?

Windows Vista andprograms that rununder WindowsVista use radiobuttons to presenta list of mutuallyexclusive options.You can select onlyone of the optionspresented. Radiobuttons are usuallyround. A dot in themiddle indicatesthat the option isselected.

What are checkboxes?Checkboxes are another method for selecting options.You click the checkbox to select the item. An X or a checkmark appears in a selected box. You toggle checkboxeson and off by clicking in the box.

What is a slider?You use a slider to increase ordecrease a value. In the illustration,you increase a value by moving theslider toward the right; you decreasea value by moving the slider towardthe left.


Fig. 6.38 Radio Buttons


Fig. 6.39 Check Boxes


Fig. 6.40 Slider

77


What is a spinner?A spinner is a set of arrows located on the sideof a text box. You use the up-arrow to incrementa value and the down-arrow to decrement avalue. You can also type the value you wantdirectly into the text box.

Will youexplain theWindowsVista colorbox?Some programsallow you toadjust colors;for example,you can adjustthe color of textin someprograms. TheWindows colorbox provides 48basic colors.You select acolor by clicking

on that color's square. You can save 16 custom colors. To create a custom color,expand the window by clicking on the Define Custom Color button. A colormatrix box and a luminosity slider appear. Move the pointer in the color matrixbox horizontally to adjust the hue. Move the pointer vertically to adjust thesaturation. Use the luminosity slider to adjust the luminosity. The Hue, Saturation,Luminosity (HSL) values and Red, Green, Blue (RGB) values display at thebottom of the window. After you select a color, you can add the color to aCustom Color square by clicking the Add To Custom Colors button.The Color|Solid box may display two colors. The left side of the box displaysthe dithered color and the right side of the box displays a closely related non-dithered color. There are 256 non-dithering colors. Non-dithering colorsshould display the same on all computer monitors; consequently, Web


Fig. 6.42 Windows VistaColour Box


Fig. 6.41 Spinner

78


LAB EXERCISE 6.1 : Getting Familiar with Windows Operating System

Objective: To be familiar with the windows operating system

Tasks:1. know different flavours of Windows Vista2. working with files, folders, and windows explorer3. working with different applications and resources

79

Getting Familiar with the PCCMS COMPUTER INSTITUTECMS COMPUTER

INSTITUTE

7PC ENGINEERING

BASICSA personal computer is made up of many separate items. From the user’s pointof view, there is the system unit, the keyboard and the monitor.

The present day front view of the system unit is as shown in the fig. 7.1.

It shows the different bays or slots which are present and for what purpose theyare used. The 5.25 inch bays are normally used for devices like CD-ROM's,CD Writers etc. whereas the 3.5 inch bay is normally used for the floppy drive.

Nowadays there a few cabinet manufacturers which do provide a small windowfor the USB connector from the front side along with the connectors for themicrophone and the earphone as shown in fig. 7.1.

The present day backpanel of the system unit along with all the connectorsis as shown in the fig. 7.2. Although there are around 50 different connectors

all the connectors fit into one of theseven major types: DB, DIN,Centronics, RJ, BNC, audio, and USB.

In the back panel shown in the fig. 7.2,at the top right is a socket for thepower cord as well as a voltage selectorswitch which is used to select the voltagestandard followed.

Towards the left are the differentconnectors, out of which the first 2connectors are the mini DIN connectors.The mini-DIN connector or the PS/2connector as it is commonly referredto, is used for connecting the mouse.Below it are the two USB ports used toconnect the USB devices. Theconnectors below it are the DB

Fig. 7.1 Personal Computer System


51/4" bayforCD ROM'setc.

USB,Microphone&Earphoneconnectors

31/2" bayFloppyDrive

Getting Familiar with the PC

80

Getting Familiar with the PCCMS COMPUTER INSTITUTE

connectors. The first DB connector is for the serialport which is a 9-pin male connector used to connectdevices like mouse, modem etc. Then below it, thereis a 15-pin female VGA connector used to connectto the monitor. Beside the two DB connectors is aparallel port or the centronics port used to connectto the printer. Then there are the additional USBports and the RJ-45 connectors used to connect thepatched cord to the LAN card. Below these are thethree audio connectors which include onemicrophone jack used to connect the microphone,then there is the line out jack used to connect thespeaker and finally there is the line-in jack used toconnect any other input or MIDI devices.

In the illustration of the fig. 7.2 there is also aninternal modem which has two RJ-11 sockets one forthe phone jack i.e. for the phone instrument and theother for the line-in jack used to connect to thephone line coming in. The other extra slots arenothing but the expandability slots reserved forfuture use.

The front and the back panel of the system unitreferred above are just one of the commonly usedones which may differ according to the cabinet aswell as motherboard manufacturers.

Once the cover’s off, though, several more partsbecome visible. In most PC compatibles the power supply is positioned at therear right hand side of the system unit. It’s a metal-encased box, with coolingslots punched out of the casing. There are usually stickers on it to warn youabout the high voltages found inside. The job of the power supply is to convertthe raw AC mains to the stabilised DC voltages at plus and minus 5 and 12volts needed by the electronics of the PC.

The diskette drives are of course readily identifiable. The hard disk, often ishidden away inside the machine. All that can usually be seen of it is a die-cast metal casing, attached to which is a small circuit board, with two or threecables leading from it. Sitting at the bottom of the case is a large circuit boardwhich holds the expansion slots into which other circuit boards fit. This is knownas the system board or the motherboard. On most PCs the motherboardcontains the CPU, the main memory, and other circuits described later in thischapter. Many motherboards on the latest PCs contain serial and parallel I/


RJ45(LAN)Port

PS/2KeyboardPort

Power Cord Socket

VoltageSelectorSwitch

VGAPort

SerialPort

USBPorts

USBPorts

Microphone

Line-out

Line-in

Phone

Modem

Expandability Slots

ParallelPort

PS/2MousePort

Fig. 7.2 Back Panel ofPersonal Computer

81


O ports, and even the disk controller andvideo display adapter circuitry. Theadvantage of this is that the motherboardcan then have fewer expansion slots, sinceadd-in circuit boards are not needed forthese things. This allows the manufacturer tobuild a smaller computer.

Some PC designs have a passive backplane,which is essentially just a board containingexpansion slots. The system board proper -the CPU, memory and logic - are on aseparate board which plugs into one of theslots. The advantage of this approach is that

the manufacturer can make one basic design. He can then offer a range ofdifferent CPUs for different levels of performance, simply by plugging in adifferent system board.

BOARD COMPONENTSThe black, square or rectangular components mounted on the motherboardand expansion cards are integrated circuits (ICs). Each IC is made up ofthousands - often hundreds of thousands - of transistors, all etched on to asingle wafer or chip of silicon. The small, oblong ICs with seven or eight metallegs along each of the long sides, are known as dual-inline (DIL) or dual-inline-package (DIP) ICs. These are the basic building blocks of a computer.

Advances in technology have made it possible to build larger, more complexcircuits on a single chip. This technique is called large-scale integration (LSI).The microprocessor used in the latest high-performance PC compatibles is theVLSI technology and Pentium III and Pentium IV are all state-of-the-art examplesof VLSI technology.

It is now possible to build all the logic of the original PC, which used severaldozen discrete ICs, onto a couple of VLSI chips. This gives many advantages.The system board can be made smaller, reducing the overall size of thecomputer itself. Since the board requires fewer components it is quicker andcheaper to manufacture. Power consumption and heat dissipation are lower.This, together with the reduced component count, gives better reliability.

On the latest board designs you will probably see many small componentssoldered directly to the board. These are known as surface-mounted devices(SMDs). SMDs have become popular in the last couple of years. They lendthemselves extremely well to automated production lines, and therefore reducethe cost of board manufacture. The disadvantage is that they are difficult to


ISA

Lithium Battery

BIOS

SMPSConnector

Supportingchipset

Front PanelConnectors

Memory Bank

KeyboardConnector

ExpansionSlot

CPU

CacheMemory

PCI

Intel X86PCIchipset

Fig. 7.3 Motherboard withmajor components

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un-solder and replace by hand. This just rules out attempts at repairing faultyboards.

PROCESSORSThe CPU as described in the first unit of this module, is the part that makesa computer useful. It’s the bit that does most of the work. It reads the bytesof program instructions held in memory and obeys them, faithfully and very,very fast. The term central processing unit originated in the days of mainframes,when it described a very large box containing a lot of complex circuitry. In amicrocomputer like the PC, the CPU is a single integrated circuit chip containinga lot of complex circuitry. This chip is called a microprocessor. In the originalPC and XT, and the cheapest, slowest compatibles, the microprocessor usedis an Intel 8088 or 8086. In later, faster models, more powerful microprocessorsfrom the same INTEL family are used. These are, in order of power, the 80286,80386sx, 80386dx, 80486sx, 80486dx, 80486PCI chipset, Pentium, PentiumII and further. Each of these chips runs all the instructions of its less powerfulpredecessors, but is faster, and adds new features of its own.

MEMORY STORAGE

The two most important components in a microcomputer are the CPU and thememory. The CPU does the work. The memory is its scratch pad or work area.Every other part of the computer is there simply to get information to and fromthese two main components, the non-volatile storage such as disk drives, andthe outside world.

Memory is arranged as a linear array of 8-bit bytes, which may be used tohold either machine code instructions for the microprocessor or data. Each byteof memory has a unique address by which it may be accessed at random, andit is consequently known as random access memory, or RAM. Each byte of RAMcan hold a positive integer value in the range 0 to 255, a signed value in therange -128 to +127, or a single character in the extended ASCII characterset. In the PC family the character set includes the digits 0 to 9, all the lettersof the alphabet (in both upper and lower case), punctuation, 32 controlcharacters, and 128 special characters which include fractions, foreign alphabetsymbols, and line graphics for box drawing.

Two bytes together - known as a word - can be used to hold a positive integerin the range 0 to 65535, or a signed integer in the range -32768 to +32767.Larger groups of bytes may be used to represent larger numbers, includingfractional numbers or floating-point numbers.

Machine code instructions for an INTEL microprocessor may be one or morebytes in length. The instruction type is usually one or two bytes. This may befollowed by up to four bytes which are the data, or operand, for the instruction.

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This might be a constant value for use in a calculation or comparison, or theaddress of a location in memory from which data is to be read or written.

In the PC architecture, there is no differentiation between memory used forstoring program instructions and that used to hold data. Data and programcan be freely mixed in the same area of memory. It is up to the programmerto ensure that a program does not overwrite parts of itself with data, and thatthe CPU will never find itself trying to interpret bytes of data as programinstructions.

A common program error occurs when a block of data that is larger thanexpected overflows the area reserved for it and writes over adjoining programinstructions. When the processor comes to execute these instructions, the resultis usually disastrous. More sophisticated computer architectures separate thedata from the instructions, so that this sort of problem can’t occur.

Early microprocessors such as the Intel 8080 and Zilog Z80 used a 16-bitaddress bus, which allowed them to access up to 64k (65,536) bytes ofmemory. One of the original uses of microprocessor chips was in processcontrol applications such as automated machine tools, washing machinecontrollers and the like. The control software for this type of job was typicallyonly a few kilobytes in size. So 64k seemed like plenty of memory at the time.

The Intel 8086 was designed to be upwardly compatible with the 8080 andZ80, so that any computer that used it could make use of existing software.Also, the 8086 introduced 16-bit instructions and access to more memory, forthe benefit of more sophisticated software which would be developed later. The8086 can access upto 1Mb of memory, which again seemed like more thananyone would ever need, and would have in itself cost as much as a completePC at the time the chip was introduced.

Sixteen bits can be stored in two bytes, and can be manipulated readily in the8086’s 16-bit registers. Therefore the 8086 handles addresses internally as 16-bit values. While programmers need to know the precise function of each ofthese registers, it isn’t essential knowledge for support and maintenancepeople. However, it is useful to be able to understand the addressing notationused, since the configuration instructions for many add-on cards may refer tomemory addresses using this notation.

GENERAL TYPES OF MEMORYThe random access memory most commonly used in PCs and compatibles,and in almost all modern computers, is Dynamic RAM (DRAM). Refer fig. 7.4.This is because DRAM is the cheapest types of memory, consumes the leastpower, and has the greatest capacity per chip. If you were asked to design amemory chip, you’d probably make it so that, once the binary pattern of 0s

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and 1s that represented your data was stored, it would beretained for as long as power was applied to the chip.Memory which is made like this is called Static RAM (SRAM).It is very fast, but requires several transistors for each bit,so the chips are relatively large for their capacity, consumemore power and are expensive.

Dynamic RAM uses a simpler design in which each bitneeds just a single transistor. Data is stored in capacitors.After reaching the peak value capacitor discharges andthen recharges. This is called refreshing hence each bit isperiodically refreshed to retain the correct value. This andother factors, mean that DRAM is not as fast SRAM. However,DRAM lends itself to the incorporation of massive numbersof memory cells on a single chip. Another type of memoryyou will encounter is ROM, this type of chip has programinstructions built into it during manufacture, so that they arenot lost when power is removed. It is never possible tooverwrite these instructions they may only be read.

ROM chips are used to hold program instructions that area permanent part of the computers design, such as the

Basic Input Output System (BIOS) code. We will look at the BIOS later.

Dynamic RAM is used for main memory in PC because of its high capacityand low cost. However, it has one disadvantage: It’s slow. A period has to beallowed after each access for the memory cells to recharge, before they canbe accessed again. This restricts the speed at which the processor can transferinformation to and from memory.

Memory chips are rated by their manufacturers in terms of their access time.For a read access, this is the length of time it takes for the data to appear onthe data bus, after the address has been specified on the address bus. Theaccess time is measured in nanoseconds (ns). For a particular memory chip,it can be determined from a number that appears as a suffix to the part numberprinted on the chip. This gives the access time in units of 10 nanoseconds. Toslow the processor down to the speed of the memory, a wait state must beinserted, that is, an extra processor cycle during which the CPU does nothingbut wait for data it has requested. Wait states waste time- and hence power-so they should be avoided. That’s why faster machines need faster memoryand even use techniques like caching memory in SRAM, to keep the processorwaiting as little as possible.

MEMORYTYPE

DRAM

SRAM

ROM

PROM

EPROM

EEPROM


Fig. 7.4 Types of RAM &ROM.

Some applications

DYNAMIC RAMMain primary storage device formainframes, minicomputers, andpersonal computersSTATIC RAMMicrocomputers requiring a smallstorage capacity; high speedversions minicomputer bufferstorage; low power versions forportable computers.READ ONLY MEMORYProgramme storage for personalcomputers; character set storagefor visual displays and printers.PROGRAMMABLE ROMMicroprogram control instructionsfor minicomputers; military andautomobile uses.ERASABLE PROMSame as for ROM. Ability toreprogram makes it easier tocorrect errors during softwaredevelopment.ROM and EPROM applicationsneeding occasional program or datamodifications.

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CONTROL BUSES

System bus is the PC's main transportation system, that connects its maincomponents - CPU, Memory, Control logic and Input-Output (I/O ports). Likeits road-going name-sake, the bus is simply the means of conveying something- in this case digital information - from one place to another. Fig. 7.5, showsa simplified block diagram of a PC. The system bus can be view as threedistinct parts: The address bus, the data bus and the control bus, which conveyaddress, data and control signals between the CPU, memory and otherdevices.The most common type of memory access is to transfer data to and from theCPU. The microprocessor obtain a byte of data from memory as follows. First,the address of the memory location required is placed on the address bus anda signal is then sent on the MEMR line of the control bus. This tells the hardwareto copy the contents of that memory location onto the data bus so that it canread into one of the processors registers. Refer fig. 7.5.

A byte is written to memory in a similar way. The address is placed on theaddress bus and the byte of data is placed on the data bus. A MEMW signalis sent, and the hardware then stores the data value in the memory locationspecified, overwriting the previous contents. Each read or write is known as amemory cycle.

I/O ports are a little like memory addresses. However they can be read fromor written to not only by the CPU, but also by devices which interface with theoutside world. They are used to communicate with things like the keyboard,or the serial port. I/O ports aren’t just used to get data into or out of the system,though, they are also used to set up and control parts of the hardware, andget information about its status.

For example a serial port has one I/O address which is used to read and writedata, and another that is used to set up the speed, word length, parity andother characteristics. Others are used to obtain information about things likewhether there is a device on the other end of the cable, or whether a characterhas been received. Normally, this is all taken care of by the low level software-

Fig. 7.5 Microcomputerarchitecture showingdifferent buses.


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I/O PORT ASSIGNMENTS

Port Deviceaddressrange

000h-01Fh DMA Controller 1020h-03Fh Interrupt Controller 1040h-05Fh Timer060h-06Fh Keyboard Controller070h-07Fh CMOS Real-time Clock (AT)080h-09Fh DMA Page Registers (AT)0A0h-0BFh Interrupt Controller 2 (AT)0C0h-0BFh DMA Controller 2 (AT)0E0h-0EFh Real-time Clock (PS/2 Model 30)0F0h-0FFh Math Co-processor1F0h-1F8h Hard-disk Controller (AT)200h-20Fh Game Port210h-217h Expansion Box (PC,XT)270h-27Fh Parallel Port 2 (PC, XT), 3 (AT)2B0h-2DFh EGA Adaptor (Alternate)2E8h-2EFh Serial Port 42F8h-2FFh Serial Port 2320h-32Fh Hard disk Controller (XT)360h-36Fh PC Network378h-37Fh Parallel Port 1 (PC,XT), 2 (AT)3B0h-3BFh Monochrome Adaptor/Parallel Port3BCh-3BFh Parallel Port 1 (AT)3C0h-3CFh EGA Adaptor3D0h-3DFh CGA, EGA, VGA Adaptor3E8h-3EFh Serial Port 33F0h-3F7h Diskette Driver Controller3F8h-3FFh Serial Port 1

Fig. 7.6 I/O Port Assignments.

such as that contained in the system BIOS-which handles theserial port. All the user has to do is to read from or write to thedevice.

I/O ports are read from and written to in much the same asmemory. For output, the address is placed on the address bus,and then the byte of data to be written is placed on the databus the microprocessor then sets the IOW status line to show thatit is writing to an I/O port rather than a memory location. Asimilar process is followed for Input.

A common support problem occurs when two expansion cardsin a PC are configured to use the same I/O port addresses.Usually the result is that neither expansion card works. Thestandard devices like serial ports and disk controllers havestandard I/O addresses reserved for them. Refer fig. 7.6.However, devices like tapes, streamers and SCSI adapters werenot envisaged when the PC was designed. If the system has oneof these devices then you must set it up to use addresses whichare not reserved or are reserved for another device not present.

Memory is basically an array of 8 bit wide location each ofwhich can be uniquely addressed. The 8086 and 8088microprocessors used in the basic PC can address upto 1Mb ofmemory. 20 bits are needed to represent a million uniqueaddresses, so these computers have an address bus 20 bitswide. The control bus is a collection of signals, each of whichis a message from one part of the hardware to another. One

example as we’ve already seen is the way the microprocessor tells the memorywhether it wants to read from or write to the location specified on the addressbus. Two signal lines are used. One, called MEMR, is used when the processorwants to read from memory. When it wishes to write to memory it uses the signalMEMW. Other signals on the control bus include, interrupt request (IRQs) -signals to the microprocessor from external devices - and the system clock.

INTERRUPTSInterrupt requests (IRQs) are signals generated by devices on the bus to requestservice. An example would be the serial port that has received a character froman attached input device. The serial port has no buffering so can receive onlyone character at a time. The processor must read the character, and place itin a buffer in memory, otherwise it will be overwritten by the next on to bereceived. As in this example, interrupts need to be dealt with quickly, or datais lost.

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In the PC architecture, interrupts are handled by a chip called the programmableinterrupt controller (PIC). This receives interrupt signals from devices, and issuesinterrupts to the CPU, dependent upon the priority that has been assigned toeach device. When the CPU receives an interrupt, it responds by savinginformation about what it is currently doing, and jumping to a special interruptservice routine (ISR). Each device has its own ISR. This may be provided by theBIOS, as in the case of the keyboard or by an application such as a tapebackup program, which would provide its own routine to service the tapestreamer. After the ISR has been completed, the CPU uses the saved informationto resume what it was doing before the interrupt occurred.

An interrupt request from one device can be received while an ISR for anotheris being processed. If this occurs, the PIC holds on to it until the CPU informsit that the earlier interrupt has been dealt with. The interrupt controller wasprogrammed at start-up with priorities for the different interrupt requests, whichaffects the order in which it deals with them. If a program incorrectly modifiesthese priorities, then it is likely that the system will malfunction.

The INTEL 80x86 series CPUs can deal with up to 256 different interrupt types,numbered from 0 to 255. The start addresses for each ISR - called interruptvectors, and each occupying four bytes - are stored in the first 1024 bytes ofsystem memory.

The circuitry of a microprocessor is very complex. It contains millions ofindividual transistors, each of which has a specific function to perform. Theclock is needed, essentially, to beat time and ensure the microprocessor, thememory and other parts of the computers logic work together harmoniously.Each doing its job at the appropriate moment. The performance of thecomputer is related to the speed of the clock. The clock speeds are measuredin millions of cycles (or ticks) per second. The unit of cycles per second is thehertz (Hz); a million cycles per second is one Megahertz (MHz).

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LAB EXERCISE 7.1 : Identification of Backpanel Connectors

Objective: To be familiar with the different components of the PC and thedifferent connectors on the backpanel of the PC.

Tasks:

1. Identify the different external components such as monitor, keyboard, mouse,CD-Rom, Floppy Drive and the additional bays provided and for whatpurpose?

2. Identify the connector which is used by the keyboard to connect to themotherboard and what is called?

3. Identify the connector which is used by the modem to connect to themotherboard and what is called?

4. Identify the connector which is used by the printer to connect to themotherboard and what is called?

5. Identify the socket for USB devices?

6. Identify the socket for mike on the backpanel of the cabinet?

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A personal computer is not capable doing anything without an OS. There aresome terms such as Bootstrapping, BIOS and Post which play a part insuccessful running of an OS.

Let us get familiar with these terms.

Bootstrapping: When a PC is turned on, nothing seems to happen for severalseconds. This is the time when your computer is going through a complex setof operations to make sure that all of its components are working. Bootstrapis a small amount of code which lets the PC do something entirely on its own.It actually brings all its components to life so that they can accomplish the goalof loading on OS. In other words it performs two major functions ie. POST andSearching drives for an OS (in HDD, FDD). When these functions are complete,the boot operation launches the process of reading the OS's files and loadingthem into RAM.

The second term involved is BIOS

BIOS: Every Motherboard carries a BIOS (Basic Input Output System) that existson ROM chip. This chip is programmed with Software that controls the flowof information among the various components of the computer and it alsohandles information regarding the various hardware present in the system. Therecent advancements made in BIOS are the Advanced Power Management,Plug and Play support and Automatic Processor Speed detection. At presentthere are jumperless motherboards, where all parameters ranging from theprocessor's core voltage to the configuration and control of integratedperipherals can all be automatically detected and configured. Features likeWake on Lan allows the computer to be remotely powered on, enablingunsupervised uploading of data on a computer system in a LAN environment.Likewise another feature called Wake on Modem ring allow the computer toautomatically power itself on for receiving information over telephone lineslike faxes using the necessary software.

POST: (Power on Self Test) is the first thing your PC does when you turn it on.There are some testing routings that are stored in your ROM BIOS which bring

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about the PC initialization. These routines are POST programs. Because mosttests are internal you may not be aware that POST is checking the Video board,Keyboard and memory all prior to booting the computer from a floppy diskor a hard disk. When the POST detects an error either from the Keyboard,display or memory or other various components it produces an error Warningin the form of a message or in form of beeps.

Booting Sequence:The system BIOS is what starts the computer running when you turn it on. Thefollowing are the steps that a typical boot sequence involves. Of course thiswill vary by the manufacturer of your hardware, BIOS, etc., and especially bywhat peripherals you have in the PC.

1. The internal power supply turns on and initializes. The power supply takessome time until it can generate reliable power for the rest of the computer,and having it turn on prematurely could potentially lead to damage.Therefore, the chipset will generate a reset signal to the processor (thesame as if you held the reset button down for a while on your case) untilit receives the Power Good signal from the power supply.

2. When the reset button is released, the processor will be ready to startexecuting. When the processor first starts up, it is suffering from amnesia;there is nothing at all in the memory to execute. Of course processormakers know this will happen, so they pre-program the processor toalways look at the same place in the system BIOS ROM for the start ofthe BIOS boot program. This is normally location FFFF0h, right at the endof the system memory (End of BIOS). They put it there so that the size ofthe ROM can be changed without creating compatibility problems. Sincethere are only 16 bytes left from there to the end of conventional memory,this location just contains a "jump" instruction telling the processor whereto go to find the real BIOS startup program.

3. The BIOS performs the power-on self test (POST). If there are any fatalerrors, the boot process stops.

4. The BIOS looks for the video card. In particular, it looks for the video card'sbuilt in BIOS program and runs it. This BIOS is normally found at locationC000h in memory. The system BIOS executes the video card BIOS, whichinitializes the video card. Most modern cards will display information onthe screen about the video card. (This is why on a modern PC you usuallysee something on the screen about the video card before you see themessages from the system BIOS itself).

5. The BIOS then looks for other devices' ROMs to see if any of them haveBIOSes. Normally, the IDE/ATA hard disk BIOS will be found at C8000h

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and executed. If any other device BIOSes are found, they are executedas well.

6. The BIOS displays its startup screen.

7. The BIOS does more tests on the system, including the memory count-uptest, which you see on the screen. The processor writes data to each chip,then reads it and compares what it reads with the data it sent to the chipsin the first place. A running account of the memory that's been checkedis displayed on the monitor during this test. The BIOS will generally displaya text error message on the screen if it encounters an error at this point.

8. The BIOS performs a "system inventory" of sorts, doing more tests todetermine what sort of hardware is in the system. Modern BIOSes havemany automatic settings and will determine memory timing (for example)based on what kind of memory it finds. Many BIOSes can also dynamicallyset hard drive parameters and access modes, and will determine theseat roughly this time. Some will display a message on the screen for eachdrive they detect and configure this way. The BIOS will also now searchfor and label logical devices (COM and LPT ports).

9. If the BIOS supports the Plug and Play standard, it will detect and configurePlug and Play devices at this time and display a message on the screenfor each one it finds.

10. The BIOS will display a summary screen about your system's configuration.Checking this page of data can be helpful in diagnosing setup problems,although it can be hard to see because sometimes it flashes on the screenvery quickly before scrolling off the top.

11. The BIOS begins the search for a drive to boot from. Most modern BIOSescontain a setting that controls if the system should first try to boot fromthe floppy disk (A:) or first try the hard disk (C:). Some BIOSes will evenlet you boot from your CD-ROM drive or other devices, depending onthe boot sequence BIOS setting.

12. Having identified its target boot drive, the BIOS looks for boot informationto start the operating system boot process. If it is searching a hard disk,it looks for a master boot record at cylinder 0, head 0, sector 1 (the firstsector on the disk); if it is searching a floppy disk, it looks at the sameaddress on the floppy disk for a volume boot sector.

13. If it finds what it is looking for, the BIOS starts the process of booting theoperating system, using the information in the boot sector. At this point,the code in the boot sector takes over from the BIOS. If the first devicethat the system tries (floppy, hard disk, etc.) is not found, the BIOS will thentry the next device in the boot sequence, and continue until it finds abootable device.

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14. If no boot device at all can be found, the system will normally displayan error message and then freeze up the system. What the error messageis depends entirely on the BIOS, and can be anything from the rather clear"No boot device available" to the very cryptic "NO ROM BASIC - SYSTEMHALTED".

This process is called a "cold boot" (since the machine was off, or cold, whenit started). A "warm boot" is the same thing except it occurs when the machineis rebooted using {Ctrl}+{Alt}+{Delete} or similar in which case the POSTis skipped and the boot process continues roughly at step 8 above.

Booting to DOSThe following booting steps are explained with reference to MSDOS O.S.(Operating System).

• After the Post, the boot program contained on the Computer's ROM BIOSchips checks the floppy drive to see if it contains a formatted floppy disk.If the disk is mounted in drive the program searches specific locations onthe disk for the system files of an 0.S. The system files which are hiddenin MS DOS systems are named IO.SYS, MSDOS.SYS. If floppy drive isempty, boot program checks the hard drive C for the system files. If bootdisk does not contain the files, the boot program generates an errormessage.

• After System files have been located, the boot program reads the datastored on the disk's first sector and copies that data to specific locationsin RAM. This formation constitutes the DOS boot record. The boot recordis only about 512 bytes. After the BIOS boot program has loaded the bootrecord into memory, the BIOS passes control to the boot record bybranching to that address.

• Boot Record then takes control of the PC and loads IO.SYS into RAM. TheIO.SYS file contains extensions to the ROM BIOS and includes a routinecalled SYSINIT that manages the rest of the boot up. After loading IO.SYS,the boot record is no longer needed and is replaced in RAM by other code.

• SYS INIT assumes control of the start up process and loads MS DOS.SYSinto RAM. The MSDOS.SYS file works with the BIOS to manage files, executeprograms and respond to signals from hardware.

• Under DOS, SYSINIT searches the root directory of the boot disk for a filenamed CONFIG.SYS. If CONFIG.SYS exists, SYSINST tells MSDOS.SYS toexecute the commands in the file CONFIG.SYS created by the user.

The commands in CONFIG.SYS instruct the OS to handle certain operationssuch as how many files may be opened at one time. CONFIG.SYS also containinstructions to load device drivers. Device drivers are files containing code that

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extends the capabilities of the BIOS to control memory or hardware devices.

• SYSINIT tells MS DOS.SYS to load the file command.com which is dividedinto following separate parts in memory.

• Resident portion : Resides in memory immediately after MSDOS.SYSand its data area. This portion contains the routines to process interruptsof critical error handling, control break handling and terminatingaddresses.

This includes displaying error messages and interpreting the replyAbort, Retry or Ignore. All error handling is done over here.

• Transient portion : It contains internal DOS commands such as DIR,COPY etc. It is loaded at the high end of conventional RAM where itcan be overwritten by application programs if they need the memory.

• Initialization Portion : Is used only once and then discarded. This partsearches the root directory for a file named Autoexec.bat. This file iscreated by the computer's user and contains a series of DOS batch filecommands and names of programs that the user wants to run each timethe computer is turned on.

• Once the command.com is loaded, PC is now fully booted and ready tobe used.

BIOS Startup ScreenWhen the system BIOS starts up, you will see its familiar screen display,normally after the video adapter displays its information. These are thecontents of a typical BIOS start up screen.

• The BIOS Manufacturer and Version Number.

• The BIOS Date: The date of the BIOS can be important in helping youdetermine its capabilities, since the "magic dates" of some features arefairly well known.

• Setup Program Key: The key or keys to press to enter the BIOS setupprogram. (This is usually {Del}, sometimes {F2}, and sometimes anotherkey combination.

• System Logo: The logo of the BIOS company, or in some cases the PCmaker or motherboard manufacturer.

• The "Energy Star" Logo: This distinctive logo is displayed if the BIOSsupports the Energy Star standard, which almost all newer ones do.

• The BIOS Serial Number: This is normally located at the bottom of thescreen. Since BIOSes are highly customized to the particular motherboard,this serial number can be used in many cases to determine the specificmotherboard and BIOS version you are using.

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.

Serial, Parallel, PS/2, SCSI USB Interface

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The various ports on the computer allow it to communicate with the manydifferent devices and peripherals attached. The connectors on the back of yourcomputer may also be called as input/output ports (i/o ports) or communicationports. (Refer fig. 9.1)

The first thing to know is the difference between a male and female connector.The male connector fits inside the female connector. If the connector has pins

protruding from it, its a male connector. If theconnector has holes for the pins to fit into,then its a female connector. When you hooksomething up to your computer, the male andfemale connectors are hooked together.

The second thing you should remember isthat when you join a connector to a port, theymust have the same shape and the same

number of pins or holes.

The various I/O ports are Serial, Parallel, PS/2, USB & Firewire ports. Out ofthe I/O ports mentioned except the USB & Firewire port, the other ports arenot hot swappable.

USB and Firewire ports are the only ports that should be considered hot-swappable (this means they can be plugged in or unplugged while the machineis on).

External ports (which are linked to the motherboard) allow users to connectdevices such as scanners, printers, mice and keyboards.• Serial: A serial port can be used to connect many types of devices. Data

is transferred to and from the device one bit at a time.• Parallel: A parallel port usually has a 25-pin connector and is most often

used to connect local printers. Devices attached to a parallel port arecapable of receiving more than one bit of data at a time.

• PS/2: PS/2 ports are used to connect the mouse and the keyboard.

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Serial, Parallel, PS/2,SCSI & USB Interface

1

2

3

4

5

6

Fig. 9.1 Different ports in aPC


1. USB port connectors2. PS/2 mouse port connector3. PS/2 keyboard port controller

4. parallel port controller5. serial port connector (COM1)6. serial port connector (COM2)


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Serial and parallel ports are currently considered to be "legacy ports," sincethey use old technology for data transfer. Newer technology includes thefollowing:• USB 1.1 - USB Basic Speed

USB (Universal Serial Bus) is an external bus standard that supports datatransfer rates of 12 Mbps (12 million bits per second). A single USB portcan be used to connect up to 127 peripheral devices, such as mice,modems, and keyboards. USB also supports Plug and Play installation and"hot plugging," meaning you do not have to shut down the computer inorder to attach or detach a device from the machine.

• USB 2.0 - USB Hi-SpeedUSB 2.0 is a new version of the USB specification. This new port isbackwards-compatible, allowing older USB 1.1 devices to connect andoperate without trouble. However, the new USB Hi-Speed ports supportdata transfer rates of 480 Mbps, even faster than FireWire ports.

FireWireFireWire is a very fast external bus standard that supports data transfer ratesof up to 400 Mbps (400 million bits per second). The name FireWire hasactually been trademarked by Apple; FireWire is also known as IEEE 1394.(IEEE stands for the Institute of Electrical and Electronics Engineers.) A single1394 port can be used to connect up to 63 external devices and is much fasterthan USB 1.1. It supports both Plug and Play and hot plugging and alsoprovides power to peripheral devices.

When IBM designed the PC, they wanted to simplify the installation,programming, and operation of devices. Because virtually every peripheralneeds both an IRQ and I/O address, IBM created standard preset combinationof IRQs and I/O addresses. For serial devices, the preset combinations arecalled COM ports. For parallel devices, they are called LPT ports. The word"port" is used to describe a "portal" or two-way access. Following table lists thepreset combinations of I/O addresses and IRQs.

COM and LPT Assignments

Port I/O Address IRQCOM 1 3F8 4COM2 2F8 3LPT1 378 7LPT2 278 5

Ports do make installation easier. Consider modems; many do not have asetting for IRQs or I/O addresses. Instead, you set their COM port. When oneselects a COM port, they actually assign the IRQ and I/O address. If you set


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a modem to COM1, that means you are setting modem's IRQ to 4 and themodem's I/O address to 3F8.

ASYNCHRONOUS AND SYNCHRONOUS COMMUNICATIONThere are two schemes of transmitting data to the ports.• Asynchronous • Synchronous

In the asynchronous scheme, each character is transmitted with the start bit andthe stop bit as the synchronization bits.

In the synchronous scheme, a bit pattern called sync is transmitted after a fixednumber of data bytes.

Asynchronous communication is generally used with slow peripherals, whereasvery high speed transmission is possible with the synchronous communicationscheme.

SERIAL INTERFACE : PC supports two serial interfaces Each is an RS-232standard interface. The PC supports asynchronous and synchronouscommunication. Synchronous communication is rarely used, it is used only forhigh speed communications between PCs. Asynchronous is widely used in PCs.The serial interface takes care of converting the parallel data from the CPUinto serial data. It also adds the parity bits and start and stop bits to the datastream. The parity bit is used for error detection. The start and the stop bitsare used in achieving synchronization between sending end and the receivingend. In this method there can be time gaps between one byte and the next.When the data bits are received from the other end, the serial interfacecontroller converts them into parallel data bytes. It also removes the start-stopbits and check for parity error. It can be operated both in interrupt mode andin the program mode for data transfer. The two serial interfaces are referredto as COM1 and COM2.

THE RS232 SERIAL INTERFACE : The RS-232 interface is a standardinterface specified by the Electronic Industries Association (EIA) and is followedby the manufacturers of computers and data communications products (RSstands for Recommended Standard). The RS-232C is the latest version of theRS-232 interface. RS-232 was basically designed to allow computing devicescalled data terminal equipment (DTE) to talk to communications devices calleddata circuit-terminatting equipment (DCE). So there's a DTE-type RS-232interface and a DCE-type RS-232 interface. RS-232 is designed to allow DTEsto talk only to DCEs. RS-232 uses DB25 and DB9 connectors. Male connectorsgo on the DTEs; female connectors go on the DCEs.

DTE-type interfaces are most commonly found on PCs. Devices with DCE withDCE-type interfaces include modems, mice, and scanners.


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The RS-232 interface expects a Modem to be connected to both the receivingand the transmitting end.

The DTE and the DCE are linked via a cable whose length should not exceed

50 ft. In practice the manufacturers extend this length to 100 ft. or more. The

DTE has a 25 pin D type male connector and the DCE has 25-pin D-type

female connector. However some of the manufacturers use 9-pin connectors.

SIGNAL LEVELS : The RS-232 standard follows a negative logic. A logical 1

is represented by a negative voltage and a logical 0 is represented by a

positive voltage. The level 1 (High) varies from -3 to -15V and the level 0 (low)

varies from +3 to +15V. In practice the hardware circuits used for the RS-232

interface maintain the signal level at +12V (logical 0) and at -12V (logical1).

Parallel (Centronics) Interfaces/IEEE 1284The most common method of attaching a printer to a computer is through asimple interface called the Centronics interface. The interface was named afterCentronics, the company that invented it in 1976. It's more commonly knowntoday as the parallel port.

The IBM PC's parallel port was originally a proprietary interface, but it'sbecome so widely used that there is now an "official" standard describing it,IEEE 1284.

The original PC's parallel port had eight outputs, five inputs, and fourbidirectional lines. A parallel port transfers multiple bits at once, while a serialport transfers a bit at a time. These are enough for communi-cating with manytypes of peripherals.

On many newer PCs, the eight outputs can also serve as inputs, for fastercommunications with scanners, drives, and other devices that send data to PC.

The parallel port was designed as a printer port, but these days, one can findall kinds of things besides printers connected to the port.

PCs can support up to three parallel ports. They are named LPT1, LPT2, andLPT3; the name refers to Line Printer 1, 2 or 3.

CENTRONICS INTERFACE: The CENTRONICS INTERFACE provides a

handshake protocol between a computer and a printer and supports a

maximum data transfer speed of about 100 Kb/s. The printer side of the

interface is a 36 pin connector and the PC side is a 25 pin D type connector.

The PC uses 36 pin flat cable in which every alternative wire is for the ground.

Most of the signals should have twisted pair wiring in the cable. The signals

are TTL level signals and the twisted pair return ground wire for each signal

is connected to the signal ground level. To prevent noise effects the twisted pair


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wires are shielded and the shield is connected to the chassis ground in the

system box.

Port TypesAs the design of the PC evolved, several manufacturers introduced improvedversions of the parallel port. The new port types are compatible with theoriginal design, but add new abilities, mainly for increased speed.

The original parallel port was pretty fast enough for sending bytes representingASCII text characters to a dot-matrix or daisy-wheel printer. But modern printersneed to receive much more information to print a page with multiple fonts anddetailed graphics, often in color. The faster the computer can transmit theinformation, the faster the printer can begin processing and printing the result.

Here is a summary of the available types:

Original Standard Parallel Port (SPP)The parallel port in the original IBM PC, and any port that emulates the originalport's design, is sometimes called the SPP, for standard parallel port. The portin the original PC was based on an existing Centronics printer interface.

SPPs can transfer eight bits at once to a peripheral, using a protocol similarto that used by the original Centronics interface. The SPP doesn't have a byte-wide input port, but for PC-to-peripheral transfers, SPPs can use a Nibble modethat transfers each byte 4 bits at a time. Nibble mode is slow, but has becomepopular as a way to use the parallel port for input.

Enhanced Parallel Port (EPP)The EPP (enhanced parallel port) was originally developed by chip maker Intel,PC manufacturer Zenith, and Xircom, a maker of parallel-port networkingproducts.

An EPP can read or write a byte of data in one cycle of the ISA expansion bus,or about 1 microsecond, including handshaking, compared to four cycles foran SPP. An EPP can switch directions quickly, so it's very efficient when usedwith disk and tape drives and other devices that transfer data in both directions.

Enhanced Capabilities Port (ECP)The ECP (extended capabilities port) was first proposed by Hewlett Packardand Microsoft. Like the EPP, the ECP is bidirectional and can transfer data atISA-bus speeds. ECPs have buffers and support for DMA (direct memory access)transfers and data compression. ECP transfers are useful for printers, scanners,and other peripherals that transfer large blocks of data. An ECP can alsoemulate an SPP and many ECPs can emulate an EPP as well.


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Cables Compatible with Direct Cable Connection

We can use the Direct Cable Connection tool of Microsoft Windows to establisha direct serial or parallel cable connection between two computers. Windowssupports serial null-modem standard (RS-232) cables and the following parallelcables for use with Direct Cable Connection:

• Standard or basic 4-bit cables

• Enhanced Capabilities Port (ECP) cables

• Universal Cable Module (UCM) cables

Parallel cable connections are faster than serial cable connections. Use a serialcable with Direct Cable Connection only if a parallel port or cable isunavailable.

ECP cables work on computers with ECP-enabled parallel ports. ECP must be

enabled in both computers’ CMOS settings for parallel ports that support this

feature. ECP cables allow data to be transferred more quickly than standard

cables. Note that both computers must support ECP in order to use ECP cables.

UCM cables support connecting different types of parallel ports. Using UCMcable between two ECP-enabled ports allows the fastest possible data transferbetween two computers.

PS/2 portThis port was designed by IBM for their Personal System/2 computers. The PS/2 port has lived on in other computers as the standard for keyboards and mice.Most computers come with two PS/2 ports. This helps to free valuable serialports for modems and other serial devices.

This port is essentially a serial port but it uses different addresses and interruptsthan serial ports, so moving the mouse to a PS/2 port frees the serial port foruse. Not all mice are PS/2 compatible so even if you have a PS/2 mouse port,you might still have an expense for a new mouse. If you don't have a PS/2mouse port, you'll either need an adapter card that provides one or a newmotherboard that includes one.

The pin configuration for the PS/2 port is as shown the Fig. 9.6

Pin Description1 Mouse Data

2 Not Connected3 Ground

4 Power +5V5 Mouse Clock

6 Not Connected

PS/2 ports use synchronous serial signals to communicate between the keyboard


Fig. 9.6 PS/2 Port


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or mouse to the computer. The signals are all TTL logic level voltages (0 voltsfor logical 0 and +5 volts for logical 1). Bi-directional communications aresupported on all PS2 ports (mostly for keyboards but may be implementedin mouse only ports), all bi-directional transmissions are controlled by the clockand data lines. This feature is controlled by an open collector architecturewhich lets both lines to be forced to logical 0 by the device (mouse or keyboard)or the host computer. This means that at any point in time the host can forcethe clock line to 0 and inhibit the mouse to transmit. If the host inhibits whilethe mouse is transmitting the transmitted data must be retransmitted. Althoughthis may seem odd, both ports are usually controlled by an INTEL 8042keyboard controller (yes the keyboard controller also controls the PS/2 mouseport on it's second channel).

USB (Universal Serial Bus)USB is peripheral bus standard developed by PC and telecom industry leaders-Compaq, DEC, IBM, Intel, Microsoft, NEC and Northern Telecom-that bringsplug and play of computer peripherals outside the box, eliminating the needto install cards into dedicated computer slots and reconfigure the system.Personal computers equipped with USB allows computer periperals to beautomatically configured as soon as they are physically attached - without theneed to reboot or run setup. USB also allow multiple devices - up to 127 -to run simultaneously on a computer, with peripherals such as monitors andkeyboards acting as additional plug-in sites, or hubs.

This connection is simpler than a 9 pin serial port, since it has only four pins.USB is designed to be faster than serial ports. The standards 1.0 & 1.1described an interface that can transmit up to 5 Mb/s and 12 Mb/s respectivelyas opposed to the 100 + Kb/s of a serial interface. The speed is meant tokeep up with telephony applications, such as low resolution video conferencing.

The first shot in the arm the standard received was when Microsoft releasedMicrosoft's Windows 95 Service Release 2.1 patch, otherwise known as the USBSupplementary patch.

This patch, which updated yourversion of Windows to OSR 2.1,slowly became a requirementfor many Video cardinstallation processes amongother things, for no reasonother than to promote the USBstandard. While OSR 2.0 wasnecessary to enable full AGP

Fig. 9.7 USB Cable

USB Cable


VBusD-D+GND


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support under Windows 95, OSR 2.1 had nothing to do with the video supportat all, supporting the fact that the only reason OSR 2.1 was forced upon uswas to promote the USB standard. Even in spite of Microsoft's attempt tointegrate the standard into their Operating system, the USB did'nt make thatbig impression in the market. The primary reason for this being lack of USBperipherals.

The next step in the nudging process from the software end was, to completelyintegrate the USB support into the software which in this case happened to bethe Microsoft's newest Operating system : Windows 98, Windows ME, WindowsXP. These operating systems has full support for the Universal Serial Bus. Withthis evident, hardware manufacturers and most importantly, hardware vendorsbegan to announce and stock USB peripherals more readily. USB devices arereleased, since USB Cameras, Keyboards, and Mice have been available.

USB CableFor even simpler connectivity, the USB cable consists of only four wires: Vbus,D+, D-, and GND. A single standardized upstream connector type furtherincreases the ease-of use of USB peripherals. The data is differentially drivenover D+ and D- at a bit rate of 12 Mb/s for full-speed signalling, or a rateof 1.5 Mb/s for the USB low-speed signalling mode. The USB-compliant 8x930and 8x931 peripheral controller families have implemented the signallingtransceiver on-chip, eliminating the need for all external circuitry, except forthe pull-up terminating resistor on either the D+ or D- line to determine whetherthe device is full- or low-speed.

SCSI (Small Computer System Interface)BasicsSCSI (pronounced SKUH-zee and sometimescolloquially known as "scuzzy"), the SmallComputer System Interface, is a set of ANSIstandard electronic interfaces that allow personalcomputers to communicate with peripheralhardware such as disk drives, tape drives, CD-

ROM drives, printers, and scanners faster and more flexibly than previousinterfaces. Developed at Apple Computer and still used in the Macintosh, thepresent set of SCSIs are parallel interfaces. SCSI ports continue to be built intomany personal computers today and are supported by all major operatingsystems.



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In addition to faster data rates, SCSI is more flexible than earlier parallel datatransfer interfaces. The latest SCSI standard, Ultra-2 SCSI for a 16-bit bus cantransfer data at up to 80 megabytes per second (MBps).SCSI allows up to 7or 15 devices (depending on the bus width) to be connected to a single SCSIport in daisy-chain fashion. This allows one circuit board or card toaccommodate all the peripherals, rather than having a separate card for eachdevice, making it an ideal interface for use with portable and notebookcomputers. A single host adapter, in the form of a PC Card, can serve as aSCSI interface for a laptop, freeing up the parallel and serial ports for use withan external modem and printer while allowing other devices to be used inaddition.

Although not all devices support all levels of SCSI, the evolving SCSI standardsare generally backwards-compatible. That is, if you attach an older device toa newer computer with support for a later standard, the older device will workat the older and slower data rate.

The original SCSI, now known as SCSI-1, evolved into SCSI-2, known as "plainSCSI." as it became widely supported. SCSI-3 consists of a set of primarycommands and additional specialized command sets to meet the needs ofspecific device types. The collection of SCSI-3 command sets is used not onlyfor the SCSI-3 parallel interface but for additional parallel and serial protocols,including Fibre Channel, Serial Bus Protocol (used with the IEEE 1394 Firewirephysical protocol), and the Serial Storage Protocol (SSP).

A widely implemented SCSI standard is Ultra-2 (sometimes spelled "Ultra2")which uses a 40 MHz clock rate to get maximum data transfer rates up to 80MBps. It provides a longer possible cabling distance (up to 12 meters) by usinglow voltage differential (LVD) signaling. Earlier forms of SCSIs use a single wirethat ends in a terminator with a ground. Ultra-2 SCSI sends the signal overtwo wires with the data represented as the difference in voltage between thetwo wires. This allows support for longer cables. A low voltage differentialreduces power requirements and manufacturing costs.

The latest SCSI standard is Ultra-3 (sometimes spelled "Ultra3")which increasesthe maximum burst rate from 80 Mbps to 160 Mbps by being able to operateat the full clock rate rather than the half-clock rate of Ultra-2. The standardis also sometimes referred to as Ultra160/m. New disk drives supportingUltra160/m will offer much faster data transfer rates. Ultra160/m also includescyclical redundancy checking (CRC) for ensuring the integrity of transferreddata and domain validation for testing the SCSI network.

Currently existing SCSI standards are summarized in the table below.


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Max. Max. Max.Technology Name Cable Speed Number of

(meters) (MBps) Devices

SCSI-1 6 5 8

SCSI-2 6 5-10 8 or 16

Fast SCSI-2 3 10-20 8

Wide SCSI-2 3 20 16

Fast Wide SCSI-2 3 20 16

Ultra SCSI-3, 8-bit 1.5 20 8

Ultra SCSI-3, 16-bit 1.5 40 16

Ultra-2 SCSI 12 40 8

Wide Ultra-2 SCSI 12 80 16

Ultra-3 (Ultra160/m) SCSI 12 160 16

LAB EXERCISE 9.1 : Serial and Parallel Port

Objective: To be familiar with the different ports which are present onthe PC

Tasks:1. What are the port addresses and IRQ's settings for serial and parallel

ports?Observation: Port Address Interface

Serial COM1COM2COM3COM4

Parallel LPT1LPT2

2. Identify different type of SCSI Interfaces their speed, distance covered and nodevices it can support?

MemoryCMS COMPUTER INSTITUTE

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Memory

CMS COMPUTER

INSTITUTE

10PC ENGINEERING

Memory as shown in the fig. 10.1 is classified primarily into two parts i.e.primary storage and secondary storage .

Primary Storage is further classified into two types i.e. ROM and RAM.

Secondary storage contains the different devices as mentioned in the fig. 10.1the Floppy disk, Hard disk, Zip disk and DAT cartridge.

Memory is that part of your computer that is used to store information. Memorychips are integrated circuit made of various components (transistors, resistorsand capacitors) formed on the same chip. The leading companies which arethe memory supplies are Micron, Siemens etc.

Memory is referred to as primary storage device ie, the contents of storagesystem are in a form that your PC's Microprocessor can immediately access,and are ready to be used. In fact, some direct instructions used by Microprocessorcan alter the values held in primary storage without the need to transfer thedata into the chip's registers. For this reason primary storage is referred to asworking memory.


Fig. 10.1 Types of Storage

MEMORY

FLOPPY HARD ZIP DATDISK DISK DISK CARTRIDGE

PRIMARYSTORAGE

SECONDARYSTORAGE

ROM RAM

PROM EPROM EEPROM SRAM DRAM

FPM EDO SDRAM ECC DDR SGRAM VRAM RDRAMDRAM SDRAM


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Now going to the primary storage devices types available are.

ROM (Read Only Memory)ROM is where data is stored permanently. Hence it is also called as NonVolatile Memory. This means data is hard-wired into the ROM chip.

The way a ROM chip works necessitates the programming of complete datawhen the chip is created. You cannot reprogram or rewrite a standard ROMchip. If it is incorrect, or the data needs to be updated then you have to throwit away and start over again. They use very little power, are extremely reliableand, in the case of most small electronic devices, contain all the necessaryprogramming to control the device.

Hence BIOS is stored on ROM because the user cannot disrupt the information.There are different types of ROM as mentioned below.

PROM (Programmable Read only Memory).This is basically a blank ROM chip that can be written to, but only once.

They are more fragile than ROMs. A jolt of static electricity can easily causefuses in the PROM to burn out, changing essential bits from 1 to 0.

It is much like a CD-R drive that burns the data into the CD.

EPROM (Erasable Programmable Read only Memory).This is just like PROM, except that you can erase the ROM by shining a specialultra-violet light into a sensor on top of the ROM chip for a certain amountof time. Doing this wipes the data out, allowing it to be rewritten.

The ultra-violet light used is at a particular frequency that will not penetratemost plastics or glasses, and thus at each EPROM chip has a quartz windowon top of it. An EPROM eraser is not selective, it will erase the entire EPROM.

EEPROM (Electrically Erasable Programmable Read Only Memory).

EEPROM chips remove the drawbacks of EPROMs.

In EEPROMs:

• The chip does not have to removed to be rewritten.

• The entire chip does not have to be completely erased to change a specificportion of it.

• Changing the contents does not require additional dedicated equipment.Instead of using UV light, you can return the electrons in the cells of anEEPROM to normal with the localized application of an electric field to eachcell. This erases the targeted cells of the EEPROM, which can then berewritten. Any byte within an EEPROM may be erased and rewritten.


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Flash MemoryFlash memory is actually a variation of electrically erasable programmableread-only memory (EEPROM). EEPROM chips are too slow to use in manyproducts that make quick changes to the data stored on the chip. Flashmemory devices are high density, low cost, nonvolatile, fast (to read, but notto write), and electrically reprogrammable. These advantages are overwhelmingand, as a direct result, the use of flash memory has increased dramaticallyin embedded systems. From a software viewpoint, flash and EEPROMtechnologies are very similar.

The big difference between the two is that EEPROM can be erased and rewrittenat the byte level; flash memory can erase or reprogram blocks of bytes, notindividual bytes, hence it is faster. There are several different types of storagemedia that utilize flash memory technology. Most of these flash memorydevices connect to your computer add-on card reader. One can also accessthe data on a card by connecting the host digital device to the PC. Some e.g.'sof flash memory devices are BIOS chip, SmartMedia, Memory stick, Flash USBDrive etc.

The next primary storage device is the RAM (Random Access Memory)

RAM (Random Access Memory)RAM is the best known form of computer memory. RAM is considered "randomaccess" because one can access any memory cell, which is the basic unit ofdata storage, in the same amount of time. The opposite of RAM is serial accessmemory (SAM). SAM stores data as a series of memory cells that can only beaccessed sequentially. If the data is not in the current location, each memorycell is checked until the needed data is found. SAM works very well for memorybuffers, where the data is normally stored in the order in which it will be used.RAM data, on the other hand, can be accessed in any order.

RAM is a volatile memory, meaning all data is lost when power is turned off.RAM is used for temporary storage of program data, allowing performanceto be optimum. It is this region into which programs are loaded before theCPU processes the information.

RAM BasicsIn the most common form of computer memory, dynamic random accessmemory (DRAM), a transistor and a capacitor are paired to create a memorycell, which represents a single bit of data. The capacitor holds the bit ofinformation - a 0 or a 1. The transistor acts as a switch that lets the controlcircuitry on the memory chip read the capacitor or change its state.

Capacitors have two non conducting plates. When an electric voltage differenceis applied between the two plates, a charge gets stored within this components.


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This charge remains on it, so long as there is an electric potentialapplied between plates. Otherwise it gets discharged over a periodof time. To counter this problem, the charge on the capacitors usedin RAM is constantly refreshed so as to keep the information withinit and hence the name Dynamic RAM.

Writing Operation

• The initial phase of writing data to a particular cell in RAMconsists of first activating the address line that is connected to cellthrough an electrical pulse. It is this line that identifies the cell in which

the unit of information is stored. The transistor within it is used as electronicswitch.

• When the transistor is turned on, the operating system sends bursts ofsignals along the consecutive data line that represent 0 or one which isfound in cells sequentially, hence writing data into RAM is faster as the sameaddress line is already activated for that particular row of cell.

• When an electrical pulse from the data reaches a transistor that is activatedby an address line, the transistor switches on and allows current to passthrough, thus charging the capacitor connected to it. Since capacitor hasthe tendency of discharging it has to be refreshed. This is done by applyingstrobes of charges on the data line so as to keep charge on the capacitor.

It is the capacitor which stores information or data.

RAM memory is classified in the following ways:• Package type, which refers to the plastic coating containing theactual silicon. With today's memory modules, the package type is aterm rarely used, but in case you are working on a very old system,packaging for RAM can be any of the following.

• Dual Inline Package (DIP) is the original memorychip used back in the days when individual memory chips were insertedin sockets on the motherboard. They are little, black, plastic bricks withtwo rows of metal legs, one on each of their long sides, hence the namedual inline.

• ZIP (Zigzag Inline Package) briefly replaced DIP; all of the connectorswere on one side, allowing the memory package to rest on its siderather than lying flat so that it took up less room on the motherboard.The Zip package departed with the appearance of memory modules.

• Form factor, which refers to the module that contains one or more of thefollowing packages:

• Single Inline Pin Package (SIPP) was the first attempt at a memory

Fig. 10.2 Diagram of 1-BitDRAM Storage Cell.



Fig. 10.3 DIP Memory chip


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module. The SIPP is a small circuit boardcontaining several memory chips and hasa single row of pins across the bottom.You will find SIPP memory on olderpersonal computers and workstations. TheSIPP memory resembles SIMMs exceptthat it has tiny pins instead of an edgeconnector. SIMMs eventually replaced

SIPPs because the SIPP pins tended to bend or break easily.

• Single Inline Memory Module(SIMM) is a modular circuit board withmemory chips soldered on it. The SIMMhas an edge connector that allows theentire SIMM module to be inserted into asocket on the motherboard. The earlySIMMs had 30 pins and were 3.5 inches inlength; the 72-pin SIMMs that later replacedthem were 0.75 inches longer.

• Double Inline Memory Module(DIMM) looks almost identical to the SIMM; however, the SIMM hasmemory chips on one side while the DIMM has memory mounted onboth sides. To accommodate the extra memory, the DIMM has connectorson both sides of the module, giving it 168 pins. Another differencebetween the SIMM and the DIMM is the way that the modules areinstalled. The 72-pin SIMM installs at a slight angle, whereas the 168-pin DIMM installs straight down into the memory socket on themotherboard.

• Small Outline DIMM (SO-DIMM) is the module that is now incommon use in notebook computers. It is much smaller than the 168-pin DIMM and is available in either 72 or 144-pin configurations.

• Rambus Inline memory Module (RIMM) is a 184-pin module thatlooks a little like a DIMM. RIMMs offer faster access and transfer speed,and thus generate more heat. An aluminium sheath, called a heatspreader, covers the module to protect the chips from overheating. TheRIMM is also available in a small outline form factor (SO-RIMM).

• PC Cards (also known as PCMCIA cards) , SmartMedia,CompactFlash, and memory sticks are small, thin modules that pluginto a special socket found mostly on notebook computers, digitalcameras, and Personal Digital Assistants (PDAs).

Fig. 10.4 SIPP Memorymodule chip


Fig. 10.5 Different types ofSIMM Chips

30 Pin SIMM

72 Pin SIMM


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• Access speed (how quickly the chip fetches data), which is measuredin nanoseconds. Common access times are 40-, 50-, 60-, 70-, and 80nsfor normal memories, and as low as 8ns for expensive, high-speedmemories. Lower numbers are faster.

• Memory capacity: modern DIMM/RIMM capacity ranges from 32MB to1024 MB for memory modules.

Different Types of RAMRAM's are also classified according to their working . There are many differenttypes of RAMs, which include the many flavors of Dynamic RAM (DRAM) andStatic RAM (SRAM).

Dynamic RAM (DRAM)Dynamic RAM is a type of RAM that only holds its data if it is continuouslyaccessed by special logic called a refresh circuit. Many hundreds of times eachsecond, this circuitry reads the contents of each memory cell, whether thememory cell is being used at that time by the computer or not. Due to the wayin which the cells are constructed, the reading action itself refreshes the contentsof the memory. If this is not done regularly, then the DRAM will lose its contents,even if it continues to have power supplied to it. This refreshing action is whythe memory is called dynamic.

The reason that DRAMs are used is simple: they are much cheaper and takeup much less space. The overhead of the refresh circuit istolerated in order to allow the use of large amounts ofinexpensive, compact memory.

DRAMs are smaller and less expensive. DRAMs are madeusing only one transistor and a capacitor. The capacitor,when energized, holds an electrical charge if the bit containsa "1" or no charge if it contains a "0". The transistor is usedto read the contents of the capacitor. The problem withcapacitors is that they only hold a charge for a short periodof time, and then it fades away. These capacitors are tiny,so their charges fade particularly quickly. This is why therefresh circuitry is needed: to read the contents of every celland refresh them with a fresh "charge" before the contentsfade away and are lost.

The different types of DRAM which are used are as follows:

FPM (Fast Page Mode) RAMA type of RAM that allows faster access if the data beingcalled is in the same row as the data previously requested.


Types of RAM

Fig. 10.6 Types of RAM

SDRAM

DDR SDRAM

RDRAM


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Also called page mode memory. These were the first memory chips to use theburst mode timing, wherein data is read 32 bytes at a time one after the other.These are typical of processors from 8088/86 - 486.

EDO (Extended Data Out) RAM

EDO DRAM was nothing more than a moderate improvement on old-style FPMDRAM. EDO needed to be refreshed much less often, thereby providing anextended period where data could be taken out of RAM. EDO DRAM enableda system to access data more quickly than FPM RAM. EDO RAM was on eithera 72-pin SIMM or a DIMM (168 or SO), and looked exactly like regular DRAM.

To take advantage of EDO, one needed a chipset designed to handle EDO.The majority of the early Pentium systems used EDO RAM, but that was nottrue of the 486s with 72-pin SIMM slots. One had to refer to the motherboardbook to see if the system could use EDO RAM. EDO RAM enjoyed wideacceptance through most of the 1990s until the advent of a new, extremelypowerful type of DRAM called SDRAM. FPM and EDO RAM are now consideredobsolete.

SDRAM (Synchronous Dynamic RAM)SDRAM is still DRAM, but it is synchronous-tied to the system clock. Asmentioned earlier, regular DRAM (EDO or FPM) was not tied to any clock. Ifthe CPU wanted some data from RAM, the chipset sent the necessary signalsto the DRAM, waited a certain number of clock ticks, and then accessed theRAM again to get the data. The number of clicks of the clock was either setthrough CMOS or determined by the chipset every time the system booted up.The number of clicks was not exact, but rather rounded up to ensure that thechipset wouldn't access DRAM before the necessary data was ready. Thisrounding up wasted system time, but until recently DRAM was too slow to behandled any other way.

SDRAM is tied to the system clock, just like the CPU and chipset, so the chipsetknows when data is ready to be grabbed from SDRAM, resulting in little wastedtime. SDRAM is quite a bit faster than DRAM. SDRAM pipelines instructions fromthe chipset that enable commands to be ready as soon as the previous oneis taken by the chipset. Collectively, these improvements make SDRAM four tosix times faster than regular DRAM. SDRAM is available only on DIMMs whichhave 168 pin.

SDRAM ties to the system clock, it doesn't have an access speed; it has a clock

speed just like a CPU. Five clock speeds are commonly used 66, 75, 83, 100,and 133 MHz.


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DDR (Double Data Rate) SDRAMTypes of DDR MemoriesThere are presently three generations of DDR memories:

1. DDR1 memory, with a maximum rated clock of 400 MHz and a 64-bit (8bytes) data bus is now becoming obsolete and is not being produced inmassive quantities. Technology is adopting new ways to achieve fasterspeeds/data rates for RAM memories.

2. DDR2 technology is replacing DDR with data rates from 400 MHz to 800MHz and a data bus of 64 bits (8 bytes). Widely produced by RAMmanufacturers, DDR2 memory is physically incompatible with the previousgeneration of DDR memories.

3. DDR3 technology picks up where DDR2 left off (800 Mbps bandwidth) andbrings the speed up to 1.6 Gbps. One of the chips already announced byELPIDA contains up to 512 megabits of DDR3 SDRAM, with a columnaccess time of 8.75 ns (CL7 latency) and data transfer rate of 1.6 Gbpsat 1.6 GHz. The 1.5V DDR3 voltage level also saves some power comparedto DDR2 memory. What is more interesting is that at an even lower 1.36V,the DDR3 RAM runs fine at 1.333 GHz (DDR3-1333) with a CL6 latency(8.4 ns total CAS time), which matches the CAS time of the fastest currentDDR2 memory.

DDR2 versus DDR3The primary differences between the DDR2 and DDR3 modules are:

" DDR2 memories include 400 MHz, 533 MHz, 667 MHz and 800 MHzversions, while DDR3 memories include 800 MHz, 1066 MHz, 1333 MHzand 1600 MHz versions. Both types double the data rate for a given clockfrequency. Therefore, the listed clocks are nominal clocks, not real ones.To get the real clock divide the nominal clock by two. For example, DDR2-667 memory in fact works at 333 MHz.

" Besides the enhanced bandwidth, DDR3 also uses less power than DDR2by operating on 1.5V-a 16.3 percent reduction compared to DDR2 (1.8V).Both DDR2 and DDR3 memories have power saving features, such assmaller page sizes and an active power down mode. These powerconsumption advantages make DDR3 memory especially suitable fornotebook computers, servers and low power mobile applications.

" A newly introduced automatic calibration feature for the output data bufferenhances the ability to control the system timing budget during variationsin voltage and temperature. This feature helps enable robust, high-performance operation, one of the key benefits of the DDR3 architecture.


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SDRAM Devices Comparison

Items DDR3 SDRAM DDR2 SDRAM DDR SDRAM

Clock frequency 400/533/667/ 200/266/333/ 100/133/166/800 MHz 400 MHz 200 MHz

Transfer data rate 800/1066/1333/ 400/533/667/ 200/266/333/1600 Mbps 800 Mbps 400 Mbps

I/O width x4/x8/x16 x4/x8/x16 x4/x8/x16/x32

Prefetch bit width 8-bit 4-bit 2-bit

Clock input Differential clock Differential clock Differential clock

Burst length 8, 4 (Burst chop) 4, 8 2, 4, 8

Data strobe Differential Differential Single datadata strobe data strobe strobe

Supply voltage 1.5V 1.8V 2.5V

Interface SSTL_15 SSTL_18 SSTL_2

/CAS latency (CL) 5, 6, 7, 8, 9, 10 clock 3, 4, 5 clock 2, 2.5, 3 clock

On die termi-nation (ODT) Supported Supported Unsupported

Component FBGA FBGA TSOP(II) / FBGA /package LQFP

" DDR3 devices introduce an interrupt reset for system flexibility

In DDR2 memories, the CL parameter, which is the time the memory delaysdelivering requested data, can be three to five clock cycles, while on DDR3memories CL can be of five to ten clock cycles.

In DDR2 memories, depending on the chip, there is an additional latency(AL) of zero to five clock cycles. So in a DDR2 memory with CL4 the AL1latency is five.

DDR2 memories have a write latency equal to the read latency (CL + AL)minus one.

Internally, the controller in DDR2 memories works by preloading 4 databits from the storage area (a task known as prefetch) while the controllerinside DDR3 memories works by loading 8 bits in advance.

ECC (Error Correction Code) DRAM:Many higher-end systems use a special type of RAM called error correctioncode (ECC) DRAM, ECC is a major advance in error checking on DRAM.

Parity is virtually useless for these types of occasional problems, but ECCdetects problems in RAM quite well and can fix most of them on the fly. Anysize RAM stick can use ECC DRAM, but it is most common as 168-pin DIMMs.


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To take advantage of ECC RAM one needs a motherboard that is designedto use ECC.

DDR (Double Data Rate) SDRAMDDR maximizes output by using both the leading and falling edge of the clocktick to perform operations. This means that DDR can locate and pass anaddress in one tick as opposed to two.

The DDR module has 184 pins compared to the 168 pins on the standardSDRAM DIMM module. This means that a SDRAM cannot fit into a socketdesigned for a DDR module.

The logical speeds for DDR modules available are PC200, PC-266, and PC-333, which is a reference to their doubled bus speed.

SGRAM (Synchronous Graphic RAM)It operates in similar fashion to SD RAM but it is streamlined to work withgraphic cards. This RAM enables fast read and write operation for the graphicsprocessor when working with the information in the Video frame buffer.

VRAM (Video RAM)It is memory that is optimised for Video Cards where each memory cell is dualported. Therefore video data can be written to the RAM while the graphicsadapter simultaneously reads from it to refresh the display.

RDRAM (Rambus DRAM)Intel wanted faster RAM not just for higher-end performance machines includingservers, but standard desktops. Its choice was a new type of DRAM calledRambus DRAM (RDRAM).

The three versions of it are intended: PC 600 (clock speed: 300MHz), PC700(actually 711 or 356MHz), and PC 800 (400MHz).

Rambus comes in RIMMs, or Rambus Inline Memory Modules A RIMM differsfrom a SIMM or a DIMM in more than cost. Because these RIMMs can develophot spots apparently related to their speed of operation, each RIMM has a heatspreader cover plate to try to diffuse the heat. RDRAM RIMMs comes in 2 sizes:184 pin for desktops and 160 pins SO RIMM for laptops. RIMMs can't be usedon motherboards not designed with Rambus sockets in place. The Pentium 4with the Intel 850 chipset and above support Rambus memory.Static RAM (SRAM)Static RAM is a type of RAM that holds its data without external refresh, for aslong as power is supplied to the circuit. This is contrast to dynamic RAM (DRAM),which must be refreshed many times per second in order to hold its datacontents. SRAMs are used for specific applications within the PC, where theirstrengths outweigh their weaknesses compared to DRAM:


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• Simplicity: SRAMs don't require external refresh circuitry or other work inorder for them to keep their data intact.

• Speed: SRAM is faster than DRAM.

In contrast, SRAMs have the following weaknesses, compared to DRAMs:

• Cost: SRAM is, byte for byte, several times more expensive than DRAM.

• Size: SRAMs take up much more space than DRAMs (which is part of whythe cost is higher).

These advantages and disadvantages taken together obviously show thatperformance-wise, SRAM is superior to DRAM, and we would use it exclusivelyif only we could do so economically. Unfortunately, 32 MB of SRAM would beprohibitively large and costly, which is why DRAM is used for system memory.SRAMs are used for level 1 cache and level 2 cache memory, for which it isperfectly suited; cache memory needs to be very fast, and not very large.

SRAM is manufactured in a way rather similar to how processors are: highly-integrated transistor patterns photo-etched into silicon. Each SRAM bit iscomprised of between four and six transistors, which is why SRAM takes up muchmore space compared to DRAM, which uses only one (plus a capacitor).Because an SRAM chip is comprised of thousands or millions of identical cells,it is much easier to make than a CPU, which is a large die with a non-repetitivestructure. This is one reason why RAM chips cost much less than processors do.

Cache MemoryIn general, a processor is much more likely to need information again it hasrecently used, compared to a random piece of information in memory. Thisis the principle behind caching.

It's an small amount of fast memory placed between the processor and slowermain memory. Nowadays it is integrated within the CPU. Cache are used invarious forms to reduce the effective time required by a processor to accessaddresses, instructions or data that are normally stored in main memory.

Hit RateWhenever the CPU finds the data it needs in the cache then it is called a cachehit. When the CPU fails to find the data it needs in the cache that is calleda cache miss. The ratio of cache hits to cache misses is called that is calleda cache hit ratio. The cache hit ratio is a measure of the relative effectivenessof a cache. The better the cache design or the larger the cache the higher thecache hit ratio. A well-designed RAM cache normally will have a hit ratio ofgreater than 90 percent.

If a relatively small amount of fast static random access memory (SRAM), say


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32KB to 64KB, is enough for the CPU to find what it needs in this memory 90percent of the time, the effect is almost as if the computer were equipped onlywith fast SRAM even though a vast majority of its memory is much slower RAMby using a cache with a high hit rate, you can get the performance of acomputer with a large amount of fast memory and no RAM cache or the muchlower overall cost of a small amount of fast memory and a cache controller.

Layers of CacheThere are in fact many layers of cache in a modern PC. Each layer is closerto the processor and faster than the layer below it. Each layer also caches thelayers below it, due to its increased speed relative to the lower levels:

Level Devices CachedLevel 1 Cache Level 2 Cache, System RAM, Hard Disk / CD-ROMLevel 2 Cache System RAM, Hard Disk / CD-ROM

System RAM Hard Disk / CD-ROM

Hard Disk / CD-ROM --

The processor requests a piece of information. The first place it looks is in thelevel 1 cache, since it is the fastest. If it finds it there (called a hit on the cache),great; it uses it with no performance delay. If not, it's a miss and the level 2cache is searched. If it finds it there (level 2 "hit"), it is able to carry on withrelatively little delay. Otherwise, it must issue a request to read it from thesystem RAM. The system RAM may in turn either have the information availableor have to get it from the still slower hard disk or CD-ROM.

It is important to realize just how slow some of these devices are comparedto the processor. Even the fastest hard disks have an access time measuringaround 10 milliseconds. If it has to wait 10 milliseconds, a 200 MHz processorwill waste 2 million clock cycles! And CD-ROMs are generally at least 10 timesslower. This is why using caches to avoid accesses to these slow devices is socrucial.

Level 1 (Primary) CacheLevel 1 or primary cache is the fastest memory on the PC. It is in fact, builtdirectly into the processor itself. This cache is very small, generally from 8 KBto 64 KB, but it is extremely fast; it runs at the same speed as the processor.If the processor requests information and can find it in the level 1 cache, thatis the best case, because the information is there immediately and the systemdoes not have to wait.

Level 2 (Secondary) CacheThe level 2 cache is a secondary cache to the level 1 cache, and is larger


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and slightly slower. It is used to catch recent accesses that are not caught bythe level 1 cache, and is usually 64 KB to 2 MB in size. Level 2 cache is usuallyfound either on the same package as the processor itself (though it isn't in thesame circuit where the processor and level 1 cache are) or on the motherboardor as a daughterboard that inserts into the motherboard.

As more and more processors begin to include L2 cache into their architectures,Level 3 cache is now the name for the extra cache built into motherboardsbetween the microprocessor and the main memory.L3 cache is not found nowadays as its function is replaced by L2 cache. L3caches are found on the motherboard rather than the processor. It is keptbetween RAM and L2 cache.Quite simply, what was once L2 cache on motherboards now becomes L3cache when used with microprocessors containing built-in L2 caches.So if your system has L1,L2 and L3 cache data fetching will be L1->L2->L3->RAM ie. If data is not there in L1 it will check L2 then L3 then RAM...L3 cache has come into vogue with the advent of multi-core CPUs. Whereasthese chips will have both L1 and L2 caches for each separate core; there isa common fairly large L3 shared by all cores. It is usually the size of all othercaches combined or a few multiples of all other caches combined. It is alsoimplemented in DRAM. One unusual thing is that a multi-core chip that isrunning software that may not be capable of or need all cores will have a coreflush its caches into the L3 before that core goes dormant

Write Through and Write Back : There are also other Factors besidesthe hit rate that affect the efficiency of the cache. When the CPU writes newdata to the cache, the cache controller must update main memory with thenew data. By making sure that the information in the cache is the same as thatin main memory the cache controller is said to maintain cache coherency. Ifthe cache controller allows the data in the cache to differ from data in mainmemory, the data is said to be stale.

The simplest way to avoid having stale data is to make sure that every timethe CPU updates the cache, the data is automatically written through to themain memory. This is called a "write through cache". To prevent the CPU fromaccessing any data until the main memory has been updated, the cachecontroller must lock the CPU out of both the cache and the main memory untilthe write through has been completed. If the CPU needs to access the cacheor main memory before the write through is completed, the CPU must wait.This will slow the overall performance of the CPU.

One way to prevent this problem is for the cache controller to update a small


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LAB EXERCISE 10.1 : Memory Identification

Objective : To differentiate between the different memory modules.

Tasks:

1. Identify the different memory modules which are present by the number of slots inthe module.

2. Identify L1, L2, and L3, cache

3. Identify the difference between DDR2 and DDR3 RAM

but fast buffer instead of directly updating the main memory. Because thebuffer can be faster than the main memory, the cache controller can makethe cache available to the CPU sooner. This method of updating the mainmemory is called a "buffered or posted write through".

Another way to avoid the problem of making the CPU wait while the mainmemory is updated is for the cache controller to keep track of which data isstale and only update the memory when it must, not immediately after everymemory write. This technique, which is called write back or copy back, is moredifficult to implement but is faster than a posted wire through. The conceptof buffering, or posting, the writes can also be applied to the write back cacheto further increase its performance as well. This is the most complicated of alltechniques to implement, but it results in the fastest cache.

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CMS COMPUTER INSTITUTECMS COMPUTER

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Processors

Central Processing UnitThe Central Processing Unit (Normally calleda processor or CPU) is the brain of the PC. Itexecutes instructions, allowing a computer toperform all kinds of tasks. From burning CDsor DVDs to something as simple as a mouseclick, the CPU is always at work. Processorsconsist of two parts: The Arithmetic Unit, whichperforms math and logical operations, & theControl Unit, which decodes instructions. Overthe years, processors have become extremely

fast. AMD and Intel are the two primarymanufacturers, although other makers withnames such as Motorola, Via, and Cyrix andIDT have come and gone.

CPU technology constantly changes, probablyfaster than any other type of hardware. Thispage will highlight what I consider are the mainspecifications.

When looking at a CPU, you don't really see theprocessor itself. The little piece of silicon thatcontains the circuitry is very small. What youactually see is the package that it's in. Both AMDand Intel have had many types over the years.Packages are usually square with pinsunderneath that fit into holes on the CPU's slot.This arrangement is known as Pin Grid Array(PGA) and is now only used by AMD.



Fig. 11.1 Pin Grid Array

Fig. 11.2 PGA Slot

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TypesProcessors are designed to fit into a certain type of socket on the motherboard.Every socket has a name, indicating whether it's for an AMD or Intel CPU. Keepin mind that AMD and Intel have different socket designs, so their processorsare not interchangeable. But regardless of manufacturer, CPUs usually differin the number of pins used and are often named accordingly.

Socket Type Manufacturer

LGA 771 (Socket J) Intel (Xeon Server)

LGA 775 (Socket T) Intel

LGA 1156 (Socket H) Intel

LGA 1166 (Socket B) Intel

AM2 AMD

AM2+ AMD

AM3 AMD

Intel abandoned PGA years ago and now have the pins located on the slotsthemselves, called Land Grid Array (LGA).


AM2+ and AM3 mainly differ in terms of the memory each supports. AM2+supports DDR2 while AM3 supports DDR2 and DDR3, making it backward-compatible with the AM2+ motherboard.

Rates & Data TransferWhat characterizes a computer processor is its speed or rate - how fast it canexecute instructions. As of now, speed is measured in gigahertz (GHz), or

Fig. 11.3 Land Grid Array

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billions of cycles a second. Some CPU rates are 2.0 GHz, 2.40 GHz, and 3.20

GHz. These rates and others are obtained by using the motherboard's bus

speed.

CPUs contain a multiplier that when multiplied by the bus speed, yields the

appropriate CPU speed for a given motherboard. For example, if the speed

of a motherboard is 800 MHz, and the CPU multiplier is 4, then the processor's

speed is 800 x 4 = 3200 MHz or 3.2 GHz.

Because the CPU greatly determines the overall performance of a PC, the type

of processor and its speed are two of the main factors to look for when deciding

to buy a computer. But keep in mind there are other important things, such

as the amount of memory.

CPUs are either 32-bit or 64-bit. This means how much data that can be

processed in terms of bits. In computers data is composed of 1's and 0's (e.g.

01110010). Each individual 1 or 0 is called a bit. A 32-bit CPU can process

a max of 2^32 (2 raised to 32nd power) or about 4.3 billion bits per cycle.

A 64-bit processor 2^64 or about 18,400,000,000,000,000,000 of data per

cycle. The more data a computer can handle means improved performance.

The amount of memory supported by a processor is also determined by the

number of bits. Using the same math above, a 32-bit processor supports 2^32

or approximately 4 GB of memory.

Cache:

In addition to CPU speed, another important processor feature that influences

performance is the amount of cache (pronounced cash) it has. CPU cache is

memory set aside for the most frequently used data. There's Level 1, Level 2,

and Level 3 (commonly just called L1, L2, and L3). L1 uses extremely fast and

expensive SRAM (Static RAM) and is the smallest in size. L2 is slightly larger

in size. Both L1 and L2 are located on the processor. L3 is the largest and is

usually located outside the CPU and shared by all the cores. When data is

requested, the CPU first checks the L1 to see if it's there. If not it checks L2 and

so on. Accessing data in the cache is far more faster and efficient than fetching

it from RAM

Dual-processor, Dual Core & Multicore Processors:

Keeping it straight Dual-processor (DP) systems are those that contains two

separate physical computer processors in the same chassis. In dual-processor

systems, the two processors can either be located on the same motherboard

or on separate boards. In a dual-core configuration, an integrated circuit (IC)

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contains two complete computer processors. Usually, the two identical processors

are manufactured so they reside side-by-side on the same die, each with its

own path to the system front-side bus. Multi-core is somewhat of an expansion

to dual-core technology and allows for more than two separate processors.

Most computer processors today are dual core or multicore. Both terms are

generic for any processor that literally contains two or more CPUs in one

package. Both Intel and AMD produce versions of these processors. AMD's

Athlon x2, Turion x2, and Intel's Core 2 Duo and Core 2 Extreme are examples

of dual core CPUs. Multicore examples are the AMD Phenom x3 and x4 and

Intel's Core 2 Quad and the Core i7. These powerful CPUs allow users to run

several applications simultaneously as well as play the latest games.

HyperTransport:

AMD's HyperTransport Technology has been around since 2003. All of their

processors based on AMD64 architecture use HypertTransport. It eliminated

the front side bus (FSB) and took the memory controller, which was previously

on the chipset, and placed it on the processor. The old front side bus used one

data path from the CPU for memory and I/O (Input/Output). HTT implements

two separate data paths for memory and I/O. Also, unlike the FSB, data flow

between the CPU and the chipset can be sent and received at the same time.

In late 2012, Intel released the quad-core Core i7 CPU with its own version

of HyperTransport called QuickPath Interconnect (QPI). It basically does the

same thing as HTT but only uses DDR3 memory, and depending on which

model some support three memory channels. They also had to develop a new

chipset which includes PCI Express enhancements.

In addition supporting QPI, the Core i7 includes 64K L1 and 256K L2 cache

for each core, 8MB L3 shared cache, turbo boost, and HD boost for improved

high definition. It brings back the old hyper-threading. Before dual cores came

on the scene, hype-rthreading was used to make the operating system think

there were two processors. Since the i7 is quad-core hyper-threading makes

it seem as if there are eight cores.

All these combined make for an extremely fast system for multitasking, gaming

and multimedia needs.

The Core i7 computer processor comes in several variations, and it can get

confusing. There is also the Core i5 and Core i3. Below are tables showing

the Intel processors recently released in each class.

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i7 Series Released Speed Transfers/ Max. Amount Integrated CacheProcessor (All Sec & of Memory & HD SizeQuad Core & Number Number of GraphicsUse Hyper- Channelsthreading) Supported

i7-930 Q1 2010 2.8 GHZ; 4.8 GT/s 24 GB, N 8 MB3.46 GHz 3 Channelsw/TurboBoost

i7-960 Q4 2009 3.2 GHz; 4.8 GT/s 24 GB, N 8 MB3.46 GHz 3 Channelsw/TurboBoost


i7-870 Q3 2009 2.93GHz; 2.5 GT/s 16 GB, N 8 MB3.6 GHz 2 Channelsw/TurboBoost

i7-950 Q2 2009 3.06 GHz; 4.8 GT/s 24 GB, N 8 MB3.33 GHz 3 Channelsw/ TurboBoost



i7 Series Released Speed Transfers/ Max. Amount Integrated CacheProcessor (All Sec & of Memory & HD SizeQuad Core & Number Number of GraphicsUse Hyper- Channelsthreading) Supported

i7-980X Q1 2010 3.33 GHz; 6.4 GT/s 24 GB, N 12 MB (6 Cores) 3.6 GHz 3 Channels

w/TurboBoost

i7-975 Q2 2009 3.33 GHz; 6.4 GT/s 24 GB, N 8 MB(4 Cores) 3.6 GHz 3 Channels

w/TurboBoost

i7-965 Q4 2012 3.32 GHz; 6.4 GT/s 24 GB, N 8 MB(4 Cores) 3.46 GHz 3 Channels

w/TurboBoost

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CPU Speed Transfers/Sec L1 Cache L2 Cache Type of Memory Supported

Athlon II x3(Three Core) 3 GHz 4.4GT/s 128 KB 512 KB DDR2 & DDR3

Athlon II x4(Quad Core) 2.9 GHz 4.4 GT/s 128 KB 512 KB DDR2 & DDR3

Phenom II x2(Dual Core) 3.2 Ghz 4.0 GT/s 128 KB 512 KB DDR 2 & DDR3

Phenom II x3(Three Core) 2.8 GHz 4.0 GT/s 128 KB 512 KB DDR2 & DDR3

Phenom II x4(Quad Core) 3.4 GHz 4.0 GT/s 128 KB 512 KB DDR2 or DDR3 (Depends

on the type of socket)

i7 Extreme Released Speed Transfers/ Max. Amount Integrated CacheEdition Sec & of Memory & HD Size

Number Number of GraphicsChannelsSupported

i3-350 Q1 2010 2.93 GHz; 6.4 GT/s 16 GB, N 12 MB(Dual Core) 2 Channels

i3-540 Q2 2010 3.06 GHz; 6.4 GT/s 16 GB, N 8 MB(Dual Core) 2 Channels

i5-670 Q4 2010 3.46 GHz; 6.4 GT/s 16 GB, N 8 MB(Dual Core) 3.73 GHz 2 Channels

w/TurboBoost

Transfers/ Max. Amount Integrated CacheMobile Released Speed Sec & of Memory & HD SizeProcessor Number Number of Graphics

ChannelsSupported

i3-350M Q1 2010 2.26GHz; 2.5 GT/s 8 GB, Y 12 MB(Dual Core) (No Turbo 2 Channels

Boost)

i5-540 Q1 2010 2.53 GHz; 2.5 GT/s 8 GB, Y 8 MB(Dual Core) 3.066 2 Channels

w/TurboBoost

i7-670 Q1 2010 1.2 GHz; 2.5 GT/s 8 GB, Y 8 MB(Dual Core) 2.266GHz 2 Channels

w/TurboBoost

i7-670 Q3 2009 2 GHz; 2.5 GT/s 8 GB, N 8 MB(Dual Core) 3.2 GHz 2 Channels

w/TurboBoost

Believe or not, this is not the full list. To see others you can go to Intel's CPU page(http://www.intel.com/products/processor/index.htm?iid=subhdr +prod_proc). Below are tables

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Mobile CPUs Speed L1 Cache L2 Cache Type of Memory Supported

Turion x2 Ultra Max 2.4 GHz 2 MB DDR2

Turion Neo x2 1.6 GHz 128 KB 1 MB DDR 2

This is also not a complete list! For a full list check out AMD's desktopprocessors (http://products.amd.com/en-us/comparison/DesktopCPU.aspx) andlaptop processors (http://www.amd.com/us/products/notebook/platforms/Pages/notebook-platforms.aspx).

RISC AND CISCThe dominant architecture in the PC market, the Intel IA-32, belongs to theComplex Instruction Set Computing (CISC) design. The obvious reason for thisclassification is the "complex" nature of its Instruction Set Architecture (ISA). Themotivation for designing such complex instruction sets is to provide an instructionset that closely supports the operations and data structures used by Higher-Level Languages (HLLs).

Addressing Modes in CISCThe decision of CISC processor designers to provide a variety of addressingmodes leads to variable-length instructions. For example, instruction lengthincreases if an operand is in memory as opposed to in a register.

a. This is because we have to specify the memory address as part of instructionencoding, which takes many more bits.

b. This complicates instruction decoding and scheduling. The side effect ofproviding a wide range of instruction types is that the number of clocksrequired to execute instructions varies widely.

c. This again leads to problems in instruction scheduling and pipelining.

Evolution of RISCFor these and other reasons, in the early 1980s designers started looking atsimple ISAs. Because these ISAs tend to produce instruction sets with far fewerinstructions, they coined the term Reduced Instruction Set Computing (RISC).Even though the main goal was not to reduce the number of instructions, butthe complexity.Reduced Instruction Set Computing is a type of microprocessor architecturethat utilizes a small, highly-optimized set of instructions, rather than a morespecialized set of instructions often found in other types of architectures.

RISC VS CISC - An Example

The simplest way to examine the advantages and disadvantages of RISC

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architecture is by contrasting it with its predecessor, CISC (Complex InstructionSet Computing) architecture.

Multiplying Two Numbers in Memory. The main memory is divided intolocations numbered from (row) 1: (column) 1 to (row) 6: (column) 4. Theexecution unit is responsible for carrying out all computations. However, theexecution unit can only operate on data that has been loaded into one of thesix registers (A, B, C, D, E, or F). Let's say we want to find the product of twonumbers - one stored in location 2:3 and another stored in location 5:2 - andthen store the product back in the location 2:3.

Fig. 11.4 Representation of Storage Scheme for aGeneric Computer

The CISC Approach. The primary goal of CISC architecture is to complete atask in as few lines of assembly as possible. This is achieved by buildingprocessor hardware that is capable of understanding and executing a seriesof operations. For this particular task, a CISC processor would come preparedwith a specific instruction (say "MUL").

a. When executed, this instruction loads the two values into separate registers,multiplies the operands in the execution unit, and then stores the productin the appropriate register.

b. Thus, the entire task of multiplying two numbers can be completed with oneinstruction:


MUL 2:3, 5:2

c. MUL is what is known as a "complex instruction."

d. It operates directly on the computer's memory banks anddoes not require the programmer to explicitly call anyloading or storing functions.

e. It closely resembles a command in a higher level language.For instance, if we let "a" represent the value of 2:3 and"b" represent the value of 5:2, then this command isidentical to the C statement "a = a x b."

Advantage. One of the primary advantages of this systemis that the compiler has to do very little work to translate ahigh-level language statement into assembly. Because thelength of the code is relatively short, very little RAM isrequired to store instructions. The emphasis is put on buildingcomplex instructions directly into the hardware.

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The RISC Approach. RISC processors only use simple instructions that can beexecuted within one clock cycle. Thus, the "MUL" command described abovecould be divided into three separate commands:

a. "LOAD," which moves data from the memory bank to a register,

b. "PROD," which finds the product of two operands located within the registers,and

c. "STORE," which moves data from a register to the memory banks.

d. In order to perform the exact series of steps described in the CISCapproach, a programmer would need to code four lines of assembly:

LOAD A, 2:3LOAD B, 5:2PROD A, BSTORE 2:3, A

Analysis. At first, this may seem like a much less efficient way of completingthe operation. Because there are more lines of code, more RAM is needed tostore the assembly level instructions. The compiler must also perform morework to convert a high-level language statement into code of this form.a. Advantage of RISC. However, the RISC strategy also brings some veryimportant advantages. Because each instruction requires only one clock cycleto execute, the entire program will execute in approximately the same amountof time as the multi-cycle "MUL" command. These RISC "reduced instructions"require less transistors of hardware space than the complex instructions,leaving more room for general purpose registers. Because all of the instructionsexecute in a uniform amount of time (i.e. one clock), pipelining is possible.(1) Separating the "LOAD" and "STORE" instructions actually reduces the amountof work that the computer must perform.(2) After a CISC-style "MUL" command is executed, the processor automaticallyerases the registers. If one of the operands needs to be used for anothercomputation, the processor must re-load the data from the memory bank intoa register. In RISC, the operand will remain in the register until another valueis loaded in its place.b. The following table will differentiate both the architectures and based onthe analysis the overall advantage will be discussed.

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CISC RISC

Emphasis on hardware Emphasis on software

Includes multi-clock complex instruction Single-clock, reduced instruction only

Memory-to-memory: "LOAD" and Register to register: "LOAD" and "STORE" are"STORE" incorporated in instructions independent instructions

Small code sizes, high cycles per second Low cycles per second, large code sizes

Transistors used for storing complex instructions Spends more transistors on memory registers

Table Comparison of CISC and RISC ArchitecturesThe Performance Equation. The following equation is commonly used forexpressing a computer's performance ability:

a. CISC Approach. The CISC approach attempts to minimize the number ofinstructions per program, sacrificing the number of cycles per instruction.

b. RISC Approach. RISC does the opposite, reducing the cycles per instructionat the cost of the number of instructions per program

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The motherboard represents the logical foundation of the computer. In other

words, everything that makes a computer a computer must be attached to themotherboard.

From the CPU to storage devices, from RAM to printer ports, the motherboard

provides the connections that help them work together

Motherboards and theirComponents

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Figure 12-1 A typical ATXmotherboard with supportfor Nvidia's scalable linkinterface (SLI) technology.

The motherboard is essential to computer operation in large part because ofthe two major buses it contains: the system bus and the I/O bus. Together, thesebuses carry all the information between the different parts of the computer.


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The System Bus and I/O BusThe system bus carries four different types of signals throughout the computer:* Data* Power* Control* Address

The Bus

The CPU has to be able to send various data values, instructions, andinformation to all the devices and components inside your computer as wellas the different peripherals and devices attached. If you look at the bottomof a motherboard you'll see a whole network of lines or electronic pathwaysthat join the different components together. These electronic pathways arenothing more than tiny wires that carry information, data and different signalsthroughout the computer between the different components. This network ofwires or electronic pathways is called the 'Bus'.

That's not that difficult to comprehend, but you've probably heard mention ofthe internal bus, the external bus, expansion bus, data bus, memory bus, PCIbus, ISA bus, address bus, control bus,… it really can get quite confusing.

A computer's bus can be divided into two different types, Internal and External.

The Internal Bus connects the different components inside the case: The CPU,system memory, and all other components on the motherboard. It's alsoreferred to as the System Bus.

The External Bus connects the different external devices, peripherals, expansionslots, I/O ports and drive connections to the rest of the computer. In other words,the External Bus allows various devices to be added to the computer. It allowsfor the expansion of the computer's capabilities. It is generally slower than thesystem bus. Another name for the External Bus, is the Expansion Bus.

So now we know the bus is just a bunch of tiny wires (traces and electronicpathways). One bunch carries info around to the different components on themotherboard, and another bunch of wires connects these components to thevarious devices attached to the computer.

What kind of stuff travels on the bus? For one thing, data. Data has to beexchanged between devices. Some of the electronic pathways or wires of theInternal Bus or the External Bus are dedicated to moving data. These dedicatedpathways are called the Data Bus.

Data is stored, manipulated and processed in system memory. System memoryis like a vast sea of information full of fish (data). Your computer has to moveinformation in and out of memory, and it has to keep track of which data is

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stored where. The computer knows where all the fishes are, but it has to transmitthat information to the CPU and other devices. It has to keep a map of thedifferent address locations in memory, and it has to be able to transmit anddescribe those memory locations to the other components so that they canaccess the data stored there. The info used to describe the memory locationstravels along the address bus. The size, or width of the address bus directlycorresponds to the number of address locations that can be accessed. Thissimply means that the more memory address locations that a processor canaddress, the more RAM it has the capability of using. It makes sense, right?

A 286 with a 16 bit address bus can access over 16 million locations, or 16Mb of RAM. A 386 CPU with a 32 bit address bus can access up to 4 GB ofRAM. Of course, at the present time, due to space and cost limitationsassociated with the average home computer, 4GB of RAM is not practical. But,the address bus could handle it if it wanted to! Another name for the addressbus is the memory bus.

Form Factors

Although all motherboards have some features in common, their layout andsize varies a great deal. The most common motherboard designs in currentuse include ATX, Micro ATX, BTX, and NLX. Some of these designs feature risercards and daughterboards. The following sections cover the details of thesedesigns.

ATX and Micro ATX

The ATX family of motherboards has dominated desktop computer designssince the late 1990s. ATX stands for "Advanced Technology Extended," and itreplaced the AT and Baby-AT form factors developed in the mid 1980s for theIBM PC AT and its rivals. ATX motherboards have the following characteristics:

• A rear port cluster for I/O ports

• Expansion slots that run parallel to the short side of the motherboard

• Left side case opening (as viewed from the front of a tower PC)

There are four members of the ATX family, listed in Table 11-1. In practice,though, the Mini-ATX design is not widely used.

Table 12-1 ATX Motherboard Family Compariso

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BTXOne problem with the ATX design has been the issue of system cooling. BecauseATX was designed more than a decade ago, well before the development oftoday's faster components, it's been difficult to properly cool the hottest-runningcomponentsin a typical system: the processor, memory modules, and theprocessor's voltage regulator circuits.

To enable better cooling for these devices, and to promote better systemstability, the BTX family of motherboard designs was introduced in 2004.Compared to ATX motherboards, BTX motherboards have the following:

" Heat-producing components such as the process, memory, chipset, andvoltage regulator are relocated to provide straight-through airflow fromfront to back for better cooling.

" The processor socket is mounted at a 45-degree angle to the front of themotherboard to improve cooling.

" A thermal module with a horizontal fan fits over the processor for cooling.

" The port cluster is moved to the rear left corner of the motherboard.

" BTX cases include multiple rear and side air vents for better cooling.

" Because of the standardization of processor and memory locations, it's easyto use the same basic design for various sizes of BTX motherboards; thedesigner can just add slots.

" BTX tower cases use a right-opening design as viewed from the front.Although BTX designs are easier to cool than ATX designs, the developmentof cooler-running processors has enabled system designers to continue tofavor ATX. There are relatively few BTX-based motherboards and systemscurrently on the market.

Fig. 12-2 compares typicalATX and BTX motherboardlayouts to each other.


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Figure 12-2 The ATX motherboard family includes ATX (largest), microATX, andflexATX (smallest). The BTX motherboard family includes BTX, microBTX, nanoBTX,and picoBTX (smallest).

NLXNLX motherboards are designed for quick replacement in corporateenvironments. They use a riser card that provides power and expansion slotsthat connect to the right edge of the motherboard (as viewed from the front).NLX motherboards have a two-row cluster of ports along the rear edge of themotherboard.

Most systems that use NLX motherboards are considered obsolete. Figure 12-3 illustrates a typical NLX motherboard and riser card.

Fig. 12-3 A typical NLXmotherboard and riser card. Riser Cards and Daughterboards

Riser cards and daughterboards provide two different methods for providingaccess to motherboard-based resources. In current slimline or rackmountedsystems based on ATX or BTX technologies, riser cards are used to makeexpansion slots usable that would otherwise not be available because ofclearances inside the case. Riser card designs can include one or moreexpansion slots, and are available in PCI, PCI-X (used primarily in workstationand server designs), and PCI-Express designs. Figure 12-4 shows two typicalimplementations of riser card designs.


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The term daughterboard is sometimes used to refer to riser cards, butdaughterboard can also refer to a circuit board that plugs into another boardto provide extra functionality. For example, some small form factor motherboardssupport daughterboards that add additional serial or Ethernet ports, and somestandardsize motherboards use daughterboards for their voltage regulators.

Fig. 12-4 Examples ofsingle-slot and multi-slotriser cards.

Integrated I/O Ports

Motherboards in both the ATX and BTX families feature a variety of integratedI/O ports. These are found in as many as three locations: all motherboardsfeature a rear port cluster (see Figure 12-5 for a typical example), and manymotherboards also have additional ports on the top of the motherboard thatare routed to header cables accessible from the front and rear of the system

Fig. 12-5 A port cluster on a late-model ATX system.



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Most recent motherboards include the following ports in their port cluster:

• Serial (COM)

• Parallel (LPT)

• PS/2 mouse

• PS/2 keyboard

• USB 2.0 (Hi-Speed USB)

• 10/100 or 10/100/1000 Ethernet (RJ-45)

• Audio

So-called "legacy-free" motherboards might omit some or all of the legacyports (serial, parallel, PS/2 mouse and keyboard), a trend that will continueas devices using these ports have been replaced by devices that plug intoUSB ports. Some high-end systems might also include one or more FireWire(IEEE-1394a) ports, and systems with integrated video include a VGA or DVI-I video port and an S-Video or HDMI port for TV and home theater use.

Figure 12-5 illustrates a port cluster from a typical ATX system, but note thatBTX systems use similar designs.

Some integrated ports use header cables to provide output. Figure 12-6shows an example of 5.1 surround audio ports on a header cable. The headercable plugs into the motherboard and occupies an empty expansion slot.

Fig. 12-6 This header cable provides support for 5.1 surround analog audioand digital audio.

Memory SlotsModern motherboards include two ormore memory slots, as seen in Figures12-1 and 12-2. At least one memoryslot must contain a memory module,or the system cannot start or function.

Memory slots vary in design accordingto the type of memory the systemsupports. Older systems that use SDRAMuse three-section memory slotsdesigned for 168-pin memorymodules. Systems that use DDR SDRAMuse two-section memory slots designedfor 184-pin modules. Systems that useDDR2 SDRAM use two section memoryslots designed for 240-pin modules.


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Each memory slot includes locking levers that secure memory in place. Whenmemory is properly installed, the levers automatically swivel into place

Expansion SlotsMotherboards use expansion slots to provide support for additional I/Odevices and high-speed video/graphics cards. The most common expansionslots on recent systems include peripheral component interconnect (PCI),advanced graphics port (AGP), and PCI-Express (also known as PCIe). Somesystems also feature audio modem riser (AMR) or communications networkriser (CNR) slots for specific purposes

Fig. 12-7 Installing memorymodules. PCI Slots

The PCI slot can be used for many types of add-on cards, including network,video, audio, I/O and storage host adapters for SCSI, PATA, and SATA drives.There are several types of PCI slots, but the one found in desktop computersis the 32-bit slot running at 33MHz (refer to Figure 12-8 in the next section).

AGPThe AGP slot was introduced as a dedicated slot for high-speed video (3Dgraphics display) in 1996. Since 2005, the PCI Express x16 slot (described inthe next section) has replaced it in most new systems. There have been severalversions of the AGP slot, reflecting changes in the AGP standard, as shown inFigure 12-8. Note that all types of AGP slots can temporarily "borrow" systemmemory when creating 3D textures.

Note that the AGP 1x/2x and AGP 4x/8x slots have their keys in differentpositions. This prevents installing the wrong type of AGP card into the slot. AGP


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1x/2x cards use 3.3V, whereas most AGP 4x cards use 1.5V. AGP 8x cards use0.8 or 1.5V. The AGP Pro/Universal slot is longer than a normal AGP slot tosupport the greater electrical requirements of AGP Pro cards (which are usedin technical workstations). The protective cover over a part of the slot isintended to prevent normal AGP cards from being inserted into the wrong partof the slot. The slot is referred to as a universal slot because it supports both3.3V and 1.5V AGP cards.

Fig. 12-8 PCI slots compared to an AGP 1x/2x slot (top), an AGP 4x/8x slot (middle), and an AGP Pro/Universal slot (bottom).


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PCIe (PCI-Express) SlotsPCI Express (often abbreviated as PCIe or PCIE) began to replace both PCIand AGP slots in new system designs starting in 2005. PCI Express slots areavailable in four types:

• x1 • x4 • x8 • x16The most common versions include the x1, x4, and x16 designs, as shown inFigure 12-9

Fig. 12-9 PCI Express slotscompared to a PCI slot.

PCI Express x1 and x4 slots are designed to replace the PCI slot, and x8 andx16 are designed to replace the AGP slot. Table 12-2 compares the performanceof PCI, AGP, and PCI Express slots.

Table 12-2 Technical Information About Expansion Slot Types

Slot Type Performance Suggested Uses

PCI 133MBps Video, network, SCSI, sound card

AGP 1x 266MBps Video

AGP 2x 533MBps Video

AGP 4x 1,066MBps Video

AGP 8x 2,133MBps Video

PCIe x1 500MBps* Network, I/O

PCIe x2 1,000MBps* Network

PCIe x8 4,000MBps* SLI video

PCIe x16 8,000MBps* Video (including SLI, CrossFire)


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AMR and CNR SlotsSome motherboards have one of two specializedexpansion slots in addition to the standard PCI, PCIExpress, or AGP slots. The audio modem riser (AMR)slot (see Figure 12-10) enables motherboarddesigners to place analog modem and audioconnectors and the codec chip used to translatebetween analog and digital signals on a small risercard. AMR slots are frequently found on older systemswith chipsets that integrate software modems (seeFigure 12-11) and audio functions

Fig. 12-10 An AMR slot and PCI slot (left) compared to a CNR slotand PCI slot (right). Very few AMR riser cards were ever sold, butsome motherboard vendors have bundled CNR riser cards withtheir motherboards to provide six-channel audio output and otherfeatures.

Fig. 12-11 An AMR riser card used for softmodem support (left) and a CNR riser cardused for six-channel (5.1) analog and digitalaudio support (right).



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The AMR was replaced by the communications network riser (CNR) slot (seeFigure 12-10), a longer design that can support up to six-channel audio, S/PDIF digital audio, and home networking functions. Some vendors have usedthe CNR slot to implement high-quality integrated audio as shown in Figure12-11.The AMR or CNR slot, when present, is usually located on the edge of themotherboard.The AMR slot was often found on Pentium III or AMD Athlon-based systems, while the CNR slot was used by some Pentium 4-based systems.Current systems integrate network and audio features directly into themotherboard and its port cluster, making both types of slots obsolete.

Mass Storage InterfacesMotherboards also include mass storage interfaces such as EIDE/PATA, SATA,and SCSI. The following sections compare and contrast the appearance andfunctionality of these interfaces. Table 12-3 provides a quick overview oftechnical information about these interfaces.

Table 12-3 Technical Information About Mass Storage Interfaces

Interface Performance Suggested Uses

SATA 1st 1.5Gbps Hard disk, rewritable DVDgeneration

SATA 2nd 3.0Gbps Hard disk, rewritable DVDgeneration

PATA/IDE 1.0-1.3Gbps Rewritable DVD, rewritable CD, Zip, JAZ, REV, tape

SCSI 1.6-3.2Gbps* Hard disk, tape backup

Note: *Current Ultra 160 and Ultra 320 SCSI standards; older standards are much slower.

EIDE/PATAUntil recently, most motherboards included two or more EIDE/PATA (also knownas ATA/IDE) host adapters for PATA devices such as hard disks, CD or DVDdrives, tape backups, and removable-media drives. Each host adapter usesa 40-pin interface similar to the one shown in Figure 12-12, and can controlup to two drives.

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Fig. 12-12 PATA and SATAhost adapters on a typicalmotherboard.

Most recent systems use a plastic skirt around the PATA connector with a notchon one side. This prevents improper insertion of a keyed PATA (ATA/IDE) cable.However, keep in mind that some older systems have unskirted connectors andsome older ATA/IDE cables are not keyed. To avoid incorrect cable connections,be sure to match pin 1 on the PATA host adapter to the red-striped edge ofthe PATA ribbon cable.

On systems with a third EIDE/PATA host adapter, the additional host adapteris typically used for a RAID 0 or RAID 1 drive array. See your system or mother-board documentation for details. Most current systems now have only oneEIDE/PATA host adapter, as the industry is transitioning away from EIDE/PATAto SATA interfaces for both hard disk and DVD drives.

SATAMost recent systems have anywhere from two to as many as eight Serial ATA(SATA) host adapters. Each host adapter controls a single SATA drive, such asa hard disk or rewritable DVD drive. The original SATA host adapter designdid not have a skirt around the connector, making it easy for the cable tobecome loose. Many late-model systems now use a skirted design for the hostadapter (see Figure 12-13).


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Fig. 12-13 Most late modelsystems include multipleSATA host adapters withskirted connectors.

SCSISCSI (Small Computer Systems Interface) is a more flexible drive interface thanPATA (ATA/IDE) because it can accommodate many devices that are not harddisk drives. The following have been common uses for SCSI:

" High-performance and high-capacity hard drives

" Image scanners

" Removable-media drives such as Zip, Jaz, and Castlewood Orb

" High-performance laser printers

" High-performance optical drives, including CD-ROM, CD-R, CD-RW, DVD-ROM, and others

So-called Narrow SCSI host adapters (which use an 8-bit data channel) canaccommodate up to seven devices of different varieties on a single connectoron the host adapter through daisy-chaining. Wide SCSI host adapters use a16-bit data channel and accommodate up to 15 devices on a single connectoron the host adapter through daisy-chaining. Narrow SCSI devices and hostadapters use a 50-pin or(rarely) a 25-pin cable and connector, while Wide SCSI devices use a 68-pincable and connector.


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Several years ago, SCSI host adapters were found on some high-end desktopand workstation motherboards. However, most recent systems use SATA inplace of SCSI, and SCSI host adapters and devices are now primarily usedby servers. Currently, SCSI is used primarily for high-performance hard disksand tape backups.Systems with onboard SCSI host adapters might have one or more 50-pin or68- pin female connectors similar to those shown in Figure 12-14

Plug and PlayPlug and Play (PnP) means that you can connect a device or insert a card intoyour computer and it is automatically recognized and configured to work inyour system. PnP is a simple concept, but it took a concerted effort on the partof the computer industry to make it happen. Intel created the PnP standardand incorporated it into the design for PCI. But it wasn't until several years laterthat a mainstream operating system, Windows 95, provided system-levelsupport for PnP. The introduction of PnP accelerated the demand for computerswith PCI, very quickly supplanting ISA as the bus of choice.

PnP requires three things:

" PnP BIOS - The core utility that enables PnP and detects PnP devices. TheBIOS also reads the ESCD for configuration information on existing PnPdevices.

" Extended System Configuration Data (ECSD) - A file that contains informationabout installed PnP devices.

" PnP operating system - Any operating system, such as Windows 95/98/ME,that supports PnP. PnP handlers in the operating system complete theconfiguration process started by the BIOS for each PnP device.

PnP automates several key tasks that were typically done either manually orwith an installation utility provided by the hardware manufacturer. These tasksinclude the setting of:


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" Interrupt requests (IRQ) - An IRQ, also known as a hardware interrupt, isused by the various parts of a computer to get the attention of the CPU.For example, the mouse sends an IRQ every time it is moved to let the CPUknow that it's doing something. Before PCI, every hardware componentneeded a separate IRQ setting. But PCI manages hardware interrupts atthe bus bridge, allowing it to use a single system IRQ for multiple PCIdevices.

" Direct memory access (DMA) - This simply means that the device isconfigured to access system memory without consulting the CPU first.

" Memory addresses - Many devices are assigned a section of systemmemory for exclusive use by that device. This ensures that the hardwarewill have the needed resources to operate properly.

" Input/Output (I/O) configuration - This setting defines the ports used by thedevice for receiving and sending information.

The overall effect of PnP has been to greatly simplify the process of upgradingyour computer to add new devices or replace existing ones.

PnP WorkingLet's say that you have just added a new PCI-based sound card to yourWindows 98 computer. The different steps are as follows

1. You open up your computer's case and plug the sound card into an emptyPCI slot on the motherboard.

2. You close the computer's case and power up the computer.

3. The system BIOS initiates the PnP BIOS.

4. The PnP BIOS scans the PCI bus for hardware. It does this by sending outa signal to any device connected to the bus, asking the device who it is.

5. The sound card responds by identifying itself. The device ID is sent backacross the bus to the BIOS.

6. The PnP BIOS checks the ESCD to see if the configuration data for the soundcard is already present. Since the sound card was just installed, there isno existing ESCD record for it.

7. The PnP BIOS assigns IRQ, DMA, memory address and I/O settings to thesound card and saves the data in the ESCD.

8. Windows 98 boots up. It checks the ESCD and the PCI bus. The operatingsystem detects that the sound card is a new device and displays a smallwindow telling you that Windows has found new hardware and is determiningwhat it is.

9. If it is able to determine what the device is, it displays the name of the device

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and attempts to install the driver (the software that enables the device tocommunicate with the operating system). You may be asked to insert a diskwith the driver on it or tell Windows where to find the driver software. IfWindows cannot determine what the device is, it provides a dialog windowso that you can specify what type of device it is and load a driver to runit.

10.Once the driver is installed, the device should be ready for use. Somedevices may require that you restart the computer before you can use them.

Choosing the Best Motherboard for the JobSo, how do you go about choosing the best motherboard for the job? Followthis process:Step 1. Decide what you want the motherboard (system) to do. Because mostof a computer's capabilities and features are based on the motherboard, youneed to decide this first.

Some examples:If you need high CPU performance, you must choose a motherboard thatsupports the fastest dual-core or multi-core processors available. If you wantto run a 64-bit (x64) operating system, you need a motherboard that supports64-bit processors and more than 4GB of RAM. If you want to run fast 3Dgaming graphics, you need a motherboard that supports NVIDIA's SLI or ATI'sCrossFire multi-GPU technologies. If you want to support multimedia uses suchas video editing, you'll prefer a motherboard with onboard IEEE-1394a(FireWire 400). If you are building a system for use as a home theater, a systemwith HDMI graphics might be your preferred choice.

Step 2. Decide what form factor you need to use. If you are replacing anexisting motherboard, the new motherboard must fit into the case (chassis)being vacated by the old motherboard and (ideally) be powered by the existingpower supply. If you are building a new system, though, you can choose theform factor needed.

Some examples:Full-size ATX or BTX motherboards provide the most room for expansion butrequire mid-size or full-size tower cases. If no more than three expansion slotsare needed, micro ATX or micro BTX systems fit into mini-tower cases thatrequire less space and can use smaller, lessexpensive power supplies. If onlyone slot (or no slots) are needed, picoATX or picoBTX systems that fit into smallform factor cases require very little space.

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Troubleshooting MotherboardsWhen you're troubleshooting a computer, there is no shortage of places to lookfor problems. However, because the motherboard is the "home" for the mostessential system resources, it's often the source of many problems. If you seethe following problems, consider the motherboard as a likely place to lookfor the cause:

" System will not start- When you push the power button on an ATX or BTXsystem, the computer should start immediately. If it doesn't, the problemcould be motherboard-related.

" Devices connected to the port cluster don't work- If ports in the port clusterare damaged or disabled in the system BIOS configuration (CMOS setup),any devices connected to the port cluster will not work.

" Devices connected to header cables don't work- If ports connected to theheader are not plugged into the motherboard, are damaged, or aredisabled in the system BIOS configuration (CMOS setup), any devicesconnected to these ports will not work.

" Mass storage drives are not recognized or do not work- If mass storageports on the motherboard are not properly connected to devices, aredisabled, or are not configured properly, drives connected to these portswill not work.

" Memory failures- Memory failures could be caused by the modulesthemselves, or they could be caused by the motherboard.

" Problems installing aftermarket processor heat sinks or replacement cards-You cannot assume that every device fits every system.

The following sections help you deal with these common problems.

System Will Not StartIf the computer will not start, check the following:Incorrect front panel wiring connections to the motherboardLoose or missing power leads from power supplyLoose or missing memory modulesLoose BIOS chipsIncorrect connection of PATA/IDE cables to onboard host adapterDead short in systemIncorrect positioning of a standoffLoose screws or slot covers

The following sections describe each of these possible problems.

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Incorrect Front Panel Wiring Connections to the Motherboard The power switchis wired to the motherboard, which in turn signals the power supply to start.If the power lead is plugged into the wrong pins on the motherboard, or hasbeen disconnected from the motherboard, the system will not start and youwill not see an error message.

Check the markings on the front panel connectors, the motherboard, or themotherboard/system manual to determine the correct pinouts and installation.Figure 12-15 shows typical motherboard markings for front panel connectors.

Fig. 12-15 A typical two-row front panel connectoron a motherboard.

Loose or Missing Power Leads from Power Supply Modern power supplies oftenhave both a 20- or 24-pin connection and a four- or eight-pin connection tothe motherboard. If either or both connections are loose or not present, thesystem cannot start and you will not see an error message.Loose or Missing Memory Modules If the motherboard is unable to recognizeany system memory, it will not start properly. Unlike the other problems, youwill see a memory error message. Make sure memory modules are properlylocked into place, and that there is no corrosion on the memory contacts onthe motherboard or on the memory modules themselves. To remove corrosionfrom memory module contacts, remove the memory modules from themotherboard and gently wipe the contacts off to removeany built-up film or corrosion. An Artgum eraser (but not the conventionalrubber or highly abrasive ink eraser) can be used for stubborn cases. Be sureto rub in a direction away from the memory chips to avoid damage. Reinsert


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the modules and lock them into place.

Loose BIOS Chips Socketed motherboard chips that don't have retainingmechanisms, such as BIOS chips, can cause system failures if the chips workloose from their sockets. The motherboard BIOS chip (see Figure 12-16) isresponsible for displaying boot errors, and if it is not properly mounted in itssocket, the system cannot start and no error messages will be produced (notethat many recent systems have surface-mounted BIOS chips).The cycle of heating (during operation) and cooling (after the power is shutdown) can lead to chip creep, in which socketed chips gradually loosen in thesockets. To cure chip creep, push the chips back into their sockets. Use evenforce to press a square BIOS chip into place. On older systems that userectangular BIOS chips, alternately push on each end of the chip until the chipis securely mounted.

Incorrect Connection of PATA/IDE Cables to Onboard Host Adapter Manysystems are designed to wait for a response from a device connected to a PATA/IDE host adapter on the motherboard before continuing to boot. If the PATA/IDE cable is plugged in incorrectly, the system will never get the neededresponse, and some systems will not display an error message.

Fig. 12-19 If a socketed BIOS chip like this one becomes loose, the system will not boot.


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Make sure pin 1 on the cable is connected to pin 1 on the PATA/IDE deviceand the corresponding host adapter on the system. Check the motherboardmanual for the position of pin 1 on the motherboard's host adapter if the hostadapter is not marked properly.

Dead Short (Short Circuit) in System A dead short (short circuit) in your systemwill prevent a computer from showing any signs of life when you turn it on.Some of the main causes for dead shorts that involve motherboards include

" Incorrect positioning of a standoff

" Loose screws or slot covers

The following sections describe both possible causes.

Incorrect positioning of a standoffBrass standoffs should be lined up with the mounting holes in the motherboard(refer to Figure 12-17 for typical locations). Some motherboards have twotypes of holes: plain holes that are not intended for use with brass standoffs(they might be used for heat sink mounting or for plastic standoffs) andreinforced holes used for brass standoffs. Figure 12.17 compares these holetypes.

If a brass standoff is under a part of the motherboard not meant for mounting,such as under a plain hole or under the solder connections, the standoff couldcause a dead short that prevents the system from starting

Fig. 12-17Mounting holescompared to otherholes on a typicalmotherboard.


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Loose screws or slot covers

Leaving a loose screw inside the system and failing to fasten a slot cover or

card in place are two common causes for dead shorts, because if these metal

parts touch live components on the motherboard, your system will short out

and stop working.

The solution is to open the case and remove or secure any loose metal parts

inside the system. Dead shorts also can be caused by power supply-related

problems.

Devices Connected to the Port Cluster Don't Work

The port cluster (refer to Figure 12-5) provides a "one-stop shop" for most I/

O devices, but if devices plugged into these ports fail, check the disabled ports

and possible damage to a port in the port cluster, as described in the following

sections.

Disabled Port If a port hasn't been used before, and a device connected to

it doesn't work, be sure to check the system's BIOS configuration to determine

if the port is disabled. This is a particularly good idea if the port is a legacy

port (serial/COM, parallel/LPT) or is the second network port. Ports can also

be disabled using Windows Device Manager.

Damage to a Port in the Port Cluster If a port in the port cluster has missing

or bent pins, it's obvious that the port is damaged, but don't expect all types

of damage to be obvious. The easiest way to see if a port in the port cluster

is damaged is to follow these steps:

Step 1. Verify that the port is enabled in the system BIOS and Windows Device

Manager.

Step 2. Make sure the device cable is connected tightly to the appropriate port.

Use the thumbscrews provided with serial/COM, parallel/LPT, and VGA or DVI

video cables to assure a proper connection.

Step 11. If the device fails, try the device on another port or another system.

If the device works, the port is defective. If the device doesn't work, the device

or the device's cable is defective.

To solve the problem of a defective port, use one of these solutions:

" Replace the motherboard with an identical model- This is the best solution

for long-term use. Note that if you replace the motherboard with a different

model you might need to reinstall Windows, or, at a minimum, reinstall

drivers and reactivate Windows and some applications.

" Install an add-on card to replace the damaged port- This is quicker than

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replacing the motherboard, but if you are replacing a legacy port such as

serial/COM or parallel/LPT, it can be expensive. If the device that plugged

into a legacy port can also use a USB port, use a USB port instead.

" Use a USB/legacy port adapter- Port adapters can be used to convert

serial/COM or parallel/LPT devices to work on USB ports. However, note

that some limitations might be present. Generally, this is the least desirable

solution.

Devices Connected to Header Cables Don't Work

Before assuming that a port that uses a header cable is defective or disabled,

make sure the header cable is properly connected to the motherboard. If the

system has just been assembled, or if the system has recently undergone

internal upgrades or servicing, it's possible the header cable is loose or

disconnected.

If the header cable is properly connected to the motherboard, follow the steps

in the previous section to determine the problem and solution.

Devices Connected to Header Cables Don't Work

Before assuming that a port that uses a header cable is defective or disabled,

make sure the header cable is properly connected to the motherboard. If the

system has just been assembled, or if the system has recently undergone

internal upgrades or servicing, it's possible the header cable is loose or

disconnected.

If the header cable is properly connected to the motherboard, follow the steps

in the previous section to determine the problem and solution.

Mass Storage Devices Do Not Work Properly

Mass storage devices that connect to SATA, PATA/IDE, or SCSI host adapters

on the motherboard will not work if either of the following are true, as described

in the next sections:

" Mass storage ports are disabled in system BIOS or Windows

" Data cables are not properly connected to the motherboard or drives

Mass Storage Ports Disabled in System BIOS or Windows Before assuming a

mass storage device is defective, be sure to verify whether the port has been

disabled in the system BIOS configuration (CMOS setup or in Windows Device

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Manager). If you cannot connect the device to another port, enable the port

and retry the device. To learn how to manage integrated ports using the system

BIOS setup.

Data or Power Cables Are Not Properly Connected to the Motherboard or

Drives If internal upgrades or servicing has taken place recently, it's possible

that data or power cables have become loose or disconnected from the mass

storage host adapters on the motherboard or the drives themselves. Before

reconnecting the cables, shut down the computer and disconnect it from AC

power.

Memory Failures

Memory failures could be caused by the modules themselves, or they could

be caused by the motherboard. For more information on memory problems

and motherboards, see the section "Loose or Missing Memory Modules," earlier

in this chapter.

Card, Memory, or Heat Sink Blocked by Motherboard Layout

Internal clearances in late-model systems are very tight, and if you attempt

to install some types of hardware in some systems, such as an oversized

processor heat sink or a very large video card, it might not be possible because

of the motherboard's layout.

Before purchasing an aftermarket heat sink, check the clearances around the

processor. Be especially aware of the location of capacitors and the voltage

regulator; if the heat sink is too large, it could damage these components

during installation. To help verify that an aftermarket heat sink will fit properly,

remove the original heat sink from the processor and take it with you to

compare its size to the aftermarket models you are considering.

Before purchasing an expansion card, check the slot clearance to be sure the

card will fit into the desired expansion slot. In some cases, you might need

to move a card from a neighboring slot to make room for the cooling fan

shroud on some high-performance graphics cards.

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A Quick Tour Through a Typical CMOS Setup

Every maker of BIOS has a different CMOS setup program.

They all say basically the same thing; you just have to

be comfortable "poking around". To avoid doing

something foolish, do not save anything unless you have

it set correctly. When you boot a machine with Award

BIOS you will see something similar to Fig. 12.17 and

at the bottom of the screen it shows the way to enter the

CMOS Setup.

Press DEL and the screen in Fig. 12.18 will appear. you

are now in the Main menu of the Award CMOS setup

program! This program is stored on the ROM chip, but

it solely edits the data on the CMOS chip.

The first BIOS was nothing more than a standard CMOS setup. Today, virtually

all computers have many extra CMOS settings. They control items such as

memory management, password and booting options, diagnostic and error

handling, and power management. The following section takes a quick tour

of a fairly typical Award CMOS setup program. Remember that your CMOS

setup will almost certainly look at least a little different from the one seen here

in the Fig. 12.18 unless you happen to have the same BIOS.

Motherboard makers buy a basic BIOS from Award and can add or remove

options (Award calls them "modules") based on the needs of the motherboard.

This can cause problems, as seemingly identical CMOS setups can be extremely

different. Options that show up on one computer might be missing from

another.© CMS INSTITUTE 2012

Fig. 12.19 Main Menu

Fig. 12.18 Press DEL toenter SETUP


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Standard CMOS FeaturesSelect Standard CMOS Features, andthe standard CMOS screen willappear (see Fig. 12.20)

On the Standard CMOS Featuresscreen you can change floppy drive,hard drive, and date/time settings.At this point, the only goal is tointroduce you to CMOS and to makesure you can access the CMOS setupon your PC.

Fig. 12.20 shows the same standardCMOS screen with a Phoenix BIOS.note that Phoenix calls it "Main".

Advanced BIOS FeaturesAdvanced BIOS Features is thedumping ground for all the settingsthat aren't covered in the Standardmenu but don't fit nicely under anyother screen. This screen varies wildlyfrom one system to the next. We usethis screen most often to select theboot options (Fig. 12.21).

Advanced Chipset FeaturesThis screen strikes fear into everyonebecause it deals with extremely low-


Fig. 12.20 Standard CMOSfeatures Screen

Fig. 12.21 Phoenix BIOSMain Screen


level chipset functions. Avoid this screen unless a high-level tech (like amotherboard maker's tech support) explicitly tells you to do something in here

Integrated PeripheralsIt allows to configure, enable, or disable the onboard ports, such as the serialand parallel ports.

Power Management SetupThe power management settings control how and when devices turn off andback on to conserve power.

PnP/PCI ConfigurationsThe commonly used PnP/PCI Confi-gurations are used for setting certain

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resources called "IRQs" to prevent thesystem from taking that resource awayfrom a device that needs it.

And the Rest of the CMOSSettings...The other options on the main menu ofour Award CMOS do not have their ownscreens. Rather, these simply have smalldialog boxes that pop up, usually with"are you sure?" type messages.

Load Fail-Safe/Optimized defaults keepsus from having to memorise all of those weird settings. Fail-Safe sets everythingto very simple settings-we occasionally use this setting when very low-levelproblems like freeze ups occur, and we have checked more obvious areas first.Optimized sets the CMOS to the best possible speed/stability for our system.We often use this one when we have tampered with the CMOS too much andneed to "put it back like it was!"

Many CMOS setup programs enable you to set a password in CMOS to forcethe user to enter a password every time the system boots. This CMOS passwordshows up at boot, long before Windows even starts to load.

Some CMOS setups enable you to create two passwords: one for boot andanother for accessing the CMOS setup program. This extra password just forentering CMOS setup. All CMOS setups provide some method to Save andExit and to Exit Without Saving. Use these as needed for your situation. Exitwithout Saving is particularly nice for those people who want to poke aroundthe CMOS but don't want to mess anything up.


Fig. 12.22 Advanced BIOS

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LAB EXERCISE 12.1 : Motherboard slot Identification and CMOSSettings

Objective: To be able identify the chipset and the form factor of themotherboard as well as be familiar with the different slots which are present on itand be familiar with the different CMOS settings.

Tasks:1. Identify the motherboard form factor for the motherboards given.2. Identify the socket no. of the processor, if the motherboard has a socket or

else identify the slot and what are the processors which are supported by thesocket or slot.

Buses/Slots Identification Devices that can be Connected

3. Check out the different expansion slots which are present on the motherboardand how they can be identified with the help of the foll reference table below.

4. Identify the chipset of your machine, which normally appears on the lower leftside of the screen. when you initially switch on the machine.

5. Check out the BIOS manufacturer and Enter the setup program dependingupon the function key to pressed.

6. Once inside the Setup, try changing the boot order sequencing i.e.if it is setto floppy earlier, then set it to hard disk or vice versa.

7. Set a system password to "cms" & while rebooting verify whether it isapplied or not.

8. Find out the latest mother board chip sets available in the Market during theconduction of this chapter.

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Floppy drives are used primarily for backups of small amounts of data, forbootable diagnostic disks, and for the creation of bootable emergency diskswith some versions of Windows. The 1.44MB floppy drive shown in Figure 13-1 and Figure 13-2 is found in some recent and virtually all older desktop andlaptop computers, although many recent computers no longer use floppydrives. The 1.44MB drive uses 3.5-inch double-sided high-density (DSHD)media, and also supports the 720KB 3.5-inch double-sided double-density(DSDD) media used by 3.5-inch drives produced in the 1980s. Some olderIBM systems used a 2.88MB DSED floppy drive, but were also compatible with1.44MB and 720KB floppy disks.

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Floppy Disk Drive

Figure 13-1 A typical 3.5-inch floppydisk drive.

Figure 13-1 shows the front and sides of a typical 3.5-inch floppy drive, andFigure 13-2 shows the data and power connectors used by 3.5-inch floppydrives.

In the following sections, you will learn about the different types of floppy diskdrives and media, and how drives are installed, configured in the BIOS, andmaintained


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Figure 13-2 The rear of a typical 3.5-inch drive before (left) and after (right) data and power cables are attached

Floppy Disk Types

Floppy drives use flexible magnetic media protected by a rigid plastic caseand a retractable shutter. There have been three different types of 3.5-inchfloppy disk media used over time, although only the 1.44MB floppy disk isused currently. Figure 13-3 compares the capacities and distinguishing marksof each disk type. Note that all 3.5-inch disks use the write-enable slider shownin Figure 13-3.

Table 13-2 helps you distinguish between different disk types in use today.

Disk Type Capacity Jacket Reinforced Write-Protect Media SensorHub

3.5-inch 720KB Rigid with N/A Open write- N/A

DSDD metal shutter protect slider

3.5-inch 1.44MB Rigid with N/A Open write- Opposite write-DSHD metal shutter protect slider protect slider

3.5-inch 2.88MB Rigid with N/A Open write- Offset fromDSED metal shutter protect slider protect slider

Of the disks pictured in Figure 13-3, only the 3.5-inch DSHD disk is commonlyused today. 1.44MB disks are often marked HD on their front and always havea media-sensing hole in the opposite corner from the write-enable/protectslider.


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Figure 13-3 A 3.5-inch 720KBfloppy disk (left) compared toa 1.44MB floppy disk (right),and a 2.88MB floppy disk(center).

3.5-inch media. The LS-120 SuperDisk uses 120MB media, and the LS-240SuperDisk can use 120MB or 240MB media. These drives usually plug intothe ATA/IDE (PATA) interface if internal, or the parallel or USB port if external.5.25-inch floppy drives were used before 3.5-inch drives became commonplace,but they have been obsolete for some years and are seldom used.

Floppy Disk Drive Hardware ConfigurationFloppy disk drive hardware configuration depends on several factors, including

• Correct CMOS configuration- The system's BIOS configuration screen musthave the correct drive selected for A: and B:.

• Correct cable positioning and attachment- The position of the drive(s) onthe cable determine which is A: and which is B:. If the cable is not orientedproperly, the drive will spin continuously and the LED on the front of thedrive will stay on.

The standard floppy disk drive interface uses a single IRQ and single I/O portaddress range, whether the interface is built in or on an expansion card:

• Floppy Drive IRQ: 6

• Floppy Drive I/O Port Address: 3F0-3F7h


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The standard floppy disk drive interface can support two drives: drive A: anddrive B:. However, some recent systems support only one floppy drive (A:). The34-pin floppy disk drive data cable has wires numbered 10 to 16 twisted inreverse between the connectors for drive A: and drive B:. The drive beyondthe twist is automatically designated as drive A:; the drive connected betweenthe twisted and the untwisted end of the cable (which connects to the floppycontroller) is automatically designated as drive B:.Figure 13-4 compares five-connector universal (3.5-inch/5.25-inch) andthreeconnector 3.5-inch floppy cables. (The cable connector to the floppycontroller is not visible in this photo.)

Figure 13-4 Two types offloppy drive cablescompared. On the left, acable designed for3.5-inch drives only; onthe right, a cable designedfor 3.5-inch and 5.25-inchdrives.

Floppy Disk Drive Physical Installation and RemovalTo install a 3.5-inch 1.44MB floppy disk drive as drive A:, follow these steps:Step 1. Select an empty 3.5-inch external drive bay; an external drive bay isa drive bay with a corresponding opening in the case.Step 2. Remove the dummy face plate from the case front.Step 3. For an ATX tower system, remove the left side panel (as seen from thefront). For a BTX tower system, remove the right side panel (as seenfrom the front). For a desktop system, remove the top.Step 4. If the 3.5-inch drive bay is a removable "cage," remove it from thesystem.This might involve pushing on a spring-loaded tab or removing a screw. Some


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drive bays pull straight out (as here), whereas others swing to one side.Step 5. Remove the floppy disk drive from its protective packaging. Test thescrews you intend to use to secure the drive and ensure they're properlythreaded and the correct length.Step 6. Check the bottom or rear panel of the drive for markings indicatingpin 1; if no markings are found, assume pin 1 is the pin closest to the powersupply connector.Step 7. Secure the drive to the drive bay with the screws supplied with the driveor with the computer (see Figure 13-5).Step 8. Replace the drive bay into the computer.Step 9. Attach the 34-pin connector at the end of the floppy disk drive datacablewith the twist to the data connector on the drive.Step 10. Run the other end of the floppy disk drive data cable through the drivebay into the interior of the computer. Then, connect it to the floppydisk drive interface on the motherboard or add-on card.Step 11. Attach the correct type of four-wire power cable to the drive. Youmight need to slide the drive part way into the drive bay to make theconnection.Step 12. Double check power and data cable keying before starting thecomputer.Step 13. Follow these steps in reverse to remove the drive from the system.

Floppy Drive BIOS ConfigurationFloppy disk drives cannot be detectedby the system; you must manuallyconfigure the floppy disk drive or floppydisk drives you add to the system.

Figure 13-5 A removable drive cage with theattachment screws for the floppy disk drive andhard drive. The opposite side of each drive isalso secured with screws (not shown).


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To configure the floppy disk drive in the ROM BIOS, follow these steps:Step 1. Verify the correct physical installation as listed previously.Step 2. Turn on the monitor and the computer.Step 3. Press the appropriate key(s) to start the BIOS configuration program.Step 4. Open the standard configuration menu.Step 5. Select Drive A: or the first floppy disk drive.Step 6. Use the appropriate keys to scroll through the choices; 3.5-inch 1.44MBis the correct choice for virtually all systems with an onboard floppydrive (see Figure 13-6).Step 7. No other changes are necessary, so save your changes and exit toreboot the system.If you only need a floppy drive for occasional use, you can connect an externalfloppy drive to the USB port. If you need to boot from an external floppy driveor need to load drivers from it during the installation of Windows, check thesystem BIOS setup program to verify that the drive is listed as a bootable device

Figure 13-6 Viewing floppy drive type options in the BIOS setup program of a typical system.


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Maintaining Floppy Disks, Data, and DrivesYou can protect the data on your floppy disks by following theserecommendations; most of these suggestions also apply to higher-capacitymagnetic removable media such as Zip, REV, and tape backups:

• Do not open the protective metal shutter on 3.5-inch disks or tape backups.

• Do not touch the magnetic media itself.

• Store disks away from sources of magnetism (CRT monitors, magnetizedtools, unshielded speakers, and unshielded cables) or heat.

• Open the sliding write-protect hole on 3.5-inch disks to prevent the contentsof the disk from being changed.

Floppy disk drives are a type of magnetic storage in which the read/write headsmake direct contact with the media. This is similar to the way that tape driveswork, and just like tape backup, music cassette, or VCR heads, a floppy diskdrive's read/write heads can become contaminated by dust, dirt, smoke, ormagnetic particles flaking off the disk's media surfaces. For this reason,periodic maintenance of floppy disk drives will help to avoid the need totroubleshoot drives that cannot reliably read or write data.

The following are some guidelines for cleaning a floppy disk drive:

• Approximately every six months, or more often in dirty or smoke-filledconditions, use a wet-type head-cleaning disk on the drive. These cleaningkits use a special cleaning floppy disk that contains cleaning media inplace of magnetic media, along with an alcohol-based cleaner. Add a fewdrops to the media inside the cleaning disk, slide it into the drive, andactivate the drive with a command such as DIR or by using WindowsExplorer; as the read/write heads move across the cleaning media, theyare cleaned. Allow the heads to dry for about an hour before using thedrive.

• Whenever you open a system for any type of maintenance or checkup,review the condition of the floppy disk drive(s). Use compressed air toremove fuzz or hair from the drive heads and check the mechanism forsmooth operation

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165


Hard DiskA hard disk drive is a sealed unit that a PC uses for nonvolatile data storage.Nonvolatile, or semi-permanent, storage means that the storage device retainsthe data even when no power is supplied to the computer.

Hard disks are used as a repository in which vast amounts of information canbe stored and unlike RAM, this information is permanent in that it is retainedeven after the computer is powered down. This is done using the principlesof magnetic storage, which is similar in principle to that used in retrieving andstoring information on conventional tapes. Hard disks allow data to be storedat far denser levels and can be accessed very quickly. Understanding theworking of a hard disk can be simplified by drawing a parallel to theconventional audio or videotape.

Because the hard disk drive is expected to retain data until deliberately erasedor overwritten, the hard drive is used to store crucial programming and data.As a result, when the hard disk fails, the consequences are usually very serious.

A hard disk drive contains rigid, disk-shaped platters, usually constructed ofaluminIum or glass.

In the hard disk, the magnetic material is layered on to an aluminium or glassplatter which is polished to mirror smoothness. In hard disk the head actually'flies' microns above the surface of the platter and is never really allowed totouch the surface of the hard disk. The platters of the hard disk can spin underthe head at rates of up to 3,000 inches per second translating into a speedof 225 Km/hr! The information on a hard disk is stored in extremely smallregions or magnetic domains that is made possible through the use of veryprecise control mechanisms that arrange the magnetic particles in platters thatelectronically correspond to 0s and 1s.

In hard disks available today, the drive platters spin at 5,400 RPM, 7,200 RPM,10,000 RPM or, in the new generation drives, upto 15,000 RPM. Consideringthe speeds at which the platters spin, if the heads come into contact with theplatters, there would be severe damage to the disk surface and consequently

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to the data stored. The arm that controls thehead is responsible for moving the head tothe correct location on the disk and is fab-ricated so as to be extremely light andmanoeuvrable. The arm on a typical drivecan move the head from the hub to theperimeter of the drive and back at rates ofup to 50 times per second. Nearly all oftoday's hard disks contain more than oneplatter, and a corresponding number of read-write heads that together decide the capac-ity of the hard disk. Many hard disks todaycan store 80GB per platter. This implies that

each platter holds 40GB per side and if it is to be used in an 80GB hard disk,then two read-write heads are used - one for each side of the platter. The samehard disk with one read-write head would go into the making of a 40GB harddisk. Similarly, if two platters were used, depending upon the number of read-write heads that are used, the hard disk could be fabricated as a 120GB (withthree read-write heads) or a 160GB hard disk (with 4 read-write heads).

INSIDE THE HARD DISK DRIVE :The Platter : The media is the hard metallic disk made of Aluminium andcoated with iron oxide which gives a typical rust brown look. Unlike the floppydisk drive, the media in the hard disk drive is permanently fixed to the drivemechanism, hence it is also called Fixed disk drive. Depending on the capacityof storing data, there could be more than one platter (disk). Usually 2,3,4, etc.are provided. Since both the sides of the disk platter is coated with themagnetic material, it provides additional storage space. This warranties theprovision for two R/W heads per platter to enable the storage of informationon both the surfaces. Thus, it can be presumed that for every platter in the drive,two heads are required. Eg : If there are 2 platters, 4 heads are provided and

for 3 platters, 6 heads and so on.

Similar to FDD’s, hard disk surface is also formed with concentriccircular paths of data storage called tracks and each track is sub-divided into sectors. The density of tracks on a hard disk is ofthe order of 300 - 1024 tracks (maximum) on one surface, whereas a floppy disk can have typically 40/80 tracks on one surface.The number of sectors/track is also higher than the floppy disk,i.e., 63 sectors/tracks against 9 or 15 sectors/tracks.

Read/Write Head : Just as in the case of floppy disk drives,


Bezel

Headac tuator

Head arm

Platter

Read/wr itehead

Fig. 14.1 Inside of the Harddisk drive.

PL AT T T E RS

PLATT TERS

HEAD 0

HEAD 1

HEAD 2

HEAD 3

SIDE 1

SIDE 2

SIDE 3

SIDE 0

SPIN DLE

SPINDLE MOTOR

Fig. 14.2 The platters andhead arrrangement in thehard disk drive.


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or for that matter, any magnetic recording device viz., audiotape, video tape, data recording devices etc. The HDD’s toouse a coil of winding to electrically induce magnetic flux onthe recording surface or medium. Similar coil is also usedto detect the existence of the magnetic flux on the medium.These coils form the Write and the Read mechanisms. Theassembly consisting of the R/W coils is called a head. Onehead assembly is provided for every recording surface.

It is noted that the recording media or the disk is divided intotracks and sectors. Also the fact remains that the disk isrotating at a constant speed of 7200/10,000 rpm. Considering

this, the R/W head assembly is mounted on a carriage device so that it canmove linearly to access any of the track spread over the entire disk surface.All the heads are mounted on one carriage assembly. This assumes the accessof same numbered tracks on all surfaces simultaneously i.e., head 0 on surface0 accesses the track 0 (of surface 1) & so on. The disk (recording) surface istreated as an array of dot positions, each of this is considered as a bit thatis set to the magnetic equivalent of 0 or 1. Since these dot positions are notprecisely determined, there is a need for marking the disk with synchronizationbits, matching with the recorded data. This is done during the formatting ofthe disk. Magnetic recording is basically analogous in form as in case of soundrecording in the audio tapes. The sync bytes on the timing tracks help indigitalizing this information during the data separation. The movement ofcarriage assembly to move from one track to another track is achieved bydriving it with a stepper motor or in some cases a voice coil mechanism. Thisis called head actuation.

Carriage Actuator : Carriage actuation in a FDD is done using a steppermotor. Accuracy is required in a low track density media like the FDD .Actuation in a HDD which is either done by the stepper motor or by the voicecoil, depending upon the capacity of the drive. A stepper motor moves in stepsrather than continuously. The stepper motor is mechanically linked to the headcarriage by a split steel band, coiled around the motor spindle. Sometimesthe rack and the pinion gear mechanism is also used. Usually each step ofthe motor moves the R/W head by one track position. If the head has to move,let us say, to track number 300, then the stepper motor must move 300 stepsin the required direction.

Voice coil actuator : Voice coil method of actuation is done usually in largecapacity drives with high reliability. The voice coil mechanism moves the headcarriage assembly by pure electro-magnetic force. The construction of this isanalogous to an audio speaker which uses a stationary magnet surrounded

GAP

PLATTER SURFACE

IRON CORE

Fig. 14.3 The read/writehead arrangement in the harddisk drive.


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by a voice-coil ( hence the name ) that is connected to thepaper cone. When the coil is energized, it moves causingthe cone to move thus producing sound. Typically in a harddisk voice coil, it is mounted on a track and surroundinga stationary magnet. Coil mechanism is connected to thehead carriage assembly. As the coil is energised it attractsor repels the stationary magnet causing the head carriageto move forward or backwards. This enables fast, quiet and

accurate operation when compared with the stepper motor. Since the movementin this mechanism is not of the pre-determined steps indicating a track position,some unique method is used to determine accurate access of a track. Thismethod involves in allocating one of the surfaces of one platter as dedicatedservo surface. This is done by the manufacturer. The tracks on this surface arerecorded with index signals to represent the cylinders. The head coil on thissurface can only detect these index signals & they cannot write. This head iscalled the servo head giving feedback to the servo circuitry, which determinesand controls the position of the head over each track thus enabling access toevery cylinder on the disk.

Hard Disk Spindle MotorThe spindle motor, also sometimes called the spindle shaft, is responsible forturning the hard disk platters, allowing the hard drive to operate. The spindlemotor is sort of a "work horse" of the hard disk. It's not flashy, but it must providestable, reliable and consistent turning power for thousands of hours of continuoususe, to allow the hard disk to function properly. In fact, many drive failures areactually failures with the spindle motor, not the data storage systems. For manyyears hard disks all spun at the same speed. In the interests of performance,manufacturers have been steadily ratcheting up their products' spin speedsover the last few years. These higher-speed spindles often have issues relatedto the amount of heat and vibration they generate. The increased performanceand also the new potential issues related to the spindle motor have given itrenewed attention in the last few years.

All PC hard disks use servo-controlled DC spindle motors. A servo system isa closed-loop feedback system; this is the exact same technology as is usedin modern voice coil actuators. In the case of the spindle motor, the feedbackfor the closed-loop system comes in the form of a speed sensor. This providesthe feedback information to the motor that allows it to spin at exactly the rightspeed. Increasing the speed at which the platters spin improves both positioningand transfer performance: the data can be read off the disk faster duringsequential operations, and rotational latency--the time that the heads mustwait for the correct sector number to come under the head--is also reduced,

Function Stepper motor Voice coil

Relative speed Slow FastTemperature sensitivity Yes NoPosition sensitivity Yes NoAuto head park No YesReliability / Accuracy Poor HighCost L o w High

Fig. 14.4 Comparisonbetween Stepper motor andvoice coil actuator.


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improving random operations. For this reason, there has been a push toincrease the speed of the spindle motor, and more than at any other time inthe past, hard disk spin speeds are changing rapidly.

This table shows the most common PC spindle speeds, their associatedaverage rotational latency, and their typical applications as of early 2000:

Spindle Speed Average Latency Typical Current Application(RPM) (Half Rotation) (ms)3,600 8.3 Former standard, now obsolete

4,200 7.1 Laptops4,500 6.7 IBM Microdrive, laptops

4,900 6.1 Laptops5,200 5.8 Obsolete

5,400 5.6 Low-end IDE/ATA, laptops7,200 4.2 High-end IDE/ATA, Low-end SCSI

10,000 3.0 High-end SCSI12,000 2.5 High-end SCSI

15,000 2.0 Top-of-the-line SCSI

Hard Disk GeometryGeometry determines where the drive stores data on the hard drive. Thegeometry for the particular hard drive describes a set of numbers that referto five special values: the heads, cylinders, sectors per track, write precompand landing zone.

HeadsThe number of heads for a specific hard drive describes, rather logically, thenumber of read/write heads used by the drive to store data. Every platter

requires two heads. If a hard drive has four platters,for eg., it would need eight heads.

CylindersA platter has two sides with concentric tracks. Twotracks the align exactly with each other (one on thebottom of the platter, and one on the top) form acylinder. If there are two or more platters, all pairsof tracks that line up with each other make up thecylinder. If there are three platters, for eg., eachcylinder has six tracks (three pairs). In other words,taken together, the tracks become a virtual cylinder.You can see the relationship between tracks andcylinders in Fig. 14.5.

The number of tracks per surface is identical to the number of cylinders;


Fig. 14.5 Relationshipbetween tracks andcylinders on a disk

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therefore, most manufacturers do not report the number of tracks, they reportthe number of cylinders. Although the two terms mean different things, peopleuse cylinder and track synonymously.

Sectors per TrackImagine cutting the hard drive like a birthday cake, slicing all the tracks intotens of thousands of small slivers. Each sliver is called a sector, and each sectorstores 512 bytes of data "sector" refers to the sliver when discussing thegeometry, but refers to the specific spot on a single track within that sliver whendiscussing the data capacity.

Cylinders, heads, and sectors/track combine to define the hard drive's geometry.In most cases, these three critical values are referred to as CHS. The importanceof these three values lies in the fact that the PC's BIOS needs to know the drive'sgeometry in order to know how to talk to the drive. A technician needed toenter these values into CMOS manually earlier. Today, every hard drive storesthe CHS information in the drive itself in an electronic format that enables theBIOS to query the drive automatically in order to determine these values.

Unlike the CHS values, the last two-write precomp and landing zone-no longerhave relevance in today's PCs; however, most CMOS setup utilities still supportthese two values.

Write Precompensation CylinderOlder hard drives had a real problem with the fact that sectors towards theinside of the drives were much smaller than sectors toward the outside. Tohandle this, an older drive would write data a little further apart once it gotto a particular cylinder. This cylinder was called the Write Precompensation(write precomp) cylinder, and the PC had to know which cylinder began thiswider spacing. Hard drives no longer have this problem, making the writeprecomp setting obsolete.

Landing ZoneOn older hard drives with stepper motors, the landing zone value designatedan unused cylinder as a "parking place" for the read/write heads. Old steppermotor hard drives needed to have the read/write heads parked before beingmoved in order to avoid accidental damage. Today's voice coil drives parkthemselves whenever they're not accessing data, automatically placing theread/write heads on the landing zone. As a result, the BIOS no longer needsthe landing zone geometry.

InterleavingA common operation when working with a hard disk is reading or writing anumber of sectors of information in sequence. After all, a sector only contains

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512 bytes of user data, and mostfiles are much larger than that.Let's assume that the sectors oneach track are numberedconsecutively, and say that wewant to read the first 10 sectors ofa given track on the hard disk.Under ideal conditions, thecontroller would read the firstsector, then immediately read thesecond, and so on, until all 10sectors had been read. Just likereading 10 words in a row in thissentence.

However, the physical sectors ona track are adjacent to each otherand not separated by very muchspace. Reading sectorsconsecutively requires a certain

amount of speed from the hard disk controller. The platters never stop spinning,and as soon as the controller is done reading all of sector 1, it has little timebefore the start of sector 2 is under the head. Many older controllers used withearly hard disks did not have sufficient processing capacity to be able to dothis. They would not be ready to read the second sector of the track until afterthe start of the second physical sector had already spun past the head, at whichpoint it would be too late.

If the controller is slow in this manner, and no compensation is made in thecontroller, the controller must wait for almost an entire revolution of the plattersbefore the start of sector 2 comes around and it can read it. Then, of course,when it tried to read sector 3, the same thing would happen, and anothercomplete rotation would be required. All this waiting around would killperformance: if a disk had 17 sectors per track, it would take 17 times as longto read those 10 sectors as it should have in the ideal case!

To address this problem, older controllers employed a function calledinterleaving, allowing the setting of a disk parameter called the interleavefactor. When interleaving is used, the sectors on a track are logically re-numbered so that they do not correspond to the physical sequence on the disk.The goal of this technique is to arrange the sectors so that their position onthe track matches the speed of the controller, to avoid the need for extra"rotations". Interleave is expressed as a ratio, "N:1", where "N" represents how

Fig. 14.6 Interleave ratio1:1,1:2,1:3.

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far away the second logical sector is from the first, how far the third is fromthe second, and so on.

An example is the easiest way to demonstrate this method. The standard forolder hard disks was 17 sectors per track. Using an interleave factor of 1:1,(Refer fig. 14.6) the sectors would be numbered 1, 2, 3, .. , 17, and the problemdescribed above with the controller not being ready in time to read sector 2would often occur for sequential reads. Instead, an interleave factor of 2:1could be used. With this arrangement, the sectors on a 17-sector track wouldbe numbered as follows: 1, 10, 2, 11, 3, 12, 4, 13, 5, 14, 6, 15, 7, 16, 8,17, 9. Using this interleave factor means that while sector 1 is being processed,sector 10 is passing under the read head, and so when the controller is ready,sector 2 is just arriving at the head. To read the entire track, two revolutionsof the platters are required. This is twice as long as the ideal case (1:1interleaving with a controller fast enough to handle it) but it is almost 90%better than what would result from using 1:1 interleaving with a controller thatis too slow (which would mean 17 rotations were required).

What if the controller was too slow for a 2:1 interleave? It might only be fastenough to read every third physical sector in sequence. If so, an interleave of3:1 could be used, with the sectors numbered as follows: 1, 7, 13, 2, 8, 14,3, 9, 15, 4, 10, 16, 5, 11, 17, 6, 12. Again here, this would reduce performancecompared to 2:1, if the controller was fast enough for 2:1, but it would greatlyimprove performance if the controller couldn't handle 2:1.

So this begs the question then: how do you know what interleave factor to use?Well, on older hard disks, the interleave factor was one parameter that hadto be tinkered with to maximize performance. Setting it too conservativelycaused the drive to not live up to its maximum potential, but setting it tooaggressively could result in severe performance hits due to extra revolutionsbeing needed. The perfect interleave setting depended on the speeds of thehard disk, the controller, and the system. Special utilities were written to allowthe analysis of the hard disk and controller, and would help determine theoptimal interleave setting. The interleave setting would be used when the drivewas low-level formatted, to set up the sector locations for each track.

On modern disk drives, the interleave setting is always 1:1. The spindle speedof a hard disk has increased from 3,600 RPM on the first hard disks, to today'sstandards of 5,400 to 10,000 RPM. An increase in speed of 50% to 177%. Thefaster spindle speed means that much less time for the controller to be readybefore the next physical sector comes under the head. However, look at whatprocessing power has done in the same time frame: CPUs have gone from4.77 MHz speeds to the environs of around 3-4 GHz; an increase of over20,000%! The speed of other chips in the PC and its peripherals have similarly

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gotten faster by many multiples.

As a result of this increase in speed in modern circuits, controller speed is nolonger an issue for current drives. There is in fact no way to set the interleavefor a modern drive; it is fixed at 1:1 and no other setting would be necessary.

Physical GeometryThe physical geometry of a hard disk is the actual physical number of heads,cylinders and sectors used by the disk. On older disks this is the only type ofgeometry that is ever used--the physical geometry and the geometry used bythe PC are one and the same. The original setup parameters in the systemBIOS are designed to support the geometries of these older drives. Classically,there are three figures that describe the geometry of a drive: the number ofcylinders on the drive ("C"), the number of heads on the drive ("H") and thenumber of sectors per track ("S"). Together they comprise the "CHS" method ofaddressing the hard disk.

At the time the PC BIOS interfaces to the hard disk were designed, hard diskswere simple. They had only a few hundred cylinders, a few heads and all hadthe same number of sectors in each track. Today's drives do not have simplegeometries and therefore do not have the same number of sectors for eachtrack, and they use defect mapping to remove bad sectors from use. As a result,their geometry can no longer be described using simple "CHS" terms. Thesedrives must be accessed using logical geometry figures, with the physicalgeometry hidden behind routines inside the drive controller.

Logical GeometryWhen you perform a drive parameter autodetection in your system BIOS setupor look in your new IDE/ATA hard disk's setup manual to see what the driveparameters are, you are seeing the logical geometry values that the hard diskmanufacturer has specified for the drive. Since newer drives use zoned bitrecording, wherein tracks are grouped into zones based on their distance fromthe center of the disk, and each zone is assigned a number of sectors per track,having ten or more values for sectors per track depending on which regionof the disk is being examined, it is not possible to set up the disk in the BIOSusing the physical geometry.

The BIOS routines for the original AT command set allowed a hard drive sizeonly upto 504 MB wherein a drive could have no more than 1024 cylinders,16 heads, and 63 sectors/track. Since the BIOS has a limit of 63 sectors pertrack, and all newer hard disks average more than 100 sectors per track therewould be a problem.

Older hard disks that had simple structures and low capacity did not need

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special logical geometry. Their physical and logical geometry was the same.

Newer drives cannot have their true geometries expressed using three simplenumbers. To get around this issue, for disks 8.4 GB or smaller, the BIOS is givenbogus parameters that give the approximate capacity of the disk, and the harddisk controller is given intelligence so that it can do automatic translationbetween the logical and physical geometry. The actual physical geometry istotally different, but the BIOS (and your system) need know nothing about this.Here's an example showing the difference between the physical and logicalgeometry for a sample drive, a 3.8 GB Quantum Fireball TM:

Specification Physical Geometry Logical GeometryRead/Write Heads 6 16Cylinders (Tracks per Surface) 6,810 7,480

Sectors Per Track 122 to 232 63

Total Sectors 7,539,840 7,539,840

If you install this drive, as far as the system is concerned, the disk has 16 headsand 63 sectors on every track, and the hard disk itself takes care of all the"dirty work" of translating requests to their real internal locations. The physicalgeometry is totally hidden from view. The fact that both geometries equate tothe same number of total sectors is not a coincidence. The purpose of thelogical geometry is to enable access to the entire disk using terms that the BIOScan handle. The logical geometry could theoretically end up with a smallernumber of sectors than the physical, but this would mean wasted space on thedisk. It can never specify more sectors than physically exist, of course.

LBA (Logical Block Addressing)Another way to get around the problem of complex internal geometry is tochange the way the drive is addressed completely. Instead of using the logicalgeometry numbers directly, most modern drives can be accessed using logicalblock addressing (LBA). With this method a totally different form of logical"geometry" is used: the sectors are just given a numerical sequence startingwith 0. Again, the drive just internally translates these sequential numbers intophysical sector locations. So the drive above would have sectors numberedfrom 0 to 7,539,839. This is just yet another way of providing access to thesame sectors.

Today's drives are over 8.4 GB in size and have therefore run into an importanthard disk capacity barrier: the 8.4 GB capacity barrier. The largest logicalparameters that can be used for accessing a standard IDE/ATA drive are 1,024cylinders, 256 heads, and 63 sectors. Since the ATA standard only allows amaximum of 16 for the number of heads, BIOS translation is used to reduce

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the number of heads and increase the number of cylinders in the specification.The practical result of all of this, is that the largest logical geometry numbersfor IDE/ATA drives are 16,383 cylinders, 16 heads and 63 sectors. This yieldsa maximum capacity of 8.4 GB.

INT13 ExtensionsDrives larger than 8.4 GB can no longer be accessed using regular BIOSroutines, and require extended Int 13h capabilities.

In 1994, Phoenix Technologies (the BIOS manufacturer) came up with a newset of BIOS commands called Interrupt 13 extensions (INT13). INT13 extensionsbreak the 8.4GB barrier by completely ignoring the CHS values and insteadfeeding the LBA a stream of "addressable sectors". A system with INT13extensions can handle drives upto 137GB. Most systems made since 1998 haveINT13 extension support.

There is no way to even represent their full capacity using regular IDE/ATAgeometry numbers. Therefore, these drives just specify 16,383 cylinders, 16heads and 63 sectors to the BIOS for compatibility. Then, access to the driveis performed directly by the Int 13h extension routines, and the logicalparameters are completely ignored. Here's how a modern drive, the 34.2 GBIBM Deskstar 34GXP (model DPTA-373420), looks:

Specification Physical Geometry Logical GeometryRead/Write Heads 10 16

Cylinders (Tracks per Surface 17,494 16383Sectors Per Track 272 to 452 63

Total Sectors 66,835,440 16,514,064

As you can see, the logical and physical geometries clearly have nothing todo with each other on drives this large, and even the total number of sectorsis wrong in the logical geometry. The drive must be accessed directly by anoperating system supporting Int 13h BIOS extensions to see the whole drive,or drive overlay software used. If the drive is addressed using conventionalgeometry parameters, it will be limited in capacity to only 8.4 GB, which inthe case of this drive would mean wasting over 75% of its capacity. Since theycannot have their true capacity expressed in terms of even logical geometry,all large modern drives are accessed using logical block addressing.

The translation between logical and physical geometry is the lowest level oftranslation that occurs when using a modern hard disk.

Hard-Drive TypesThe number of heads, cylinders, sectors/track, write precomp, and landingzone determine how the hard-drive controller accesses the physical hard drive.

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Each number must be correct if the hard drive is to function properly. WhenIBM created the first CMOS on the 286 AT, they believed that the five differentgeometry numbers would be too complicated for normal users to configure.For simplicity, IBM established 15 present combinations of hard-drive geometries,called hard-drive types. So instead of worrying about five different variables,users could simply enter a hard-drive type into the CMOS. The concept of typesdid make configuring the hard drive geometry in CMOS much easier.

Initially, this worked well, but a problem arose. Note the capacities of theoriginal 15 hard-drive types. They are small. If a manufacturer came up witha new, larger hard-drive type, the list would have to be expanded. At first, IBMdid exactly that, eventually expanding the list to 37 different types.

BIOS designers soon realized that adding to the list every time a manufacturercreated a new hard-drive geometry was not practical, so IBM simply stoppedusing drives that required unique geometries and stopped adding drive types.The other BIOS makers continued to add types until they got to around 45different types. At that time, AMI created a new "user" type. With this type,instead of selecting a special type, users could enter in the five geometry valuesmanually. This provided more flexibility for hard-drive installation.

AutodetectionBefore roughly 1994, you had to use the hard-drive type to install a hard drive.This manual installation process was always a bit of a problem. You had tohave the proper CHS values, you had to be sure to type them in correctly, andyou had to store these values in case your CMOS was accidentally erased.Today, all PCs can set the CMOS properly by using autodetection. All IDE/EIDEdrives have their CHS values stored inside of them. Autodetection simplymeans that the CMOS asks the drive for those stored values and automaticallyupdates the CMOS. There are two common ways to perform autodetection.First, most CMOS setup utilities have a hard-drive type called "Auto". By settingthe hard-drive type to Auto, the CMOS automatically updates itself every timethe computer is started.

After selecting the Autodetection option, most CMOS setup utilities will lookfor any hard drive installed on the system.

Hard Disk Interfaces and ConfigurationThe interface that the hard disk uses to connect to the rest of the PC is in someways as important as the characteristics of the hard disk itself. The interfaceis the communication channel over which all the data flows that is read fromor written to the hard disk. The interface can be a major limiting factor in systemperformance. The choice of interface also has an essential impact on systemconfiguration, compatibility, upgradability and other factors.

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Not all interfaces support the same devices. Depending on what devices andmodels you are trying to use, one interface may make much more sense thananother. Fortunately, the market has evolved so that there are really only twomain interfaces used today for hard disks: IDE/ATA and its variants, and SCSIand its variants. The fact that there are only two standards in common usemeans that each of them supports a large number and variety of devices. Inaddition, this makes it easier for software support to be made universal, andthis is no longer much of an issue when using these mainstream interfaces.

IDE/ATA tends in general to support a larger number of hard disk models, andalso optical drives and other devices, especially economy models. This is notdue to any particular technical advantages that IDE/ATA possesses over SCSI.It's simply a function of IDE/ATA being more popular than SCSI, and thereforeoffering manufacturers more of a target market than SCSI does. SCSI tendsto have better support for high-end devices and also more device types.

The most important consideration is the hardware and software cost forimplementing the interface. What this often boils down to is whether or notsupport for the interface is already included in a given system. For example,the presence of IDE/ATA controllers on all modern motherboards makes thisinterface less expensive for most people than going with SCSI, which wouldrequire the addition of a SCSI host adapter. Similarly, USB has been aroundfor years, but is only becoming popular now that almost all new systems havebuilt-in support for it, both hardware and software.

There are two hard disk interfaces that were used in the early days of the PC,in the 1980s. Both of the interfaces described here were made obsolete by IDE/ATA and SCSI, which offered significant advantages over them without imposingany real cost.

Enhanced Small Device Interface (ESDI)The first attempt at improving the original ST-506/ST-412 hard disk interfacewas the Enhanced Small Device Interface or ESDI. ESDI was developed in themid-1980s by a consortium of hard disk manufacturers led by Maxtor. It movedsome drive controller functions to the hard disk from the controller card,eliminating some of the reliability problems associated with its predecessor.It had a maximum theoretical bandwidth of 24 Mbits/second (fairly fast forthose days), though in practice the limit was about half of that. In the late 1980sESDI suffered under competition from IDE/ATA in the mainstream market andfrom SCSI in the high-end market, both of which offered significant advantagesover ESDI, such as simpler configuration, lower cost and improved performance.

Integrated Drive Electronics / AT Attachment (IDE/ATA) InterfaceThe most popular interface used in modern hard disks-by far-is the one most

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commonly known as IDE. This interface is also known by a truly staggeringvariety of other names such as ATA, ATA/ATAPI, EIDE, ATA-2, Fast ATA, ATA-3,Ultra ATA, Ultra DMA and many more as well. IDE/ATA hard disks are usedon the vast majority of modern PCs, and offer excellent performance atrelatively low cost. They are challenged only by SCSI, which has certainadvantages and disadvantages when the two interfaces are compared. Forstarters, the most commonly used name for this interface, "IDE" is a misnomeritself. The "proper" name for the IDE interface is AT Attachment, or ATA. Thisname is not as commonly used, for historical reasons.

IDE tells you quite a bit about its history. IDE drives were the first ones topopularize integrating the logic controller onto the hard disk itself. This changecorrected many of the problems that had been associated with hard disks upto that point, such as poor signal integrity, complexity and the need for everycontroller to be "generically" capable of dealing with any hard disk.

The very first hard disks to have integrated controllers weren't technically usingthe IDE/ATA interface as we currently know it. They were in fact so-called"hardcards", which were designed and sold by the "Plus Development" divisionof Quantum. These devices were simply 3.5" hard disks that were mounteddirectly to a controller card that plugged into an ISA expansion slot. It didn'ttake long until manufacturers realized that there was really no reason to keepthe hard disk physically on the controller at all. They decided to put thecontroller on the bottom of the hard disk and move the entire hard disk andcontroller assembly to a regular drive bay. The connection to the system buswas maintained through the use of a cable that ran either directly to a systembus slot, or to a small interfacing card that plugged into a system bus slot.In many ways, then, these drives were connected directly to the ISA system bus.The official name for the interface, "AT Attachment", reflects this, as the IBM PC/AT was the first PC to use the now-standard 16-bit ISA bus.

Compaq began selling PCs with integrated hard disks using Western Digitalcontrollers starting with their IBM-compatible Deskpro 386 in 1986. Othermanufacturers quickly caught on to the idea and the IDE concept grew inpopularity rather quickly. As system and hard disk performance improved, theslow speed of the ISA bus became an issue, so interface cards--often calledcontroller cards were created for the higher speed VESA local bus, and thenthe PCI bus. Today, all modern PCs have their IDE/ATA interface attacheddirectly to the PCI bus.

The next evolution of how IDE/ATA drives interface to the system occurred whenit became obvious that every PC was going to have a hard disk, and it wastherefore silly to waste an expansion slot even on a hard disk interface card.Chipset manufacturers began integrating IDE/ATA hard disk controllers into

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their chipsets, so that instead of connecting the drives to a controller card, theywere connected directly to the motherboard. With this change, integration ofthe interface was complete, with all the logic either on the motherboard, orthe hard disk itself. This is the technique that is used today.

The IDE/ATA interface is fairly straight-forward. The connection between thesystem and the hard disks is 16 bits wide, so two bytes of data are passedat a time between the system and any hard disk. This is true regardless of thewidth of the system bus, and persists even today with high-performanceenhancements like Ultra DMA. Two drives are supported on each IDE/ATAchannel, with special signalling used to ensure that commands sent for onedrive don't interfere with the other.

The original ATA standard defined features that were appropriate for early IDE/ATA hard disks. However, it was not well-suited to support the growing size andperformance needs of a newer breed of hard disks. These disks required fastertransfer rates and support for enhanced features.

ATA (Advanced Technology Attachment)The first formal standard defining the AT Attachment interface was submittedto ANSI for approval in 1990. The original ATA standard defined features thatwere appropriate for early IDE/ATA hard disks. However, it was not well-suitedto support the growing size and performance needs of a newer breed of harddisks. These disks required faster transfer rates and support for enhancedfeatures. Several companies were impatient, and started the industry down theroad to incompatible proprietary extensions to the original ATA standard.Western Digital, meanwhile, created "Enhanced IDE" or "EIDE", a somewhatdifferent ATA feature set expansion. EIDE included powerful new features suchas higher capacities, support of non-hard drive storage devices, for a maximumof four ATA devices and substantially improved throughput.

SFF-8020 / ATA Packet Interface (ATAPI)Originally, the IDE/ATA interface was designed to work only with hard disks.CD-ROMs and tape drives used either proprietary interfaces (often implementedon sound cards), the floppy disk interface (which is slow and cumbersome) orSCSI. Unfortunately, because of how the ATA command structure works, it wasn'tpossible to simply put non-hard-disk devices on the IDE channel and expectthem to work. Therefore, a special protocol was developed called the ATAttachment Packet Interface or ATAPI. The ATAPI standard is used for deviceslike optical, tape and removable storage drives. It enables them to plug intothe standard IDE cable used by IDE/ATA hard disks, and be configured asmaster or slave, etc. just like a hard disk would be. When you see a CD-ROMor other non-hard-disk peripheral advertised as being an "IDE device" or

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working with IDE, it is really using the ATAPI protocol.

A special ATAPI driver is used to communicate with ATAPI devices. This drivermust be loaded into memory before the device can be accessed (most neweroperating systems support ATAPI internally and in essence, load their owndrivers for the interface). The actual transfers over the channel use regular PIOor DMA modes, just like hard disks, although support for the various modesdiffers much more widely by device than it does for hard disks. For the mostpart, ATAPI devices will coexist with IDE/ATA devices and from the user'sperspective, they behave as if they are regular IDE/ATA hard disks on thechannel. Newer BIOSes will even allow booting from ATAPI CD-ROM drives.

Small Computer Systems Interface (SCSI)The other popular hard disk interface used in PCs today is the Small ComputerSystems Interface, abbreviated SCSI and pronounced "skuzzy". SCSI is a muchmore advanced interface than its chief competitor, IDE/ATA, and has severaladvantages over IDE that make it preferable for many situations, usually inhigher-end machines. It is far less commonly used than IDE/ATA due to itshigher cost and the fact that its advantages are not useful for the typical homeor business desktop user.

SATA InterfaceSATA stands for Serial Advanced Technology Attachment. It is a new high-speed

serial interface for mass storage that will eventuallyreplace Parallel ATA (PATA), the current mass storageattachment standard.

It has the advantages of increased bandwidth 150-300Mb/s depending upon the standard used as comparedto 100 Mb/s for PATA, thinner, longer cables, lowervoltages and no jumpers. The fig. 14.7 show the SATAinterface connections and the connectors.

iSCSIIn computing, iSCSI, is an abbreviation of Internet Small Computer SystemInterface, an Internet Protocol (IP)-based storage networking standard forlinking data storage facilities. By carrying SCSI commands over IP networks,iSCSI is used to facilitate data transfers over intranets and to manage storageover long distances. iSCSI can be used to transmit data over local areanetworks (LANs), wide area networks (WANs), or the Internet and can enablelocation-independent data storage and retrieval. The protocol allows clients(called initiators) to send data to SCSI storage devices (targets) on remote

Fig. 14.7 SATA InterfaceConnecter


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servers. It is a Storage Area Network (SAN) protocol, allowing organizationsto consolidate storage into data center storage arrays while providing hosts(such as database and web servers) with the illusion of locally-attached disks.

IDE/ATA Transfer Modes and ProtocolsSince performance is of utmost concern when using a hard disk, the differenttransfer modes and protocols that a drive (and interface) supports are veryimportant. Most of the advances in newer IDE/ATA standards are orientedaround creating faster ways of moving data between the hard disk and thePC system. Since the IDE/ATA interface is in essence a communication channel,support for a given transfer mode or protocol requires support from the deviceson both ends of the channel. This means that both the hard disk and the systemchipset and BIOS must support the mode in question.

Interestingly, despite the obvious advantages of bus mastering DMA, the useof bus-mastering multiword DMA mode 2, which had a transfer rate of 16.7MB/s never really caught on. The other important reason was the poor stateof support for the technology for the first couple of years. Thus initially DMAdidn't offer much incentive to make the switch from the PIO mode which offeredthe same speed as the DMA mode.

IDE/ATA ControllersEvery PC system that uses the IDE/ATA interface has at least one IDE/ATAcontroller. Now, as soon as you read that, a question probably formed in yourmind: isn't the drive controller built into the drive in IDE, and in fact, wasn'tthat the whole point of how the name "IDE" came about? And you're absolutelyright. Unfortunately, naming conventions in the PC world often leave much tobe desired. A device that resides within the system and interfaces with aperipheral device is often commonly called a "controller", even though this isn'ttechnically accurate.

So what exactly does this so-called IDE/ATA controller do, if not control thehard disk? Well, it acts as the middleman between the hard disk's internalcontroller and the rest of the system. As such, its less common name is the moreaccurate one: IDE/ATA interface controller. The controller (whatever its name)is what manages the flow of information over the IDE/ATA channels, allowingthe hard disk to talk to the rest of the PC.

The data pathway over which information flows in the IDE/ATA interface iscalled a channel. Each IDE channel is capable of communicating with up totwo IDE/ATA devices It is theoretically possible to configure and use as manyas four (or even more) different IDE/ATA interface channels on a modern PC.There is nothing inherently different in concept between these channels, althoughthere can be a difference in terms of how they are implemented.

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Single, Master and Slave Drives and JumperingIDE/ATA devices of course each contain their own integrated controllers, andso in order to maintain order on the channel, it is necessary to have some wayof differentiating between the two devices. This is done by giving each devicea designation as either master or slave, and then having the controller addresscommands and data to either one or the other. The drive that is the target ofthe command responds to it, and the other one ignores the command,remaining silent.

The only practical difference between master and slave is that the PC considersthe master "first" and the slave "second" in general terms. For example, DOS/Windows will assign drive letters to the master drive before the slave drive.If you have a master and slave on the primary IDE channel and each has onlyone regular, primary partition, the master will be "C:" and the slave "D:". Thismeans that the master drive (on the primary channel) is the one that is booted,and not the slave.

Devices are designated as master or slave using jumpers, small connectorsthat fit over pairs of pins to program the drive through hardware. Eachmanufacturer uses a different combination of jumpers for specifying whetherits drive is master or slave on the channel, though they are all similar. Somemanufacturers put this information right on the top label of the drive itself, whilemany do not; it sometimes takes some hunting around to find where the jumperpins are on the drive even once you know how the jumpers are supposed togo. The manufacturers now are better about this than they have been in thepast, and jumpering information is always available in the manual of the harddisk, or by checking the manufacturer's web site and searching for the modelnumber.

Configuration Using Cable SelectAn alternative to the standard master/slave jumpering system used in the vastmajority of PCs is the use of the cable select system. As the name implies, withthis system the cable--or more correctly, which connector on the cable a deviceis attached to--determines which device is master and which is slave. The goalof cable select is to eliminate having to set master and slave jumpers, allowingsimpler configuration.

To use cable select, both devices on the channel are set to the "cable select"(CS) setting, usually by a special jumper. Then, a special cable is used. Thiscable is very similar in most respects to the regular IDE/ATA cable, except forthe CSEL signal. CSEL is carried on wire 28 of the standard IDE/ATA cable,and is grounded at the host's connector (the one that attaches to the motherboardor controller). On a cable select cable, one of the connectors (the "master

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connector") has pin 28 connected through to the cable, but the other (the "slaveconnector") has an open circuit on that pin (no connection).

Hard Disk Logical Structures and File SystemsThe hard disk is, of course, a medium for storing information. Hard disks growin size every year, and as they get larger, using them in an efficient way becomesmore difficult. The file system is the general name given to the logical structuresand software routines used to control access to the storage on a hard disksystem. Operating systems use different ways of organizing and controllingaccess to data on the hard disk, and this choice is basically independent ofthe specific hardware being used-the same hard disk can be arranged in manydifferent ways, and even multiple ways in different areas of the same disk. Theinformation in this section in fact straddles the fine line between hardware andsoftware, a line which gets more and more blurry every year.

The nature of the logical structures on the hard disk has an important influenceon the performance, reliability, expandability and compatibility of your storagesubsystem. The operating system is the large, relatively complex, low-levelpiece of software that interfaces your hardware to the software applicationsyou want to run. The operating system you use is closely related to the filesystem that manages your hard disk data. The reason is a simple one: differentoperating systems use different file systems. Some are designed specificallyto work with more than one, for compatibility reasons; others work only withtheir own file system.

PC File SystemsMost people are familiar with only the most common file system family (FATand its variants) which are used on most PC-platform machines. However, thereare in fact many different types of file systems in use by different operatingsystems for PC hardware. Many PC users actually employ more than one typeof file system, to handle different tasks.

File Allocation Table File System (FAT, FAT12, FAT16)The most common file system in the PC world is actually a family of file systems.The basic name for this file system is FAT; the name comes from one of themain logical structures that the file system uses: the file allocation table. Thisfile system is the one that was used by DOS on the first IBM PCs, and it becamethe standard for the PCs that followed. Today, most PCs still use a variant ofthe basic FAT file system created for those early machines over two decadesago.FAT in ConceptThe base storage area for hard drives is a sector, with each sector storing upto512 bytes of data. If an operating system stores a file smaller than 512 bytes

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in a sector, the rest of the sector goes to waste. One accepts this waste becausemost files are far larger than 512 bytes. So what happens when an operatingsystem stores a file larger than 512 bytes? The operating system needs amethod to fill one sector, find another that's unused, and fill it, continuing tofill sectors until the file is completely stored. Once the operating system storesa file, it must remember which sectors hold that file, so that file can be retrievedlater.

FAT32 (32-bit FAT)As hard disks continued to increase in size through the 1990s, the limitationsof the FAT16 and VFAT file systems began to become obvious. The use of largecluster sizes led to a significant amount of wasted hard disk space (slack).Eventually, hard disk manufacturers started to create drives so large that FAT16could not be used to format a whole drive in a single partition. PC makerscomplained that FAT16 was unwieldy for modern machines.

To correct this situation, Microsoft created FAT32. This newest FAT variant isan enhancement of the FAT/VFAT file system (even though the "V" was droppedfrom the name, FAT32 is based more on VFAT than FAT). It is named FAT32because it uses 32-bit numbers to represent clusters, instead of the 16-bitnumbers used by FAT16. FAT32 was created primarily to solve the twoproblems mentioned above. It allows single partitions of very large size to becreated, where FAT16 was limited to partitions of about 2 GB. FAT32 supportspartitions up to 2 terabytes. It also saves wasted space due to slack whencompared to FAT16 partitions, because it uses much smaller cluster sizes thanFAT16 does.

FAT32 was first introduced in Windows 95's OEM Service Release 2, and wasoriginally available only in later versions of Windows 95 when purchased froma hardware manufacturer. FAT32 support was later included in Windows 98,Windows ME and Windows 2000 as well.

New Technology File System (NTFS)When Microsoft created Windows NT, it built the operating system pretty muchfrom scratch--it was based on certain existing concepts, of course, but wastotally different from older Microsoft operating systems. One of the keyelements of NT's architecture was the file system created especially for theoperating system, called the New Technology File System or NTFS.

NTFS is a much more complex and capable file system than any of the FATfamily of file systems. It was designed with the corporate and businessenvironment in mind; it is built for networking and with the goals of security,reliability and efficiency. It includes many features, including file-by-filecompression, full permission control and attribute settings, support for very

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large files, and transaction-based operation. It also does not have the problemswith cluster sizes and hard disk size limitations that FAT does, and has otherperformance-enhancing features such as RAID support. Its most significantdrawbacks are increased complexity, and less compatibility with other operatingsystems compared to FAT.

The following tables compare general and technical information for a numberof file systems

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Master Boot Record (MBR)When you turn on your PC, the processor has to begin processing. However,your system memory is empty, and the processor doesn't have anything toexecute, or really even know where it is. To ensure that the PC can always bootregardless of which BIOS is in the machine, chip makers and BIOS manufacturersarrange so that the processor, once turned on, always starts executing at thesame place, FFFF0h.

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In a similar manner, every hard disk must have a consistent "starting point"

where key information is stored about the disk, such as how many partitions

it has, what sort of partitions they are, etc. There also needs to be somewhere

that the BIOS can load the initial boot program that starts the process of

loading the operating system. The place where this information is stored is

called the master boot record (MBR). It is also sometimes called the master

boot sector.

The master boot record is always located at cylinder 0, head 0, and sector1, the first sector on the disk. This is the consistent "starting point" that the diskalways uses. When the BIOS boots the machine, it will look here for instructionsand information on how to boot the disk and load the operating system. Themaster boot record contains the following structures:

• Master Partition Table: This small table contains the descriptions of thepartitions that are contained on the hard disk. There is only room in themaster partition table for the information describing four partitions.Therefore, a hard disk can have only four true partitions, also calledprimary partitions. Any additional partitions are logical partitions that arelinked to one of the primary partitions. One of the partitions is marked asactive, indicating that it is the one that the computer should use for bootingup.

• Master Boot Code: The master boot record contains the small initial bootprogram that the BIOS loads and executes to start the boot process. Thisprogram eventually transfers control to the boot program stored onwhichever partition is used for booting the PC.

Due to the great importance of the information stored in the master bootrecord, if it ever becomes damaged or corrupted in some way, serious dataloss can be--in fact, often will be--the result. Since the master boot code is thefirst program executed when you turn on your PC, this is a favourite place forvirus writers to target.

Partition TypesA hard drive may have up to four partitions. These partitions divide into oneof two types: primary and extended. Each type of partition performs differentfunctions and you create these partitions based on the needs of the particularPC system.

Primary PartitionsPrimary partitions store the OS(s). If you want to boot from a hard drive, it musthave a primary partition. Therefore, the MBR must check the partition tablefor a primary partition (Fig. 14.9). In Windows 9x and 2000, the primary

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partition is always C:, and you cannot change.

A hard drive can have up to four primary partitions, but in the DOS/Windows9x world, the built-in partitioning program, called FDISK, only enables oneprimary partition on the drive.

Active PartitionIf a hard drive stores multiple primary partitions, each with a valid operatingsystem, how does the system know which one to boot? That's where the conceptof active partition comes into play. For a primary partition to boot, you mustset it as the active partition. Only one primary partition may be "active" at atime. The MBR looks for a primary partition set to "active".

If you partition a new hard disk and create a primary DOS partition using thestandard DOS utility FDISK, but forget to set the primary partition active, theBIOS will be unable to boot the operating system. This usually results in anerror message like "No boot device available".

Boot ManagersThere are programs specifically designed for the task of booting and they areusually called Boot Managers or boot loaders. What a boot manager doesis insert itself into the very beginning of the boot process, sometimes by settingup a special boot manager partition and making itself the active partition.When you boot up the PC, the code in this partition runs. It analyzes the primarypartitions on the disk and then presents a menu to you and asks whichoperating system you want to use. Whichever one you select, it marks as active,and then continues the boot process from there. Other methods may also beused to accomplish the same general objectives.

Boot managers are in many ways indispensable when working with multipleoperating systems. However, you still want to take care when using one, sinceit does modify the disk at a very low level. Some boot managers require theirown, dedicated partitions to hold their own code, which complicates slightlythe setup of the disk. There are now a variety of different boot managerproducts on the market.

Extended PartitionYour hard drive may or may not have the other partition type-an extendedpartition. Extended partitions are not bootable and one hard drive can onlyhave one extended partition. If a hard drive has an extended partition, it takesup one of the areas in the partition map for the primary partitions. You mayonly have up to three primary partitions on a drive with an extended partition.

Extended partitions are completely optional; you do not have to create anextended partition on a hard drive. So, if you can't boot to an extended partition

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and your hard drive doesn't need an extendedpartition, why would you want to create one? Firstof all, many systems do not use extended partitions.Some hard drives are partitioned as one big primarypartition-nothing wrong with that. We use extendedpartitions when we find a situation where we wantto chop a drive into multiple drive letters.

The beauty of an extended partition is in the wayit handles drive letters. When you create a primarypartition, it gets a drive letter and that's it. But whenyou create an extended partition, it does notautomatically get a drive letter. Instead, you divide

the extended partition into "logical drives". An extended partition may have asmany logical drives as you wish, limited only by the letters of the alphabetfor Windows 9x systems, enabling a maximum of 24 logical drives on onesystem (remember that A: and B: are reserved for floppy drives). You may turnan extended partition into one logical drive or into multiple logical drives,whatever suits you. You may set the size of each logical drive to any size youwant.

All of this flexibility creates a little problem, especially for people new topartitioning. Because a newly created extended partition doesn't yet havelogical drives, working with extended partitions always requires two steps: first,make the extended partition, then create logical drives within that extendedpartition. This two steps process often confuses a new person. They forget tocreate logical drives in the extended partition and wonder why they don't seeany new drive letters in My Computer when they finish partitioning.

PartitioningPartitioning the hard disk is the act of dividing it into pieces; into logicalvolumes. This is one of the first things done when setting up a new hard disk,because partitions are one of the major disk structures that define how the diskis laid out.

In order to use the space in a hard disk, it must be partitioned. Partitioningis the process of dividing the hard disk's space into chunks, so they can beprepared for use, or even dedicated to different uses. Even if the entire diskis intended to be left in one piece, it must be partitioned so that the operatingsystem knows that it is intended to be left in one piece. There are many differentconsiderations that go into deciding how to partition a hard disk.

The choice of how the disk is partitioned is important because partition sizehas an important impact on both performance and on how efficiently the disk's

Fig. 14.9 Master Boot Recordcontaining the Master BootCode and Master PartitionTable


Master BootCode

Master PartitionTable

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space is utilized. Even the matter of "efficiency" has several different facets,depending on one's priorities.

The rules that determine how partitions are used were set down very early inthe original design of the PC, and have remained virtually unchanged sincethat time. Recall that when the PC was first invented there was only (really) onetype of file system. Still, it was envisioned that in the future, multiple operatingsystems and/or file systems might be wanted on a single machine. Therefore,provision was made in the partitioning scheme to allow for several differentpartitions. The rules that govern partition setup are as follows:

• A maximum of four partitions can be placed on any hard disk. These aresometimes called primary partitions. The limitation of four is one that isimposed on the system by the way that the master boot record is structured.

• Only one partition may be designated, at any given time, as active. Thatpartition will be used for booting the system.

• DOS (and the operating systems that depend on it for booting, whichincludes all consumer Windows operating systems) will only recognize theactive primary partition. Any other primary partitions will be ignored.

• One of the four partitions may be designated as an extended DOSpartition. This partition may then be subdivided into multiple logicalpartitions. This is the way that two or more logical DOS volumes can beplaced on a single hard disk.

This is somewhat confusing, so let's take a look at some examples of systems,to show you how this scheme is used:

• Single Partition Windows PC: Many PCs have all of their disk space madeinto a single partition, and use one of the FAT file systems. Such a machinewould have just a single FAT primary partition on it, and nothing else.

• Multiple Partition Windows PC: To use more than one partition at a timeon a DOS/Windows system, two partitions are used. One is a regular DOSprimary partition (which becomes the "C:" drive). The other is the extendedDOS partition. Within the extended DOS partition, all the other logicaldrives are created. So a drive with four logical drive letters would have thefirst (C:) be the active primary partition, and the other three (D:, E: andF:) would be logicals within the extended DOS partition.

• Multiple Operating System PC: A system with multiple operating systemscould use one primary partition for each of up to four different file systems.

If you want, you can also combine multiple partitions with multiple operatingsystems. For example, you could have a primary DOS partition, an extendedDOS partition, and a Linux partition. Such setups are far less common thanthe simpler examples above.

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TroubleshootingPatience is said to be a virtue, and with hard disks that is true to a tee. Basically,if you make a mistake while using FDISK or formatting a drive and catch itbefore you install an operating system and several hundred megabytes ofsoftware, you can pretty easily recover. If you don't find out the following aresome of the tips.

• If your computer won't boot from your hard drive, run FDISK again andcheck to see that the partition you have your OS installed on is set as theactive partition.

• If FDISK reports a disk size that isn't true, your BIOS may be incorrectlyidentifying your hard drive. Run your BIOS setup program and confirm thatthe size is correct, and try running FDISK again.

• An older BIOS may not recognize newer hard disks, especially those over2GB or 8.4GB (depending on the system age). If this is the case, you shouldupdate your BIOS if possible. You may have to use special softwareprovided by your hard disk manufacturer to fool your BIOS into recognizingthe disk.

• No access FORMAT? That may not be a problem. If you are planning toinstall Windows on the new hard disk, you may not need to bother withformatting the drive. Simply boot from your Windows CD (if your systemallows you to boot from a CD-check the Boot Sequence settings in yourBIOS) and let the SETUP program format the disk for you.

• Formatting a disk does not automatically make it bootable. If you've startedthe PC with a startup floppy made with Windows 95/98, use the /S switchwith the FORMAT command (FORMAT C: /S) to copy the system filesneeded to boot along with the formatting operation.

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LAB EXERCISES : Different Operations on Hard Disk Drive

Objective: To be familiar with the different parts of a Hard disk drive and partitionand format a hard disk drive using the "fdisk" and the "format" command as well asusing third party utilities such as PQMagic, Norton Ghost and DE in DOS.

Lab Exercise 14.1: Identification and simple troubleshootingTasks:1. Open a scrap hard disk and identify the different components such as the number

of platters, the head actuator, spindle motor, voice actuator etc.2. Connect the hard disk to the hard disk controller on the motherboard, configuring

it properly by jumpers to master and check whether the machine has detectedthe hard disk or else use the autodetect option in the PC's Setup program.

3. Use another hard disk and connect the two hard disks in such a manner that boththe hard disks use the same controller on the motherboard, and are both configuredas masters using jumpers and verify whether they are getting detected using theSetup program.

Create a partition in Windows with DiskpartUsing Diskpart to partition your disk is very beneficial for increasing the I/O performanceof hard disks newly added to a RAID array. The documentation for many serverapplications, such as Microsoft Exchange Server, actually goes so far as to recommendthat you should use Diskpart to create your Primary or Extended partitions. (A primarypartition can be used as the system partition; an Extended Partition can only be usedfor additional logical drive assignments.)To create a partition:

1. At a command prompt, type: Diskpart.exe

2. At the DISKPART prompt, type: LIST DISK (Lists disks found. Make note of thedrive number you wish to manipulate.)

3. At the DISKPART prompt, type: Select Disk 1 (This selects the disk; make sureto type in the disk number from step 2.)

4. At the DISKPART prompt, type: CREATE PARTITION PRIMARY SIZE=10000

(Change the word PRIMARY to EXTENDED to create an extended partition.) (If youdo not set a size (in MB), such as the above example for 10 GB, then all availablespace on the disk will be used for the partition.) (Seriously consider adding thefollowing option to the end of the above command if you are using RAID (especiallyRAID 5) to improve disk I/O performance: ALIGN=64)

5. At the DISKPART prompt, type: ASSIGN LETTER=D (Choose a drive letter notalready being used.)

6. At the DISKPART prompt, type: Exit

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.

7. Use the Command Prompt format command, Disk Administrator or any disk formatutility to format the drive (typically using NTFS, of course).

Extend a partition in Windows with Diskpart. When it comes to adding space to a partitionor volume, this method is superior to configuring Dynamic Disks. Dynamic Diskextensions only concatenate the newly added space, menaing they merely add the diskspace to the "end" of the original partition without restriping the data.Concatenation isolates performance within each partition and does not offer faulttolerance when the partition is configured in a RAID array. Diskpart allows you torestripe your existing data. This is truly beneficial when the partition is set up in a RAIDarray, because the existing partition data is spread out across all the drives in the array,rather than just adding new space to the end (like Disk Administrator).Microsoft's "official" position is that that you cannot use Diskpart to extend your systemor boot partitionNote: If you try it or any other method, make sure you have a full backup.

To extend a partition:

1. Verify that contiguous free space is available on the same drive and that free spaceis next to the partition you intend on extending (with no partitions in between).


3. At the DISKPART prompt, type: Select Disk 1 (Selects the disk.)

4. At the DISKPART prompt, type: Select Volume 1 (Selects the volume.)

5. At the DISKPART prompt, type: Extend Size=10000 (If you do not set a size, suchas the above example for 10 GB, then all available space on the disk will be used.)


Note: It is not necessary, but I normally reboot the server to make sure all is well froma startup standpoint.

To delete a partition in Windows with Diskpart: (Note: You cannot delete an active systemor boot partition or a partition with an active page file.)


2. At the DISKPART prompt, type: Select Disk 1

3. At the DISKPART prompt, type: Select Partition 1

4. At the DISKPART prompt, type: DELETE partition


To wiping (or zero) a disk:

This operation deletes all data on the disk


2. At the DISKPART prompt, type: Select Disk 1

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3. At the DISKPART prompt, type: CLEAN ALL (The CLEAN ALL commandremoves all partition and volume information from the hard drive being focused on.)


Final note: Here are four important things to keep in mind regarding Diskpart.

" Do not use DISKPART until you have fully backed up the hard disk you aremanipulating

" Do not use DISKPART on dynamic disks

" Check with your disk vendor before using Diskpart

" Install the Windows Resource Kit to get the Diskpart utility

Lab Exercise 14.3: Using PQ Magic on a Hard DiskTasks:10. Now using the "PQMagic" utility, which is a third party software, try merging the

two logical partitions which were created by using Fdisk utility.

PQ MagicThe PQ Magic utility when executed presents the main menu, which can only beoperated in the DOS mode, if it's an older version of PQMagic in which case onewill have to use the keyboard shortcuts to select the appropriate options.To merge a particular partition with another,• Select the partition which is the original partition which has to be merged and then• Select the option of Operations in which lies the option of Merging the partition

which is to be selected.• It then prompts us the different options whether the target or the second partition

should appear as a folder in the original selected partition or vice versa as wellas prompting us to name the folder.

• The operation once confirmed will only be applied if the Apply option is selectedwhich then applies the changes to be made on the partitions and after confirmationagain, the changes will be applied after restarting the machine.

Lab Exercise 14.4: Backing Up and Restoring the MBR of the Hard disk.Tasks:10. With the help of the Disk Editor (DE) utility take a backup of the MBR of the

Hard Disk on the floppy disc and after making minor changes in the MBR contents,check whether the hard disk is able to boot. If not, then try using the backed upcopy on the floppy disk ie. copy it back unto the MBR and then check whetherthe Hard disk is able to boot from it.

Disk Editor (DE)The Disk Editor or DE is a DOS based utility which when run will present the mainmenu showing all the files present in the Floppy disk as well as all the operations which

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can be performed.To take a backup of the MBR or Partition Table• Select the option of Object to change from the floppy disk to the hard disk drive.• Again, select Object option in which is present the Partition Table option to select

the Partition Table of the hard disk to Back Up.• Select the option for Edit in which there is a Mark option to select the data to

be selected for Backing Up.• To back up the data, Select the option in Edit to Copy to back up the selected

data.• Select the destination, where the data is to be copied by selecting the option of

Tools and then the option of Write to and then the option to a File• It then prompts for a location where the seleted data is to be copied

e.g.a:\MYBACKUP which then prompts for confirmation which when confirmedproceeds with the writing.

Now making Minor Changes in the MBR & verifying whether it is Booting• Making changes on MBR is the easiest step, which now involves just inserting

any data on the MBR of the hard disk and quitting which prompts whether thechanges made should be Written or Discard for which Write option should beselected.

Once DE is quit and the machine is restarted, the machine tries to boot from the Harddisk but it won't proceed just blinking with a cursor sign on the top left tof the screen.To recover the data i.e.MBR or Partition Table from the Floppy disk• To recover the MBR or Partition Table information, Run the DE utility which opens

as mentioned in step I earlier showing the contents of the floppy. Now to recoverselect the Object option in which there is a File option to select a particular filei.e.the backup copy of the MBR in the Floppy Disk.

• Once the contents of the file are shown, select the contents of the file to be copiedby going to Edit and then selecting the Mark option and then selecting data tobe copied.

• Now to copy the selected data contents, go to the Edit option and then selectthe Copy option for the marked contents to be copied.

Now to go to the MBR of the hard disk• Select the Object option and go to the Drive which when selected opens a small

box showing the different drives. Now Select the C: drive and select the driveType to Physical Disks and select OK which then opens and shows the locationsof the hard disk.

• Now select the Object option again and go to the Partition Table option whichthen opens just the MBR or Partition Table only whereas in the previous step itused to open the entire contents of the Hard disk.

• To copy the backed up file contents back to the MBR, then go to the Edit optionthen select the Paste over option which then replaces the contents of the MBR

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with the contents of the Backuped file.• Now, try booting from the Hard disk which should recover you from a corrupted

MBR problem back to the previous state before the problem.

Lab Exercise 14.5: Using Norton Ghost for Imaging of a Hard diskTasks:11. Using the Norton Ghost Utility try making an image of a partition of hard disk

onto another hard disk.

Norton GhostThe Ghost utility, when executed first presents the version no. as well the person towhom it is registered and then it presents the main menu which will give the optionsfor the different operations performed by it.To make an image of a Partition of a Hard disk,• Select the option for Local and then• Select the option to perform a Partition to Partition imaging which when selected• It then prompts to select a Source drive, where the operation is to be performed.• It then prompts for the source partition, which is to be imaged• It prompts for the destination drive, then• It prompts for the destination partition where it is to be imaged to.• It then again prompts for the confirmation whether to proceed with the copy and

when confirmed it performs the copy. After performing the clone it then promptsfor a restart of the machine for the changes to take effect.

** It should be noted however that the source partition and destination partition sizesshould be the same to perform the clone**

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Compact Disks- Read Only Memory or CD-ROMs as they are popularly known- have almost captured the market. For the last few years, the growing softwareindustry has made available a lot of new software. These software are veryintensive and capable of offering a lot of features as a result of which theyare very large. Most of these software are available on CDs.

CDs are gaining fast popularity due to their storage capabilities. Unlike harddisks, floppy disks and other magnetic media, CDs (Compact discs) areoptically readable. Magnetic media can be used only until the magnetism inthe media lasts; this normally is about 5 years. Certain external factors likemoisture or other magnetic fields contribute in reducing this time. The CDRshave an advantage here. Except physical damage there is nothing much thatcan affect it and therefore the longetivity of any optical media is much greaterwhen compared to any other media.

The most promising development in the optical area is that in the near futureCD-RW (compact disc rewritable) or DVD+RW (DVD+rewritable) will likelyreplace the venerable floppy disk as the de facto standard interchangeable,transportable drive and media of choice for PCs.

Most new systems today include a CD-RW drive, and even though a floppydrive is also included with most systems, it is rarely used except for runningtests; running diagnostics; or doing basic system maintenance, disk formatting,preparation for OS installation, or configuration.

CD-ROMsCD-ROM, or compact disc read-only memory, is an optical read-only storage

medium based on the original CD-DA (digital audio) format first developed

for audio CDs. Other formats, such as CD-R (CD recordable) and CD-RW (CD-

rewritable), are expanding the compact disc's capabilities by making it writable.

Additionally, new technologies such as DVD (digital versatile disc) are making

it possible to store more data than ever on the same size disc.

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CD-ROM is a read-only optical storagemedium capable of holding up to 74 or80 minutes of high fidelity audio(depending on the disc used), or up to682MB (74-minute disc) or 737MB (80-minute disc) of data, or somecombination of the two, on one side

(only the bottom is used) of a 120mm (4.72-inch) diameter, 1.2mm (0.047inches) thick plastic disc. CD-ROM has exactly the same form factor (physicalshape and layout) of the familiar CD-DA audio compact disc and can, in fact,be inserted in a normal audio player. It usually isn't playable, though, becausethe player reads the subcode information for the track, which indicates thatit is data and not audio.

Accessing data from a CD-ROM using a computer is quite a bit faster thanfrom a floppy disk but slower than a modern hard drive. The term CD-ROMrefers to both the discs themselves and the drive that reads them.

Two main types of recordable CD drives and discs are available, called CD-R (recordable) and CD-RW (rewritable). Because all CD-RW drives can alsofunction as CD-R drives, and the prices of CD-R and RW drives are similar,virtually all drives sold today are CD-RW. Those drives can work with eitherCD-R or CD-RW discs. In addition, because the CD-RW discs are 1.5-4 timesmore expensive than CD-R discs, only half as fast (or less) as CD-R discs, andwon't work in all CD audio or CD-ROM drives, people usually write to CD-R media in their CD-RW drives.

CD-ROM TechnologyIn 1979, the Philips and Sony corporations joined forces to co-produce theCD-DA (Compact Disc-Digital Audio) standard and identical in appearanceto CD-DAs is the CD-ROMs which store data instead of (or in addition to) audio.

A CD is made of a polycarbonate wafer, 120mm in diameter and 1.2mm thick,with a 15mm hole in the centre. This wafer base is stamped or molded witha single physical track in a spiral configuration starting from the inside of thedisc and spiraling outward. The track has a pitch, or spiral separation, of 1.6microns (millionths of a meter, or thousandths of a millimetre).

When viewed from the reading side (the bottom), the disc rotates counter-clockwise. If you examined the spiral track under a microscope, you would seethat along the track are raised bumps, called pits, and flat areas between thepits, called lands. It seems strange to call a raised bump a pit, but that isbecause when the discs are pressed, the stamper works from the top side. So,from that perspective, the pits are actually depressions made in the plastic.

Fig. 15.1 Different layers ofDisc

Printed LabelAcrylic Protective CoatingReflective Aluminium LayerMolded Plastic Disk Basi

Pits (raised) and Lands (flat)

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The laser used to read the disc would pass right through the clear plastic, sothe stamped surface is coated with a reflective layer of metal (usually aluminium)to make it reflective. Then, the aluminium is coated with a thin protective layerof acrylic lacquer, and finally a label or printing is added.

Reading Operation from CD-ROMReading the information back is a matter of bouncing a low-powered laserbeam off the reflective layer in the disc. The laser shines a focused beam onthe underside of the disc, and a photosensitive receptor detects when the lightis reflected back. When the light hits a land (flat spot) on the track, the lightis reflected back; however, when the light hits a pit (raised bump), no light isreflected.

As the disc rotates over the laser and receptor, the laser shines continuouslywhile the receptor sees what is essentially a pattern of flashing light as the laserpasses over pits and lands. Each time the laser passes over the edge of a pit,the light seen by the receptor changes in state from being reflected to notreflected or vice versa. Each change in state of reflection caused by crossingthe edge of a pit is translated into a 1 bit digitally. Microprocessors in the drivetranslate the light/dark and dark/light (pit edge) transitions into 1 bits, translateareas with no transitions into 0 bits, and then translate the bit patterns intoactual data or sound.

The individual pits on a CD are 0.125 microns deep and 0.6 microns wide(1 micron equals one millionth of a meter). Both the pits and lands vary inlength from about 0.9 microns at their shortest to about 3.3 microns at theirlongest (see Fig. 15.2).

The pit height above the land is especially critical as it relates to the wavelengthof the laser light used when reading the disc.

The read laser in a CD drive is a 780nm (nanometer) wavelength laser of about1 milliwatt in power. The polycarbonate plastic used in the disc has a refractive©CMS INSTITUTE 2012

Fig. 15.2 Pit and land geometry on a CD.


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index of 1.55, so light travels through the plastic 1.55 times more slowly thanthrough the air around it. Because the frequency of the light passing throughthe plastic remains the same, this has the effect of shortening the wavelengthinside the plastic by the same factor. Therefore, the 780nm light waves are nowcompressed to 780/1.55 = 500nm. One quarter of 500nm is 125nm, whichis 0.125 microns-the specified height of the pit.

Drive Mechanical Operation:

CD-ROM drives operate in the following manner (Refer fig. 15.3):

1. The laser diode emits a low-energy infrared beamtoward a reflecting mirror.

2. The servo motor, oncommand from themicroprocessor, positionsthe beam onto the correcttrack on the CD-ROM bymoving the reflect ingmirror.

3. When the beam hits the disc,its refracted light is gathered

and focused through the first lens beneath the platter, bounced off themirror, and sent toward the beam splitter.

4. The beam splitter directs the returning laser light toward another focusinglens.

5. The last lens directs the light beam to a photo detector that converts thelight into electric impulses.

6. These incoming impulses are decoded by the microprocessor and sentalong to the host computer as data.

CD Drive SpeedCDs originally were designed to record audio, the speed at which the drivereads the data had to be constant. To maintain this constant flow, CD-ROMdata is recorded using a technique called constant linear velocity (CLV). Thismeans that the track (and thus the data) is always moving past the read laserat the same speed, which originally was defined as 1.3 meters per second.The track is spiral that is wound more tightly near the centre of the disc andthe disc must spin at various rates to maintain the same track linear speed.In other words, to maintain a CLV, the disk must spin more quickly when readingthe inner track area and more slowly when reading the outer track area. The

Fig. 15.3 CD ROM Mechanicalassembly



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speed of rotation in a 1x drive (1.3 meters per second is considered 1x speed)varies from 540rpm when reading the start (inner part) of the track down to212rpm when reading the end (outer part) of the track. In the quest for greaterperformance, drive manufacturers began increasing the speeds of their drivesby making them spin more quickly.A drive that spins twice as fast was called a 2x drive, one that spins four timesfaster was called 4x, and so on. At higher speeds than this, it became difficultto build motors that could change speeds (spin up or down) as quickly asnecessary when data was read from different parts of the disc. Because of this,most drives rated faster than 12x spin the disc at a fixed rotational, rather thanlinear speed. This is termed constant angular velocity (CAV) because theangular velocity (or rotational speed) is what remains a constant. CAV drivesare also generally quieter than CLV drives because the motors don't have totry to accelerate or decelerate as quickly. CD-ROM drives have been availablein speeds from 1x up to 56x and beyond.

What is 'x' on CD drivesThe transfer rate of compact disc system is a direct function of the speed atwhich the disc itself spins. Increasing the data transfer require higher rotationspeeds. Consequently today's CD-ROM players operate much faster than theoriginal spin rate of audio CD players. The speeds are usually expressed asa multiple of the original audio CD data transfer rate (150 Kb/sec). For eg.,1x, 2x, 4x, 48x, 52x.

CD-ROM File SystemsManufacturers of early CD-ROM discs required their own custom software toread the discs. This is because the early specification for CD-ROM details onlyhow data sectors-rather than audio sectors-can be stored on a disc, and didnot cover the file systems or deal with how data should be stored in files andhow these should be formatted for use by PCs with different operating systems.Obviously, non-interchangeable file formats presented an obstacle to theindustry wide compatibility for CD-ROM applications.

In 1985-1986, several companies got together and published the High Sierrafile format specification, which finally enabled CD-ROMs for PCs to beuniversally readable. That was the first industry standard CD-ROM file systemthat made CD-ROMs universally usable in PCs. Several file systems are usedon CDs now which are as follows:

_ High Sierra

_ ISO 9660 (based on High Sierra)

_ Joliet

_ UDF (Universal Disk Format)


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High SierraIn 1985, representatives from TMS, DEC, Microsoft, Hitachi, LaserData, Sony,Apple, Philips, 3M, Video Tools, Reference Technology, and Xebec met at whatwas then called the High Sierra Hotel and Casino in Lake Tahoe, Nevada, tocreate a common logical format and file structure for CD-ROMs. In 1986, theyjointly published this standard as the "Working Paper for Information Processing:Volume and File Structure of CD-ROM Optical Discs for Information Exchange(1986)." This standard was subsequently referred to as the High Sierra format.This agreement enabled all drives using the appropriate driver (such asMSCDEX.EXE supplied by Microsoft with DOS) to read all High Sierra formatdiscs, opening the way for the mass production and acceptance of CD-ROMsoftware publishing.The High Sierra format was submitted to the International Organization forStandardization (ISO), and two years later (in 1988) and with several enhance-ments and changes it was republished as the ISO 9660 standard.

ISO 9660

The ISO 9660 standard enabled full cross compatibility among differentcomputer and operating systems. ISO 9660 was released in 1988 and wasbased on the work done by the High Sierra group. ISO 9660 has three levelsof interchange that dictate the features that can be used to ensure compatibilitywith different systems. ISO 9660 Level 1 is the lowest common denominatorof all CD file systems and is capable of being read by almost every computerplatform, including Unix and Macintosh. The downside of this file system is thatit is very limited with respect to file names and directories. Level 2 interchangerules have the same limitations as Level 1, except that the filename andextension can be up to 30 characters long (both added together, not includingthe . separator). Finally, Level 3 interchange rules are the same as Level 2except that files don't have to be contiguous.

The ISO 9660 data starts at 2 seconds and 16 sectors into the disc, which isalso known as logical sector16 of track one.

This data identifies the location of the volume area-where theactual data is stored. The system area also lists the directories inthis volume as the volume table of contents (VTOC), with pointersor addresses to various named areas, as illustrated in fig 15.4.

CD's system area also contains direct addresses of the files withinthe subdirectories, allowing the CD to seek specific sector locationson the spiral data track. Because the CD data is all on one longspiral track, when speaking of tracks in the context of a CD, we're

actually talking about sectors or segments of data along that spiral.Fig. 15.4 Logical sector16 oftrack one.



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JolietJoliet is an extension of the ISO 9660 standard developed by Microsoft foruse with Windows 95 and later. Joliet enables CDs to be recorded usingfilenames up to 64 characters long, including spaces and other characters fromthe Unicode international character set. Joliet also preserves an 8.3 alias forthose programs that can't use the longer filenames.

Universal Disk FormatUDF is a relatively new file system created by the Optical Storage TechnologyAssociation (OSTA) as an industry-standard format for use on optical mediasuch as CD-ROM and DVD. UDF has several advantages over the ISO 9660file system used by standard CD-ROMs but is most noted because it is designedto work with packet writing, a technique for writing small amounts of data toa CD-R/RW disc, treating it much like a standard magnetic drive. The UDFfile system allows long filenames up to 255 characters per name. There havebeen several versions of UDF, with most packet-writing software using UDF 1.5or later. Packet-writing software such as DirectCD from Roxio writes in the UDFfile system.

Interface TypeThe drive's interface is the physical connection of the drive to the PC's expansionbus.

The following types of interfaces are available for attaching a CD-ROM, CD-R, or CD-RW drive to your system:

i) ATA/ATAPI (AT Attachment/AT Attachment Packet Interface)

ii) Parallel port

iii) SCSI/ASPI (Small Computer System Interface/Advanced SCSI ProgrammingInterface)

iv) USB port

ATA/ATAPI:The ATA/ATAPI (AT Attachment/AT Attachment Packet Interface) is an extensionof the same ATA (AT Attachment) interface most computers use to connect totheir hard disk drives. ATA is sometimes also referred to as IDE (Integrated DriveElectronics). ATAPI is an industry-standard ATA ATA/ATAPI is an extension of thesame ATA interface most computers use to connect to their hard disk drives.ATA is sometimes also referred to as IDE (Integrated Drive Electronics). ATAPIis an industry-standard ATA interface used for CD/DVD and other drives. Thisenables drive manufacturers to take their high-end CD/DVD drive productsand quickly adapt them to the ATA interface. This also enables the ATA drivesto remain compatible with the MSCDEX (Microsoft CD-ROM Extensions) that


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provide a software interface with DOS. With Windows 9x and later, the CD-ROM extensions are contained in the CD file system (CDFS) VxD (virtual device)driver.

ATA/ATAPI drives are sometimes also called enhanced IDE (EIDE) drivesbecause this is an extension of the original IDE (technically the ATA) interface.

Parallel Port:One can install some CD-ROM drives simply by connecting a cable to the PC'sparallel port and loading the appropriate software. Although parallel portdrives have been available for some time now, USB has for the most partreplaced the parallel port for this type of use.

SCSI/ASPISCSI (pronounced scuzzy), or the Small Computer System Interface, is a namegiven to a special interface bus that allows many types of peripherals tocommunicate. A standard software interface called ASPI (Advanced SCSIProgramming Interface) enables CD-ROM drives (and other SCSI peripherals)to communicate with the SCSI host adapter installed in the computer. SCSIoffers the greatest flexibility and performance of the interfaces available forCD-ROM drives and can be used to connect many other types of peripheralsto your system as well.

USB InterfaceUSB (Universal Serial Bus) has proven to be extremely flexible and has beenused for everything from keyboards and joysticks to CD/DVD drives fromseveral vendors. USB 1.1 and earlier drives provide read and write transferrates that match the fastest rates possible with IEEE-1284 parallel ports, withread rates on typical 6x models ranging from 1,145KB/sec to 1,200KB/sec.USB 2.0 provides a transfer rate up to 60MB/sec, which is 40 times faster thanUSB 1.1 and yet fully backward compatible.

Media TypesWritable CDs:Although the CD originally was conceived as a read-only device, these daysone easily can create their own data and audio CDs. By purchasing CD-R orCD-RW discs and drives, you can record (or burn) your own CDs. This enablesyou to store large amounts of data at a cost that is lower than most otherremovable, random-access mediums.

In CD-R media, after you fill a CD-R with data, it is permanently stored andcan't be erased. The write-once limitation makes this type of disc less than idealfor system backups or other purposes in which it would be preferable to reusethe same media over and over. However, because of the low cost of CD-R


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media, you might find that making permanent backups to essentially disposableCD-R discs is as economically feasible as tape or other media. CD-RW discscan be reused up to 1,000 times, making them suitable for almost any typeof data storage task. When first introduced, there were many CD-R-only drives;however, today most recordable CD drives are both CD-R and CD-RW in one.The following sections examine these two standards and how you can use themfor your own data storage needs.

CD-ROnce recorded, CD-R discs can be played back or read in any standard CD-ROM drive. CD-R discs are useful for archival storage and creating master CDs,which can be duplicated for distribution within a company. CD-Rs functionusing the same principle as standard CD-ROMs, by bouncing laser light offthe disc and tracking the changes in reflectivity when pit/land and land/pitboundaries are encountered.

To record on a CD-R disc, a laser beam of the same wavelength (780nm) asis normally used to read the disc, but with 10 times the power, is used to heatup the dye. The laser is fired in a pulsed fashion at the top of the ridge (groove),heating the layer of organic dye to between 482° and 572°F (250°-300°C).This temperature literally burns the organic dye, causing it to become opaque.When read, this prevents the light from passing through the dye layer to thegold and reflecting back, having the same effect of cancelling the laserreflection that an actual raised pit would on a normal stamped CD.

All CD-R drives can work with the standard 650MiB (682MB) CD-R media(equal to 74 minutes of recorded music), as well as the higher-capacity 700MB(737MB) CD-R blanks (equal to 80 minutes of recorded music). The 80-minutediscs cost only about 2 cents more than the 74-minute discs, so most wouldfigure why not purchase only the higher-capacity media? Although the extra55MB of storage can be useful and the cost difference is negligible, the 80-minute discs can actually be harder to read on older CD-ROM and CD-DAdrives, especially car audio units. This is because to get the extra 55MB/6minutes of capacity, the spiral track is wound a little more tightly, making thema bit more difficult read.

CD-RWBeginning in early 1996, an industry consortium that included Ricoh, Philips,Sony, Yamaha, Hewlett-Packard, and Mitsubishi Chemical Corporationannounced the CD-RW format. The design was largely led by Ricoh, and theywere the first manufacturer to introduce a CD-RW drive in May of 1996. It wasthe MP6200S, which was a 2/2/6 (2x record, 2x rewrite, 6x read) rated unit.

Since that time, CD-RW drives have pretty much replaced CD-R-only drives


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in the market today, mainly because CD-RW drives are fully backward

compatible with CD-R drives and can read and write the same CD-R media

with the same capabilities. So, a CD-RW drive can also function as a CD-R

drive. CD-RW discs can be burned or written to just like CD-Rs; the main

difference is that they can be erased and reburned again and again. They are

very useful for prototyping a disc that will then be duplicated in less expensive

CD-R or even stamped CDs for distribution. They can be rewritten at least

1,000 times or more. Additionally, with packet-writing software, they can even

be treated like a giant floppy disk, where you can simply drag and drop or

copy and delete files at will. This makes CD-RW a viable technology for system

backups, file archiving, and virtually any other data storage task.

Besides the CD-RW media being rewritable and costing a bit more, they alsoare writable at about half (or less) the speed of CD-R discs. This is becausethe laser needs more time to operate on a particular spot on the disk whenwriting. They also have a lower reflectivity, which limits readability in olderdrives. Many standard CD-ROM and CD-R drives can't read CD-RWs. However,MultiRead capability is now found in virtually all CD-ROM drives of 24x speedor above, enabling them to read CD-RWs without problems.

Recording SoftwareAnother difficulty with CD-R/RW devices is that they require special softwareto write them. Although most cartridge drives and other removable mediamount as standard devices in the system and can be accessed exactly like ahard drive, the CD-R/RW drive uses special CD-ROM burning software to writeto the disc. This software handles the differences between how data is storedon a CD and how it is stored on a hard drive.

The software assembles the directory information, burns it onto the CD, openseach file on the CD, and copies the data directly from the original source. Nerois an example of such software.

Nero IntroductionIn 1989 a process was developed with which a CD can be directly written bymeans of a laser beam. The way for the self-creation of CDs was thus opened.

With the passage of time, the self-creation of CDs to meet individual needshas been made easy and economically feasible thanks to improved hardwareand practical software.

Nero - Burning ROM makes it possible for you to easily and quickly createyour own CDs due to its user-friendly interface and optimized processes.

Components for CD-Recording using NeroAs the minimal configuration for all Windows operating systems, you must


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have: A PC with a 486 processor orhigher and speed of at least 33 Mhzand a minimum of 8 MB RAM.

The PC must have a CD-ROM drive inorder to install Nero. If your CD-Recorder is recognized as a CD-ROMdrive when running with Windows, youmay also use the recorder. Up to now,Windows 95/98 has supported all ofthe drivers which are required for this.

After you have successfully installedNero, you can begin your first job with

the recording software.

You will find the default installation for the program under

START > Programs > Nero - Burning Rom.

Open Nero by clicking on it in the Start Menu.

The following illustration shows the options window for a New Compilation,which is the default window after Nero is started.

In a brief summary, the entire process for the creation of a CD may bedescribed in the following steps:

1. Creating a Compilation. In the Compilation, you determine which files willbe written on the CD.

The next two steps are for the only purpose of avoiding a possible bufferunderrun.

2. Determining Write Speed, also called the Speed test. This test is where themaximum possible write speed is defined. If a slower speed is measuredin the Speed test than provided by the current setting, the speed setting iscorrespondingly reduced. This test should be performed before everysimulation - or before the burn process, when there is no simulation.

3. Simulation of the Write Procedure: Here, the data of the compilation aretransferred to the CD-recorder, but the laser beam does not write the dataonto the CD. In this way it is determined whether you can expect everythingto run without problems during the burn process.

4. Burn process (Write process). You simply make sure a recordable CD iscorrectly inserted and then press the Write button, provided of course thewrite speed test and simulation were successful.

Basic Process of BurningWith Nero, the creation of a CD-ROM or an Audio CD is relatively simple.


Fig. 15.5 New Compilationdialog box.


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First, you'll need to decide which files should be written onto the CD. Thenyou can give your undivided attention to the compilation. A compilation iscreated with Nero by the drag and drop method. Here, you'll select the fileswhich you want from the File Browser and then drag them with the mouse intothe compilation window. There, you can arrange your files in any way you wishor even insert new folders. The advantage here is that this arrangement doesnot have any influence on the physical file structure on the hard drive.

After the compilation is arranged the way you want it to be, you should runthe speed test. This test checks the access speed to the hard drive, or to thepartition where the files which you want to be written are located. Dependingon the results of this test, a speed for the simulation will be recommended.The simulation which will now follow (and it should always follow!) assumesthis test result. By doing this, errors which might otherwise occur during the burnprocess may be detected and corrected. After a successful simulation, you canbe relatively confident that the compilation you have created can also bewritten. The burn process itself takes place as the last step.

Creating a New CompilationIn the New Compilation dialog box, click on the CD-ROM compilation type(it doesn't matter which property sheet is currently activated). Leave all of thedefault options as they are. Then, in the upper right of the same window, clickon the New button.

The Compilation window will open. This window consists of two panes. In theleft window, replace the file name NEW (in the upper left next to the CD icon)with HELLO.

In the right window, you will see the Nero file browser. The selection of the datawhich you want to write onto the CD is very simple with the browser. For yourfirst attempt to write a CD, select the file "Hello.txt" from the file browser in thedirectory [Drive name]:\Programs\ahead\Nero (if you have accepted thesuggested target directory during installation) and drag it into the left compilationwindow. Then activate it by clicking on it somewhere.

Now save the compilation by clicking on the floppy disk icon in the toolbar.The Save window will open. Type in the file name HELLO and then activatethe Save button. Your first compilation file is now complete.

Determining Maximum Write SpeedClick on the icon for Write CD in the toolbar. The Write CD window is displayedwith the Burn property sheet. The boxes for Determine Maximum Speed andSimulate are already selected in this window. Click on the Write selection boxat this time. You may leave all of the other options with their default settings.Confirm your selection by clicking on the Write button.


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In the fig. 15.6, you see the Write CDdialog box with the Burn property sheetand the selected options.

As the first step, Nero will nowdetermine the maximum possible writespeed and then transfer this value intothe Write Speed field.

Simulation of the WriteProcedureThe execution of this step was alreadyset by the previous selection of theSimulate box. Nero now simulates the

burn process in order to test whether the actual burn process will also runwithout any problems. Nero will inform you when the simulation has ended.With many recorders, the CD will be ejected. This means that, depending onthe recorder, it might be necessary to either re-insert the caddy or to close theCD drawer.

Burn Process (Write Process)You have already been prompted above to select the Write control box. Bydoing this, the burn process is performed immediately after the simulation.Nero will now begin the entire writing procedure with all of the preselectedphases.

During this process, a status window is opened (as shown in fig. 15.7) whichprovides you with different information during writing. The current compilationis displayed in the upper pane of the window. The phase which is running andits result is shown in the center pane. Below this, you will see a progress display

for each process.

The end of the writing process is indicated by aninformation box which indicates the successfulend of the burn process.

Terms Related to CD BurningTracksData items on a CD are not stored in concentriccircles, as one might at first think.

They are rather arranged in an extended spiral-shaped line whose origin is at the center of the CD.The line runs from the inside to the outside. Thosesections on the spiral on which data items are


Fig. 15.6 Write CD dialog box


Fig. 15.7 Burn process Status Windows


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located are called tracks. Up to 99 tracks may be stored on an Audio-CD. Onetrack generally corresponds to one piece of music on the CD.

SectorsThe track itself is made up of units called sectors. A sector contains 2352 bytes,of which - depending on the type of CD used - a different number may beused for user data. The sector generally consists of a header, synchronizationbits and user data. It may also have error recognition and correction data.To read a sector, a drive with single read speed requires 1/75th of a second.

Table of ContentsThe initial area of the CD is physically located at the inside of the CD surfaceand is approximately 4 mm wide. It contains the Table of Contents of the CD(TOC) and other information about the CD, such as the name, the author orthe date of the CD.

Single-Session, Multi-SessionThe term multi-session practically speaks for itself. A multi-session CD wasproduced in several sessions, that is, recording procedures. The individualsessions may have been written at random time intervals.

One session consists of at least one track.

A single-session CD is created in only one session, as the name implies. Audio-CDs are almost always single-session CDs, while CD-ROMs or Photo-CDsconsist of one or more sessions.

Disc At Once, Track At OnceToday, one differentiates between two different recording technologies with CDrecorders: Disc At Once and Track At Once. Newer recorders generally supportboth technologies, while older devices frequently can only handle Track AtOnce. For a recorder with Track At Once, every track is written separately.Therefore, pauses are unavoidably created between the tracks which cannotbe influenced by the recording software. In contrast to this, with Disc At Once,the entire CD is written in one procedure, which allows more freedom for therecording software, but at the same time prevents subsequent modifications.For many formats (Audio-CD) Disc At Once is more logical, since unnecessarypauses can be avoided, while Track At Once is generally used for multi-sessionCDs.

Choosing the Right CD-ROMCD-ROM drives aren't all the same. They vary in terms of their hardwareinterface, speed, drivers used, access to additional hardware, and where theyattach to the computer so that one can select the right one for needs,depending upon the following characteristics.


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Physical CharacteristicsPhysically, most CD-ROM drives look pretty much alike. The front paneltypically has a power-on indicator, CD busy signal, an Eject button, a manualeject hole, an audio jack, and a volume controller of some kind.DISC LoadingNot all computer-based CD players load discs the same way, as you may knowfrom using the audio devices. Although no longer manufactured, some CD-ROM drives used to require that you place the CD in caddy (a protectivestorage case that minimizes exposure to contaminants) for loading, and theninsert the caddy into the drive. Other drives have a tray that the disc goesdirectly into. Once you put the disc into the tray, it slides back into place inthe drive, and the CD starts spinning.

Although some caddy-style drives will play when the drive is on its side, so thatthe disc is positioned vertically rather than horizontally, some CD-ROM drivesmust be in a horizontal positions to run. Do not attempt to run a CD playerwhen it's on its side unless the drive is specifically listed as being able to supportthis position.

Internal or ExternalMany CD-ROM models are available in both internal and external flavors. Ifyou have an empty drive bay and don't mind opening up your system to installthe drive, internal drives are often the best choice. They tend to be lessexpensive than external drives, and more models are available. Additionally,some interfaces (such as IDE, for eg.,) aren't available at all in external models,so if you have an IDE controller that you want to use with the drive, internalis your only choice.

External drives are good for those with a USB or SCSI interface who don't likecracking the case, don't have an extra drive bay, or are running into a bit ofa power crunch from too many devices making demands on the power supply(external drives have their own power supply). They do tend to be moreexpensive than comparable internal drives, but (assuming that you have USBport or a SCSI host adapter installed in your computer), they're much easierand faster to install. Plugging an external USB drive into your computer is assimple as it gets.

Data Transfer RateData transfer rate, measured in kilobytes per second, is the measure of thequantity of data supplied to your computer at the onset of the first readoperation.

Access TimeAccess time is the amount of delay between the drive receiving the command


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to read and the actual beginning of the reading. It's measured in milliseconds(ms). The measurement is just an average; the actual speed depends on wherethe data is located on the disc and how quickly the read mechanism can getto it. The closer to the centre the data is, the quicker it can be accessed.

Caching

Disk caching temporarily stores recently accessed or frequently accessed data

to the hard disk, to take advantage of its higher access rates. Most CD-ROM

drives have a small amount of memory in them for this purpose. Typically, the

directory of the CD is cached. Caching the directory enables the computer to

more quickly navigate subdirectories and makes the CD-ROM drive appear

to be faster. However, the actual reading of the data is still slower.

BuffersA cache uses some form of logic to figure out what to store: depending onhow it's set up, it will temporarily store the most recently accessed or the mostfrequently accessed data on the hard disk.

Buffering is similar to caching, except that there's no logic as to how data goes

into it. Data is stored in the buffer until the CD-ROM drive is ready to send

the data to the CPU for processing. Buffer sizes can vary from 32KB to 2MB.

Although bigger is always better, you should look for a buffer of at least 512KB.

DVDDVD, which stands for Digital Versatile Disc, is the next generation of opticaldisc storage technology. It's essentially a bigger, faster CD that can hold videoas well as audio and computer data.

DVD aims to encompass home entertainment, computers, and business

information with a single digital format, eventually replacing audio CD,

videotape, laserdisc, CD-ROM, and perhaps even video game cartridges.

It's important to understand the difference between DVD-ROM and DVD-Video,

DVD Video (often simply called DVD, hence the earlier name Digital Video

Disk) holds video programs and is played in a DVD player hooked up to a

TV. DVD-ROM holds computer data and is ready by a DVD-ROM drive hooked

up to a computer.

The difference is similar to that between Audio CD and CD-ROM.

Commonly available DVD media, which offer 4.5 GB of disk space, costaround Rs. 160, while a DVD-writer would cost Rs. 7,000 and upwards.

The DVD, therefore, with times the storage space of a CD, offers itself as anaffordable alternative. Yes, it does take time to write a DVD, but it is far better


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than juggling around seven CDs.

Does this mean that it is good-bye to CD-burning? Definitely not.

How is DVD different from CD

For greater data density, there are smaller pits, a more closely spaced track

and a shorter wavelength red laser. The error correction is more robust, the

modulation scheme is more efficient. All this means that a standard DVD can

hold 4.7 gigabytes of data.

CD DVD

Disc Diameter 120 mm 120mm and 80mm

Disc Thickness 1.2mm 1.2mm

Disc Structure Single substrate Two bonded 0.6 mm substrates

Laser Wavelength 780mm (infrared) 650 and 635 nm (red)

Track Pitch 1.6um 0.74um

Shortest pit/and length 0.83um 0.4um

Data Layers 1 1 or 2

Data Capacity Aprox. 680 megabytes Single layer: 4.7GB ×2(side)

Dual layer: 8.5 GB × 2(side)

Reference Data Rate 153.6 kilobytes/sec 1,108 kilobytes/sec, nominal

to 176.4 kilobytes/sec

How DVD worksDVD is little more than souped-up CD-ROM technology. The disc packs seventimes the data onto the same surface area, but packaging tricks such as twosided disc further boost the capacity by up to 26 times that of a CD-ROM. DVDhas come bringing with it the ability to record and erase data on special read/write DCD-RAM discs.

Basic DVD physicsLike a CD-ROM, a DVD stores data in little pits in a single spiraling track ona reflective metal surface embedded in plastic. A laser in the drive reads thepits as zeros. The challenge in developing DVD was simple; increase datacapacity by packing as many pits as possible onto a disc using inexpensivetechnology.

The breakthrough was written in light; develop a shorter-frequency laser thatproduces a tighter beam, so smaller pits can be read. While the laser in anordinary CD-ROM drive has a 780-nanometer (nm.) wavelength, DVD drivesuse lasers with 650-nm or 635-nm wavelengths supporting more than doublethe pits per track, and more than double the tracks per recording surface.

Other advances, better error-correction code, and improved channel;modulation, raise the data density an additional one and a half times. Tighter


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manufacturing tolerances and a slightly bigger recording surface take DVDthe rest of the way to its basic 4.7 GB capacity.

The many sides of DVDMost DVD disc top out at 4.7GB. But two schemes for increasing density willsoon result in discs that can hold up to a whopping 17GB. Packing data ontwo sides is the simplest means of doubling capacity. Manufacturers realizedthat they could make a DVD as thin as 0.6 mm, or half the thickness of a CD,enabling them to bond two discs back-to-back and get 9.4GB of space. Thedrawback is that you have to flip the disc over.

The second technique, adding another data layer, doubles the capacity of asingle side. The first data layer is semi-transparent, so a second laser canpunch through it and read the layer beneath. This scheme sacrifice a littlecapacity, yielding 8.5GB per side. But you can bond two-dual-layer sidestogether to get that monster 17GB disk.

Speeds and feedsThe DVD drives actually spin DVDs slightly slower than an old-fashioned 3XCD-ROM drive spins CDs. But since data is packed much more tightly on aDVD, the throughput matches that of a 9X CD-ROM drive, about 1.3 megabytesper second (MB/sec). Newer drives have doubled this speed and can transferDVD data at up to 2.7MB/sec.

The higher throughput is glaringly obvious when you're watching movies. CD-ROM titles with video clips must assume they're dealing with a 2X or 4X drive,but DVD video is mastered for approximately 9X speed and makes CD-ROMvideo look jerky.

Increases in either DVD-ROM or CD-ROM speed beyond the mastered speedsdon't improve video quality; instead, you get faster software loading timesfrom DVD-ROM discs.

Performance hasn't improved much in one important area average accesstime, or how long it takes the laser to jump from track to track and retrieveDVD data. With average access times between, 150 and 200 milliseconds(ms). DVD-ROM drives won't run applications or find dispersed data withanything remotely resembling hard disk speeds, which are typically between9 ms and 12 ms. Seek time has no effect on DVD video, which is storedsequentially. But DVD ROM's, just like CD-ROMs, will be best used for loadingprograms and providing a huge reservoir of data (including video clips) forapplications that run off your hard disk.

DVD Media FormatsSome DVD media formats available: DVD-R ad DVD-RW Pioneer developedand released the DVD-R and DVD-RW formats in 1997. However, Pioneer was


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the only manufacturer at that time with such a product, and it did facecompatibility issues.

The DVD-R format is split into DVD-R (A) 'Authoring' and DVD-R (G) 'General'formats. They differ in terms of the laser use to write on them. The DVD-R (G)writes with a cheaper 650-nm (nanometre) laser, whereas DVD-R (A), intendedfor professional development, uses a 635-nm laser. The problem is that theseformats are not compatible with each other.

DVD-R(A) drives cannot record on DVD-R (G) disks, and vice-versa. Theircapacities also vary.

DVD-RAMIt's a fast-disappearing DVD format, unshered in just after the DVD-R madeits appearance. These disks are still preferred by those who munch video fora living. The reason was that it was the only format that allowed direct datamanipulation on the disk in real-time, without having to rewrite the whole disk.Initially, these disks came with a storage capacity of 2.8 GB, which laterincreased to 4.7 GB.

The DVD+R and DVD+RW formatsThe DVD+R and DVD+RW alliance was formed by Dell, Hewlett-PackardCompany, MCC/Verbatim, Philips Electronics, Ricoh Company Ltd, SonyCorporation, Thomson Multimedia and Yamaha Corporation. These companiesformed their own consortium and came up with these two formats.

They are relatively new. Worldwide, they were made available only in late2001. The DVD+R made its appearance only in mid-2002.

Advantages and DisadvantagesUnlike other formats, DVD-RAM media are disks housed in cartridges, whichDVD-ROM drives cannot read. A later version allowed the disk to be removedfrom the cartridge, but DVD-ROM drives still failed to read them.

DVD-Rs and DVD-RW's are incompatible with DVD+R and DVD+RW media.You cannot write to either of these disks using interchangeable writer drives.Hence, drive manufacturers came up with dual-format DVD drives that canactually write to all of them.

DVD-R media are written at a lower speed than that used for DVD+R media.Both have a theoretical limit of 16X, and a few DVD-writer drives write at 12X.The DVD-R format is yet to do so. The higher the media speed, the faster yourjob gets done, provided the drive writes at that speed. Another aspect is thefinalisation can add episodes of your favourite TV serial to a DVD+RW, andplay it instantly on a DVD player. However, DVD-RWs needs finalisation beforeplaying.


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Another factor is the mount Rainier support, the defacto standard with all futurereleases of Windows. It lets you write directly to a DVD+RW without any specialsoftware. Not so with the DVD-Rs and DVD-RWs since this was not specifiedin their format.

CompatibilityDVD-R, DVD-RW, DVD+R and DVD+RW media are compatible with 85 percent of the available standalone DVD players. As for DVD-RAM disks, they werenot designed for, and are not compatible with, any of the available DVDplayers. Only specialised drives, such as, the Iomega Super Drive read them.

The Dual-layer FormatAll available DVD media are limited to single-layered, single-sided mode(DVD-5) and hold up to 4.7 GB of data. Some manufacturers sell dual-sided,single-layered media (DVD-10), but these are a fast disappearing specie sincethe same amount of data fits onto single-sided, dual-layered DVD-9 disks. Thisalso provides less clutter since you are effectively stuffing two disks worth ofdata on a single disk.

Philips and Mitsubishi Kagaku Media developed the first DVD-R and DVD+RWdual-layered media, meant for general users. Not to be left behind, Pioneerreleased a dual-layer format of the DVD-R.

As of now, only dual-layered DVD+Rs and DVD+RWs are available.

Two media layers are separated from each other on one single side of the disk.While writing, the first layer is written with the same speed as that used on asingle-layered disk. As the laser switches to the second layer, the speeddecreases and the data is written at a much slower speed.

For eg., the DVD-Writer may slow down from 4X to 2.4X. The point at whichthis switch occurs is a known issue for the current crops of DVD-ROM drivesavailable in the market.

DVD VideoDVD is vastly superior to video tape and generally better than laser-disc.However, quality depends on many production factors. Until compressionexperience and technology improves we will occasionally see DVD's that areinferior to laser-disc. Also, since large amounts of video have already beenencoded for Video CD using MPEG-1, a few low-budget DVD's will use thatformat (which is not better than VHS) instead of higher-quality MPEG-2.

The CCIR-601 digital video standard specifies a video rate of 167 megabitsper second. At this bit rate, the 4.7 gigabyte capacity of standard DVD couldonly store roughly 4 minutes of digital video! Thus some form of datacompression is required.


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DVD has taken advantage of sophisticated compression technology calledMPEG2. It's a set of flexible compression standards, the second to emergefrom the Moving Picture Experts Group (MPEG).

MPEG2 works by analysing the video picture for repetition called redundancy.In fact, over 97% of the digital data that represent a video signal is redundant,and can be compressed without visibly harming the picture quality. Byeliminating redundancy, MPEG2 achieves superb pictures at far lower bitrates.

As implemented for DVD, MPEG2 encoding is a two-stage process, where thesignal is first evaluated for complexity. Then, higher bit rates are assigned tocomplex picture and lower bit rates to complex picture, using an "adaptive",variable bit-rate process.

The DVD format compresses video to bit rates with a range of upto 10megabits persecond. Although the "average" bit rate for digital video is oftenquoted as 3.5 megabits per second, the actual figure will vary according tomovie length, picture complexity and the number of audio channels required.

Thanks to MPEG2 compression a single layer, single-sided DVD has enoughcapacity to hold two hours and 13 minutes of spectacular video on a 4-3/4inch disc! At the nominal average data rate of 3.5 megabits per second, thisstill leaves enough capacity for discrete 5.1 channel digital sound, plussubtitles! Including video, audio and subtitles, the total average data rate is4.962 megabits per second. And because it's single-sided, DVD can store allthis with no need to flip the disc over.

Movie DVD's released will be capable of carrying Dobly Digital (AC-3) audiosound tracks with other 2 or 5.1 channels. Unlike Dobly Pro Logic coding.Dolby Digital (AC-3) multi-channel sound provides five completely separatedistinct) channels: Left, Centre, Right, Left-Rear and Right-Rear, plus a commonsubwoofer channel.

Dolby-Digital (AC-3), which uses a digital bit rate of 384 kilobits per second,is already well accepted.

As an option to Dolby Digital (AC-3) sound, DVD also enables producers tochoose CD quality stereo sound with Dolby Pro Logic encoding.

The Interactive featuresDVD-Video players (and software DVD-Video Navigators) support a commandset that provides interactivity.

The main feature is menus, which are present on almost all discs to allowcontent selection and feature control. Each menu has a still-frame graphic andupto 36 highlightable, rectangular "buttons". Remote control units have four


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arrow keys for selecting on screen buttons, plus numeric keys, select key, menukey, and return key.

Additional remote functions may include freeze, step, slow, fast, scan, next,previous, audio select, subtitle select, camera angle select, play mode select,search to program, search to part of title (chapter), search to time, and searchto camera angle. The producer of the disc can disable any of these features.

Additional material for camera angles and seamless branching is interleavedtogether in small chunks. The player jumps from chunk to chunk, skipping overunused angles or branches, to stitch together the seamless video. Since anglesare stored separately, they have no direct effect on the bit-rate but they doaffect the playing time. Adding 1 camera angle for a program roughly doublesthe amount of space it requires there by cutting the playtime in half.

What are the sizes and capacities of DVDThere are many variations on the DVD theme.There are two physical sizes: 12 cm (4.7 inches) and 8 cm (3.1 inches), both1.2 mm thick.A DVD disc can be single-sided or double-sided.Each side can have one or two layers of data.The amount video a disc can hold depends on how much audio accompaniesit and how heavily the video and audio are compressed.At a rough average rate of 4.7 Mbps (3.5 Mbps for video, 1.2 Mbps for three5.1 channel soundtracks), single-layer DVD holds around 135 minutes.A two-hour movie with three soundtracks can average 5.2 Mpbs.A dual-layer disc can hold a two-hour movie at an average of 9.5 Mbps.

Notation and unitsThere's confusion of units of measurement in the DVD world.For eg. a single-layer DVD holds 4.7 billion bytes (G bytes), not 4.7 gigabytes(GB). It only holds 4.38 gigabytes.

Likewise, a double-sided, dual-layer DVD holds only 15.90 gigabytes, whichis 17 billion bytes.

Troubleshooting Optical Drives:

(i) Failure Reading a CD

If your CD fails to read a CD, try the following solutions:

_ Check for scratches on the CD data surface.

_ Check the drive for dust and dirt; use a cleaning CD.

_ Make sure the drive shows up as a working device in System Properties.

_ Try a CD that you know to work.


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_ Restart the computer (the magic cure-all).

_ Remove the drive from Device Manager in Windows 9x, allow thesystem to redetect the drive, and then reinstall the drivers (if PnP-basedsystem).

(ii) Failure to Read CD-R, CD-RW Discs in CD-ROM or DVD Drive.

If your CD-ROM or DVD drive fails to read CD-R and CD-RW discs, try thefollowing solutions:

_ Check compatibility; some very old 1x CD-ROM drives can't read CD-R media. Replace the drive with a newer, faster, cheaper model.

_ Many early-model DVD drives can't read CD-R, CD-RW media; checkcompatibility.

_ The CD-ROM drive must be MultiRead compatible to read CD-RWbecause of the lower reflectivity of the media; replace the drive.

_ If some CD-Rs but not others can be read, check the media colorcombination to see whether some color combinations work better thanothers; change the brand of media.

_ Packet-written CD-Rs (from Adaptec DirectCD and backup programs)can't be read on MSDOS/ Windows 3.1 CD-ROM drives because of thelimitations of the operating system.

iii) Trouble Making Bootable CDs

If you are having problems creating a bootable CD, try these possiblesolutions:

_ Check the contents of bootable floppy disk from which you copied theboot image. To access the entire contents of a CD, a bootable disk mustcontain CD-ROM drivers, AUTOEXEC.BAT, and CONFIG.SYS.

_ Use the ISO 9660 format. Don't use the Joliet format because it is forlong-filename CDs and can't boot.

_ Check your system's BIOS for boot compliance and boot order; the CD-ROM should be listed first.

_ SCSI CD-ROMs need a SCSI card with BIOS and bootable capabilityas well as special motherboard BIOS settings.

How Blu-ray Discs WorkIntroduction to How Blu-ray Discs WorkIn 1997, a new technology emerged that brought digital sound and video intohomes all over the world. It was called DVD, and it revolutionized the movieindustry.The industry is set for yet another revolution with the introduction of Blu-ray


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Discs (BD) in 2006. With their high storage capacity, Blu-ray discs can holdand play back large quantities of high-definition video and audio, as well asphotos, data and other digital content.In this article, HowStuffWorks explains how the Blu-ray disc works and how itwas developed, and we'll see how it stacks up against some other new digitalvideo formats on the horizon.A current, single-sided, standard DVD can hold 4.7 GB (gigabytes) of information.That's about the size of an average two-hour, standard-definition movie witha few extra features. But a high-definition movie, which has a much clearerimage (see How Digital Television Works), takes up about five times morebandwidth and therefore requires a disc with about five times more storage.As TV sets and movie studios make the move to high definition, consumersare going to need playback systems with a lot more storage capacity.Blu-ray is the next-generation digital video disc. It can record, store and playback high-definition video and digital audio, as well as computer data. The©CMS INSTITUTE 2012


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advantage to Blu-ray is the sheer amount of information it can hold:

• A single-layer Blu-ray disc, which is roughly the same size as a DVD, canhold up to 27 GB of data -- that's more than two hours of high-definitionvideo or about 13 hours of standard video.

• A double-layer Blu-ray disc can store up to 50 GB, enough to hold about4.5 hours of high-definition video or more than 20 hours of standard video.And there are even plans in the works to develop a disc with twice thatamount of storage.

Blu-ray discs not only have more storage capacity than traditional DVDs, butthey also offer a new level of interactivity. Users will be able to connect to theInternet and instantly download subtitles and other interactive movie features.With Blu-ray, you can:

• record high-definition television (HDTV) without any quality lossinstantly skip to any spot on the disc

• record one program while watching another on the disc

• create playlists

• edit or reorder programs recorded on the disc

• automatically search for an empty space on the disc to avoid recordingover a program

• access the Web to download subtitles and other extra featuresDiscs store digitally encoded video and audio information in pits -- spiralgrooves that run from the center of the disc to its edges. A laser reads the otherside of these pits -- the bumps -- to play the movie or program that is storedon the DVD. The more data that is contained on a disc, the smaller and moreclosely packed the pits must be. The smaller the pits (and therefore the bumps),the more precise the reading laser must be.Unlike current DVDs, which use a red laser to read and write data, Blu-ray usesa blue laser (which is where the format gets its name). A blue laser has a shorterwavelength (405 nanometers) than a red laser (650 nanometers). The smallerbeam focuses more precisely, enabling it to read information recorded in pitsthat are only 0.15 microns (µm) (1 micron = 10-6 meters) long -- this is morethan twice as small as the pits on a DVD. Plus, Blu-ray has reduced the trackpitch from 0.74 microns to 0.32 microns. The smaller pits, smaller beam andshorter track pitch together enable a single-layer Blu-ray disc to hold more than25 GB of information -- about five times the amount of information that canbe stored on a DVD.Each Blu-ray disc is about the same thickness (1.2 millimeters) as a DVD. Butthe two types of discs store data differently. In a DVD, the data is sandwiched


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between two polycarbonate layers, each 0.6-mm thick. Having a polycarbonatelayer on top of the data can cause a problem called birefringence, in whichthe substrate layer refracts the laser light into two separate beams. If the beamis split too widely, the disc cannot be read. Also, if the DVD surface is not exactlyflat, and is therefore not exactly perpendicular to the beam, it can lead to aproblem known as disc tilt, in which the laser beam is distorted. All of theseissues lead to a very involved manufacturing process.

How Blu-ray Reads DataThe Blu-ray disc overcomes DVD-reading issues by placing the data on topof a 1.1-mm-thick polycarbonate layer. Having the data on top preventsbirefringence and therefore prevents readability problems. And, with therecording layer sitting closer to the objective lens of the reading mechanism,the problem of disc tilt is virtually eliminated. Because the data is closer tothe surface, a hard coating is placed on the outside of the disc to protect itfrom scratches and fingerprints.The design of the Blu-ray discs saves on manufacturing costs. Traditional DVDsare built by injection molding the two 0.6-mm discs between which therecording layer is sandwiched. The process must be done very carefully toprevent birefringence.



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1. The two discs are molded.2. The recording layer is added to one of the discs.3. The two discs are glued together.Blu-ray discs only do the injection-molding process on a single 1.1-mm disc,which reduces cost. That savings balances out the cost of adding the protectivelayer, so the end price is no more than the price of a regular DVD.

Blu-ray also has a higher data transfer rate -- 36 Mbps (megabits per second)-- than today's DVDs, which transfer at 10 Mbps. A Blu-ray disc can record 25GB of material in just over an hour and a half.



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LAB EXERCISE 15.1 : Identification of Optical Storage Device parts

Objective: To be familiar with the different parts of the Optical Storage deviceas well as burning a CD using Nero.

Tasks:

1. Open a scrap CDROM drive and identify the different components such asthe different drive motors, the lens, interface type, etc.

2. After connecting the CDROM drive and configuring it appropriately usingjumpers, install the software Nero 5.0 or versions above it.

3. Try burning a CD-R using with as well as without the wizard.

4. Now try burning the CD-R using multi-session i.e. writing data on the CDonly half the capacity initially then writing the remaining half after some time.

SMPSCMS COMPUTER INSTITUTE

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Evolution of the Switch Mode Power SupplyThe power supply section that does the job of converting the available sourceof power into different voltages as required by the system, is one of the mostimportant sections of the system. Power supplies like other modules have alsopassed through various stages of evolution with the invention and subsequentdevelopment of different component technologies from the age old vacuumtubes to the present day integrated circuits. It has brought down the size ofthe power supply from large rack mounted units to compact hand-heldmodules for more or less identical Output power capability. In addition, thecontemporary power supplies are capable of having far better performancespecifications in terms of regulation efficiency, reliability etc.

One way to classify power supplies is to name them as AC/DC power supplies,DC/DC power supplies and DC/AC power supplies. An AC/DC power supplyconverts AC mains (230V, 50Hz) into required DC voltages. DC/DC powersupplies are used in portable system. DC/AC power supplies are used inportable mains operatable systems and in supplement to AC mains innonportable mains operatable systems where a disruption in power supply canaffect the job being done by the system. An inverter is part of UPS and is verypopular with the people using computer systems.

Based on the regulation concept, the power supplies are classified as eitherlinear or switched mode.

Linear Power SupplyConventional AC/DC power supplies comprising a transformer, rectifier, filterand regulator (series on shunt) constitute the linear power supplies. In linearpower supply, the active device that provides regulation, is always operatedin active or linear region of its characteristics. Any change in Output due tochange in input voltage or load current results in change in voltage drop acrossthe regulator transistor (in case of series regulator) or a change in currentthrough the regulator transistor (in case of shunt regulator) so as to maintaina constant Output voltage across the load.

SMPS

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INSTITUTE

16PC ENGINEERING


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Switched Mode Power SupplyDC to DC converters and DC to AC inverters belongto the category of switched mode power supplies(SMPS). Besides, there are SMPS, operating from mains,called off-line switching supplies. An off-line switchingsupply can be distinguished from a conventional AC--DC supply, as in case of former AC mains rectified andfiltered without using an Input transformer, and DCvoltage so obtained is then used as an Input to aswitching type DC to DC converter.

In switching power supply, the active device thatprovides regulation is always operated in switchedmode, i.e. it is operated either in cut-off or in saturation.

The Input DC is chopped at a high freq. (10khz to 100khz) using a active deviceand converter transformer. The transformed, chopped waveform is rectifiedand filtered. A sample of Output voltage is used as feedback signal for thedrive circuit for switching transistor to achieve regulation.

Power electronics is entirely devoted to switch mode power conversion anddeals with modem problems in analysis, design and synthesis of electroniccircuits as applied to efficient conversion, control and regulation and electricalenergy. Design and optimization of DC to DC converters which offer the highestpower efficiency, small size and weight and high performance, are alsoincluded in power electronics.

These DC to DC converters with isolation transformers can have multipleoutputs of various magnitudes and polarities. The regulated power supply ofthis type has wide applications, particularly in computer systems, wherein lowvoltage high current power supply with low Output ripple and fast transientresponse are mandatory. In addition these converters, connected in particularconfiguration result in switched mode AC power amplifiers with enoughbandwidth and high efficiency off line switches, DC to DC single and multipleOutput power supplies (battery charger and discharger), DC to DC inverters,DC to DC uninterruptible power supplies, DC to DC motor control, power servocontrol, robotics and switching audio amplifiers etc. are some of the examplesof switch mode power supplies.

Switch mode power supplies have come into wide spread use in the lastdecade. An essential feature of efficient electronic power processing is the useof semi-conductors in a power switching mode (to achieve minimum losses)to control the transfer of energy from source to load through the use of pulsewidth modulated or resonant techniques. Inductive and capacitive energystorage, elements, are used to smooth the flow of energy while keeping to a


Fig. 16.1 SMPS unit


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low level. As frequency of switching increases the size of magnetic andcapacitive element decreases in a direct proportion. Because of their superiorperformance i.e.. high efficiency, small size and weight and relatively low cost,they are displacing conventional linear power, supplies even at very low powerlevels.

Industry has been quick to realize that the energy saving technique also affordsthe opportunity to make dramatic reductions in equipment size and weight.

Changeover from Linear to Switching SuppliesLinear supplies are well-known for their extremely good line and load regulation,low Output voltage ripple and almost negligible RFI/EMI. Switching powersupplies on the other hand have much higher efficiency (typically 80 percentagainst 50 percent in case of linear supplies) and reduced size/weight for givenpower delivering capability. Quite often, compactness and efficiency are twomajor selection criteria. An improved efficiency and reduced size/weight areparticularly significant when designing a power supply for portable systemwhere a number of different regulated Output voltages are required. Also,unlike linear supplies, efficiency in switching supplies does not suffer as theunregulated Input regulated Output differential becomes large.

In systems operating from battery packs and requiring higher DC voltages for

their operation, the switching supply is the only option. We cannot use a linear

regulator, for instance, to change an unregulated Input of 24 V DC into

regulated Output 1000 V DC.

Table-1 compares the major characteristics of linear and switching supplies.

The characteristics which are significant from a designer's point of view and

where a switching supply has high degree of superiority over a linear supply

are efficiency and power density. While power density indicates the size and

weight vis-a-vis power delivering capability, the transient recovery time is time

required by supply Output voltages to settle within the accuracy limits after a

step change in load current or the unregulated Input.

Although use of switching supplies in the early days of their development was

continued to military and aerospace systems, in recent years; they have found

application in practical industrial and consumer applications due to easy

availability of switching components like transistors, fast recovery rectifiers etc.

with enhanced features and an affordable price.TABLE - 1

Parameters Linear Switching

Line Regulation 0.05 - 0.05 % 0.05 - 0.1 %

Load Regulation 0.02 -0.10 % 0.10 1.0 %


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Output ripple 1.5 - 5 MV 25 - 100 MVEfficiency 40 - 50 % 70 - 90 %

3 3Power Density 0.5 W/inch 2.5 W/inch

Transient Recovery 50 Us 200 UsHold up time 2 MS 32 MS

Switch Mode Power Supply for Personal ComputerOperating System CharacteristicsThe PSU supplies various voltages and power signals necessary for theoperation of PC's system board, keyboard and other installable optional cards.The PSU is a conventional desktop system designed to convert either 115W60Hz A.C. or 230V 50Hz. It can be operated over an input voltage range of190 V to 240 V AC and provides four regulated DC output voltages of 3.3V,+5V, -5V, +12V and -12V.

Table 1 shows the current rating and regulation requirements of each of thesesupply voltages. These outputs are over voltage, over current and open circuitprotected. The input portion of PSU is protected by a fuse of suitable rating.

The 3.3V powers the chipsets, DIMMs, PCI/AGP cards and miscellaneous chips.

The +5V DC powers the logic on the system board, the disc drives SIMMs andexpansion cards in the system expansion slots. The +12V is used for the discdrive motors. It is assumed that only one drive is active at a time. The -5V DClevel is designed for dynamic memory bias voltage and has a longer decayon power off than +5V and -12V outputs.

Power Good SignalThe power supply ensures that the system does not run unless the powersupplied is sufficient to operate the system properly. In other words, the powersupply actually prevents the computer from starting up or operating until allthe power supply voltages are within the proper ranges.

The power supply completes internal checks and tests before allowing thesystem to start. If the tests are successful, the power supply sends a specialsignal to the motherboard, called Power Good. This signal must be continuouslypresent for the system to run. Therefore, when the AC voltage dips and thepower supply cannot maintain outputs within regulation tolerance, the PowerGood signal is withdrawn (goes low) and forces the system to reset. The systemwill not restart until the Power Good signal returns.

The Power Good signal (sometimes called Power OK or PWR_OK) is a +5V(nominal) active high signal (with variation from +2.4V through +6.0V generallybeing considered acceptable) that is supplied to the motherboard when the

Parameters Linear Switching


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power supply has passed its internal self tests and the output voltages havestabilized. This normally takes place anywhere from 100ms to 500ms (0.1-0.5 seconds) after you turn on the power supply switch. The power supply thensends the Power Good signal to the motherboard, where the processor timerchip that controls the reset line to the processor receives it.

In the absence of Power Good, the timer chip holds the reset line on theprocessor, which prevents the system from running under bad or unstable powerconditions. When the timer chip receives the Power Good signal, it releasesthe reset, and the processor begins executing whatever code is at address FFFF.

On pre-ATX systems, the Power Good connection is made via connector P8-1 (P8 Pin 1) from the power supply to the motherboard. ATX and later systemsuse pin 8 of the 20-pin connector, which is normally a gray wire.

Basic Block Diagram of SMPSFig. 16.2 shows the block diagram of the PSU. The input from mains is firstfiltered to suppress any spikes/surges entering the power supply circuit. Thisis an important part of the circuit and helps in preventing data loss or erroneousworking during power line disturbances.

Filtered mains supply is then rectified by a full-wave bridge rectifier to produce+150V DC for the power converter section. The input supply is switched withthe help of this power converter and the energy transferred to the outputthrough a high frequency ferrite transformer.

The power converter consists of two externally driven transistors operating inpush-pull configuration. These are driven by converter driver. The power

converter transformerproduces low voltageswitched waveforms onthe secondary side whichare rectified and filteredto produce wellregulated ±5V and±12V DC outputvoltages.

The ±5V DC outputvoltage is sensed bycontrol section of thePSU which essentiallyconsists of a pulse widthmodulator (PWM)

controller IC. This PWM produces suitable drive pulses at about 22kHz for the

AC FuseLineFilter

Full W aveBridge

Recti fierPush PullConverter

OutputRecti fierand Fil ter

AC Input Section Power Section Output Section

+ 5V+12V- 5V-12V

PowerGoodSignal

ConverterDr iver

PulseWidth

Modulator

OverCurrentSense

VoltageSense

Control Section


Fig. 16.2 Blockdiagram of SMPS


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Fig. 16.3 PC/XT/AT FormFactor Power Supply

converter driver. The width of these pulses is controlled by the modulatordepending upon the output sense voltages, thus ensuring correct operatingvoltages at the output and providing necessary protection to the PSU.

The input mains supply is applied to the circuit via an on-off switch of fuse F1.Power converters operating directly ‘off-line’ like this one draw heavy currentwhen switched on. This inrush of current causes great stress on input components,switches, rectifiers and capacitors.

For low power applications, simple series resistor is used to limit the initial highvoltage and high current. Special high current surge rated resistors are bestsuited for this application. However, adequately rated wirewound resistor alsoserves the purpose and is frequently used.

Power Supply Form FactorAlthough the names of the power supply form factors will seem to be the sameas those of motherboard form factors, the power supply form factor is morerelated to the system chassis (case) than the motherboard. That is because allthe form factors use one of only two types of connector designs, either AT orATX.

All power supplies are categorized by several characteristics, one of which isthe form factor. This term describes the physical dimensions of the power supplyand the types of power connectors it provides to power the motherboard. Theform factors encountered are as follows.

PC/XT/AT Form FactorsThe original power supply form factorgot its name from the IBM PC/XT. Inaddition to the power connectors ofthe peripherals, the power supplyalso provided a motherboard powerconnection using two separateconnectors, called P8 and P9, thatplugged side-by-side into themotherboard. In 1984 IBMintroduced the successor to the PC/XT: the AT. While the power supply'sphysical dimensions changed, theAT had the same motherboard anddrive connections as the PC/XT formfactor. The AT also featured a remote

power switch, which appeared on the first tower-style case, allowed users topower up their computers from the front rather than having to reach around

+12 V (Yellow)GND (Black)GND (Black)+5 V (Red)

GND (Black)GND (Black)-5 V (White)+5 V (Red)+5 V (Red)+5 V (Red)

PWR_OK (Orange)+5 V (Red)+12 V (Yellow)-12 V (Blue)GND (Black)GND (Black)





Pin 1Pin 2Pin 3Pin 4




48mm

120mm

10 10

142mm

100mm

12mm

100mm

8mm

120mm

210mm

222mm

1220mm


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to the back or side. The AT form factor isno longer in use, except in very oldcomputers running 286 CPUs. It wasreplaced by the Baby AT form factor.

Baby AT/LPX Form FactorThe Baby AT form factor got its name fromthe simple fact that it was a smaller versionof the original AT form factor. With theexception of its smaller physical size, theBaby AT had the same power connectorsas the AT and was used as a replacementfor AT form factor power supplies. Aroundthe same time, another version of the BabyAT appeared under several differentnames, including slimline (because it was

found in cases bearing the same name), PS/2 (after the short-lived series ofcomputers), and LPX (for low profile). While the LPX is physically smaller thanthe Baby AT, its output connectors are the same as the AT, with one smallexception: the monitor pass-through power connector at the rear of the powersupply began to disappear with the LPX form factor. As popular as these twoform factors were, they were eventually replaced by the ATX.

ATX/NLX Form FactorThe year 1995 saw the introduction of the ATX form factor, and it was the first

time that a genuine standard forboth motherboards and theirassociated power supplies wascreated. Physically, the ATX powersupply was almost identical to theBaby AT/LPX form factor, howeversignificant changes occurred in boththe output voltages and theconnectors. A single 20-pinconnector replaced the two separateconnectors, P8 and P9. The ATX wasthe first power supply to provide3.3 volts, and it introduced the first"soft power" switch, which allowedsoftware to turn the computer on

and off. The ATX power supply was designed for the NLX form factor


+5 V (Red)GND (Black)GND (Black)+12 V (Yellow)





PWR_OK (Orange)+5 V (Red)+12 V (Yellow)-12 V (Blue)GND (Black)GND (Black)

GND (Black)GND (Black)-5 V (White)+5 V (Red)+5 V (Red)+5 V (Red)

Fig. 16.5 Baby AT FormFactor Power Supply


+5 V (Red)GND (Black)GND (Black)+12 V (Yellow)




+12 V (Yellow)GND (Black)GND (Black)+5 V (Red) Pin 1 Pin 11

Orange +3.3V

Orange +3.3V

Black GND

Red +5V

Black GND

Red +5V

Black GND

Grey PWR_OK

Purple +5VSB

Yellow +12V

+3.3V Orange

-12V Blue

GND Black

PS ON Green

GND Black

GND Black

GND Black

-5V White

+5V Red

+5V Red

Pin 10 Pin 20 ATX Power ConnectorPin Out

Fig. 16.4 Baby AT FormFactor Power Supply






150mm

150mm

150mm

150mm 131mm

510

5 10

150mm

86mm

5 7

64mm

6

86mm

16mm

6mm

120mm

140mm

186mm







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motherboard, which is one of the reasons that the ATX power supply form factoris sometimes (and incorrectly) called the NLX power supply.

Mini-ATX/Micro-ATX/SFX Form FactorMini-ATX, Micro-ATX, and SFX all describe a single form factor that is physicallysmaller than the ATX and does not have a -5 volt signal, which is only neededby some older expansion bus (ISA) cards.

ATX12V Form FactorThe newest form factor, a superset ATX called the ATX12V, was created forsystems using P4 and high-end Athlon processors. The ATX 12V adds an extra

+12V power connector that enables the deliveryof more current to the high-end processor-basedboards. If you see a +12V 4-pin connector, youhave an ATX12V power supply. If you don't find a+12V 4-pin connector, your power supply is anATX version.

Form Factor WTXAny discussion of power supply form factors mustinclude the WTX, which was introduced by Intel in1998. This form factor is usually only seen onlarger, more powerful systems (the W in WTXstands for workstation). The WTX is completelydifferent from all earlier form factors. It is designedfor multiple-CPU and multiple-drive systems, such

as servers and high-end engineering workstations.

Connectors from SMPSMolex ConnectorsThe first and most common type of connection iscalled the Molex. The Molex connector is primarilyused for devices that need both 12V and 5V ofpower. The Molex connector has chamfers (notches),which make for easy installation. These chamferscan be defeated if one pushes hard enough, soalways inspect the Molex connection to ensureproper orientation before one installs it.

Mini ConnectorsMost systems also provide a mini connector. Themini is used primarily on 3.5-inch floppy drives,

because floppy drive makers have adopted the mini connector for that use.

Fig. 16.6 Standard MolexConnector

Fig. 16.7 Standard MiniConnector




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Be careful about installing the mini connectors!Whereas Molex connectors are extremelydifficult (but not impossible) to install incorrectlyinto a Molex socket, inserting a mini incorrectlytakes very little effort. Installing a miniincorrectly may destroy the device.

Motherboard ConnectorsAT ConnectorsIndustry standard PC, XT, AT, Baby-AT, and LPX

motherboards all use the same type of main power supply connectors. Thesesupplies feature two main power connectors (P8 and P9), each with 6 pins that

attach the power supply to the motherboard.

P8 and P9 are identically sized and shaped; theonly difference is the colors of wires and the orderin which they appear. You have to get them pluggedin right or you will irreparably smoke yourmotherboard. Just keep this in mind: blacktogether. Both connectors have a black wire; whenthe connectors are plugged in properly, the blackwire on P8 will be next to the black wire on P9.

ATX ConnectorsThe industry standard ATX power-supply-to-motherboard main connector is the Molex 39-29-

9202 (or equivalent) 20-pin ATX style connector. It is used in the ATX, Mini-ATX,Micro-ATX & SFX form factors. This is a 20-pin keyed connector with pinsconfigured as shown in Table 16.4. The colors for the wires listed are those

recommended by the ATX standard; however, theyare not required for compliance to the specification,so they could vary from manufacturer tomanufacturer.

ATX12V ConnectorTo augment the supply of +12V power to themotherboard, Intel created a new ATX12V powersupply specification. This adds a third powerconnector, called the ATX12V connector, specificallyto supply additional +12V power to the board.

Power SwitchEvery PC needs a power switch. Power switch


Fig. 16.8 A Standard P8and P9 socket



Fig. 16.9 P8 and P9connectors

Fig. 16.10 ATX P1 connector


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utilization creates one of the major differencesbetween AT and ATX power supplies. AT powerswitches simply turn the system on or off,whereas ATX power supplies use a featurecalled soft power.

AT Power SwitchAT power switches come in only two commontypes: rocker and plunger. Each of these

switches has four tab connectors that attach to four color-coded wires leadingfrom the power supply.

The ends of the cable are fitted with spade connector lugs, which plug ontothe spade connectors on the power switch. The cable from the power supplyto the switch in the case contains four color-coded wires. In addition, a fifthwire supplying a ground connection to the case might be included. The switchwas usually included with the power supply and heavily shrink-wrapped orinsulated where the connector lugs attached to prevent electric shock. The fouror five wires are color-coded as follows:

• Brown and blue: These wires are the live and neutral feed wires from the110V power cord to the power supply. These are always hot when the powersupply is plugged in.

• Black and white: These wires carry the AC feed from theswitch back to the power supply. These leads should behot only when the power supply is plugged in and theswitch is turned on.

• Green or green with a yellow stripe: This is the groundlead. It should be connected to the PC case and shouldhelp ground the power supply to the case.

On the switch, the tabs for the leads are usually color-coded;if not, you'll find that most switches have two parallel tabs and two angled tabs.If no color-coding is on the switch, plug the blue and brown wires onto the tabs

that are parallel to each other and the blackand white wires to the tabs that are angledaway from each other. If none of the tabsare angled, simply make sure the blue andbrown wires are plugged into the mostclosely spaced tabs on one side of theswitch and the black and white wires on the

most closely spaced tabs on the other side.

As long as the blue and brown wires are on, one set of tabs and the black



Fig. 16.12 Types ofSwitches

Plunger type Rocker type


Fig. 16.13 Correct wireplacement for AT powersupply

Fig. 16.11 ATX P1 socket


237

and white leads are on the other, the switch and supply will work properly. Ifyou incorrectly mix the leads, you will likely blow the circuit breaker for thewall socket because mixing them can create a direct short circuit.

Power Supply Ratings

A system manufacturer should be able to provide you the technical specificationsof the power supplies it uses in its systems. Table 16.15 shows the rated outputsat each of the voltage levels for supplies with different manufacturer-specifiedoutput ratings.PC Power and Cooling ATX Power Supply Output Ratings

Rated Output 235W 275W 300W 350W 400W 425W

Output current (amps)+5V 220 30.0 30.0 32.0 30.0 50.0

+3.3V 14.0 14.0 14.0 28.0 28.0 40.0Max watts +5 and +3.3V 125W 150W 150W 215W 215W 300W

+12V 8.0 10.0 12.0 10.0 14.0 15.0-5V 0.5 0.5 0.5 0.3 1.0 0.3

-12V 1.0 1.0 1.0 0.8 1.0 1.0

Most PC power supplies have ratings between 150 and 300 watts. Althoughlesser ratings are not usually desirable, you can purchase heavy-duty powersupplies for most systems that have outputs as high as 600 watts or more. The300-watt and larger units are recommended for fully optioned desktops. Thesesupplies run any combination of motherboard and expansion card, as well asa large number of disk drives and other peripherals.

Troubleshooting tips for SMPS

• Check the wall outlet. The outlet should be providing between 220-250VAC current. Just set the voltage-ohmmeter (VOM) to read AC voltage andput one lead in each hole of the outlet.

• Check the power cord. It should be firmly plugged into the power supply.If you have a spare cord, swap cords. Yes, power cords do fail.

• Is power getting to the power supply? The fan gets it first, so if it isn't turningon, the power supply isn't getting power. When some power supplies arefirst turned on, the speaker emits a low click.

• Check to make sure the power supply is connected to the motherboardusing the right connectors, whether P8 and P9 (AT) or the single-piece, 20-pin ATX connector.

• To conclude whether the problem is with the motherboard or SMPS, short


238

the PS ON pin (Green pin) with any black pin i.e. the ground, and observewhether the SMPS fan has started. If it has, then it can be concluded thatthe source of the problem is with the motherboard, else it will be with theSMPS.

• If all those things check out correctly, try swapping in a different powersupply.

LAB EXERCISE 16.1 : SMPS Connector Identification

Objective: To be familiar with the different types of power supplies and their con-nectors and be able to do preliminary analysis on the supplies.

Tasks:1. With the help of a multi-meter, measure the line voltage from the line or wall

outlet, which will act as the input to the SMPS.2. In the case of an AT power supply, identify the different connectors and then

make the connections to the power switch i.e. as mentioned in the chapter.3. In the case of an ATX power supply, identify the different connectors from the

supply unit.

UPSCMS COMPUTER INSTITUTE

239

UPS

Concept of UPSUPS is an abbreviation of Uninterrupted Power Supply. It iscombination of both electrical and electronics systems designedto provide a total continuity of AC power to a critical computerizedload (eliminating all kind of disturbances) even in the absenceof mains power.

A UPS draws AC power from the commercial AC line and processesit to a required condition, at the same time charging the batterywhich is connected to the UPS. Even if the AC mains fail, itprovides an output voltage (without any interruptions) from thebattery sources.

Necessity of UPSMost of the highly sophisticated equipment like computers, medical equipmentand satellite communication systems have to be run continuously without anykind of interruption. Even a short interruption may cause a serious disaster.Furthermore, with the advances in the computer technology and its vastapplication almost every corner of the world and also its expansion incomputer networking like LAN, WAN etc., power plays a very important rolein keeping the system in working condition. The voltage that should be givento a computer system should be a pure sine wave (as shown in figure 17.2)

and it should be free from all kinds ofdistortion.

The AC voltage that is received fromthe commercial line may consist ofdifferent kinds of distortion like spikes,surges, sags, brown-outs, black-outsetc., as shown in the fig. 17.3.

SpikesSpikes are very high voltages which are caused due to the switching ON or

CMS COMPUTER

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17PC ENGINEERING


Si newavef T

0 t

Fig. 17.2 Pure Sine Wave


Fig. 17.1 UPS Unit


240

switching OFF of a large electricalload.SurgesSurges are over voltages that last formore than one cycle. They are causeddue to some heavy electrical load whichis suddenly switched OFF.

SagsSags are under voltages that last formore than one cycle.

Brown-OutsBrown-outs are the low voltageconditions that can be present even forseveral hours. This is often createdwhen the power demands exceed tocapacity of the power supply.

Black-OutsBlack-outs are nothing but no-powerconditions, caused due to severalfactors like, short circuits, fuse blownno voltage in the AC main etc.

Harmonic DistortionIt is the deviation of the wave shapefrom a pure sine wave.

Frequency instability and Noise aresome of the other problems which maycause havoc to the computer system.

UPS can be broadly classified into twocategories.

• Rotary type

• Static type

Rotary TypeRotary type is the earliest type of UPS. Nowadays this kind of UPS is replacedby the static type because of its disadvantages like huge size, lot of noise andthe need for regular preventive maintenance. Even though it is outdated, thiskind of UPS is used in some of the bigger computer installations.

It is made up of a DC motor, fly wheel, an AC generator, a battery bank and


POWERFAILURE

Type III

Type II SAG ORUNDERVOLTAGE

OSCILLATORYTRANSIENT

TYPE I

HARMONICS

SPIKE ORIMPLUSETRANSIENT

EMI ORRFI

NORMAL VOLTAGE

Fig. 17.3 AC Voltage

SURGE OROVERVOLTAGE


241

a battery charger. The DCmotor and AC generator arecoupled to the same shaftwith a flywheel in betweenthem. The AC mains isstepped down, rect ifiedfiltered and supplied to theDC motor (simultaneouslycharging the batter). So theDC motor and the ACgenerator will be runningand the generator output isgiven to the equipment.When the AC mains fail the

DC motor will keep on running with the help of the battery. There with be nointerruption in the supply to the load during the change over period due tothe huge fly wheel which keeps the generator running without any loss of speed.(Refer to fig. 17.4)

Static TypeThe static type of UPS is known for compactness and silent operation as theymake use of electronic components (nowadays, they are also usingmicroprocessors) thereby offering many functions. There are several differentmajor designs in use for this type. The different types and their basic designprinciples are as mentioned below.

Standby UPS / Standby Power SupplyThe standby UPS is the simplest and least expensive UPS design. In fact, somedon't even consider a standby UPS to really be a UPS, calling it instead astandby power supply (SPS). However, many of the most common consumer-grade devices marketed as UPSes, particularly on the lower end of the budgetscale, in fact use this general design. They are sometimes also called off-line

UPSes to distinguish them from onlineUPSes.

In this type of UPS, the primary powersource is line power from the utility, andthe secondary power source is the battery.It is called a standby UPS because thebattery and inverter are normally notsupplying power to the equipment. The

battery charger is using line power to charge the battery, and the battery and


Transfer Switch Load

DCMotor

Rectif ier

MainAC

Bat tery

F lywheel

AC Generator

Fig. 17.4 Rotary type UPS


Fig. 17.5 Block schematicof a standby UPS

SURGESUPRESSOR FILTER

TRANSFERSWITCH

INVERTERBATTERYBATTERYCHARGER


242

inverter are waiting "on standby" until they are needed. When the AC powergoes out, the transfer switch changes to the secondary power source. Whenline power is restored, the UPS switches back.

While the least desirable type of UPS, a standby unit is still a UPS and willserve well for most users. After all, if standby UPSes didn't work, they wouldn'tsell. For a very critical function, however, such as an important server, they arenot generally used. The issue with a standby UPS is that when the line powergoes out, the switch to battery power happens very quickly, but not instantly.There is a delay of a fraction of a second while the switch occurs, which is calledthe switch time or transfer time of the UPS. While rare, it is possible for theUPS to not make the switch fast enough for the PC's power supply to continueoperation uninterrupted. Again, in practice this does not normally occur ornobody would bother to buy these units. Still, you should compare the unit'stransfer time to the hold (or holdup) time of your power supply unit, which tellsyou how much time the power supply can handle having its input cut off beforebeing interrupted. If the transfer time is much less than the hold time, the UPSwill probably work for you.

Standby UPSes are usually available in a size range of up to about 1000 VA.

Line-Interactive UPS

The line-interactive UPS uses a totally different design than any type of standbyUPS. In this type of unit, the separate battery charger, inverter and sourceselection switch have all been replaced by a combination inverter/converter,which both charges the battery and converts its energy to AC for the outputas required. AC line power is still the primary power source, and the batteryis the secondary. When the line power is operating, the inverter/convertercharges the battery; when the power fails, it operates in reverse.

The main advantage of this design is that the inverter/converter unit is alwaysconnected to the output, powering the equipment. This design allows for faster

response to a power failurethan a standby UPS. Theinverter/converter is alsonormally fitted with circuitryto filter out noise and spikes,and to regulate the poweroutput, providing additionalpower during brownouts andcurtailing output duringsurges.

The line-interactive UPS is an improved design that is commonly used in units


Fig. 17.6 Block schematic ofa line-interactive UPS

TRANSFERSWITCH

BATTERY

INVERTER/CONVERTER

< CHARGING (NORMAL)

DISCHARGING (POWER FAIL) >


243

for home and business use,available in sizes up to 3,000VA or so. It is superior to thestandby UPS, but it still hasa transfer time, and thus doesnot provide protection asgood as the online UPS.

Online ("True") UPS

The online UPS, sometimes called a true UPS, is the best type you can buy.Paradoxically, it is both very similar to, and totally opposite to, the least-expensive type, the standby UPS. It is very similar to it in that it has the sametwo power sources, and a transfer switch that selects between them. It is theexact opposite from the standby UPS because it has reversed its sources: inthe online UPS the primary power source is the UPS's battery, and utility poweris the secondary power source!

Of course, while seeming small, this change is a very significant one. Undernormal operation the online UPS is always running off the battery, using itsinverter, while the line power runs the battery charger. For this reason, this typeof UPS is sometimes also called a double-conversion or double-conversiononline UPS. This design means that there is no transfer time in the event ofa power failure-if the power goes out, the inverter (and its load) keeps chuggingalong and only the battery charger fails. A computer powered by an onlineUPS responds to a power failure in the same way that a plugged-in laptopPC does: it keeps running without interruption, and all that happens is that thebattery starts to run down because there is no line power to charge it.

You may ask yourself, why bother having the secondary power path (the dashedline in the diagram above) if you are always running off the battery anyway?The reason is that this provides backup in the event that the inverter fails orstutters due to some sort of internal problem. While unusual, this can happen,and if it does, the unit will switch to the filtered, surge-suppressed line power.In this event, the matter of transfer time comes into play again, just as it doeswhen a standby UPS reacts to a power failure. Of course, power failures aremuch more common than inverter failures.

There is another key advantage to having the equipment running off the batterymost of the time: the double-conversion process totally isolates the outputpower from the input power. Any nasty surprises coming from the wall affectonly the battery charger, and not the output loads.

Even though it may appear from the schematic diagrams that the online UPSand standby UPS have the same components inside, this is not the case. The


Fig. 17.7 Block schematicof an online ("true") UPS

BATTERYCHARGER BATTERY INVERTER

SURGESUPRESSOR

TRANSFERSWITCH

FILTER


244

distinction is that there is abig difference betweendesigning chargers andinverters that are normallysitting around doing nothingand only run say once a monthfor a few minutes, and

designing ones that are running 24 hours a day for weeks on end. Theadditional engineering and the increased size and quality of the componentscombine to make online UPSes much more expensive than lesser designs. Theyare typically used only for large servers, and for backing up multiple piecesof equipment in data centers. They are available in sizes from about 5,000VA up to hundreds of thousands of VA and even larger.

Aside from the cost, a disadvantage of the online UPS is its inefficiency. Allthe power going to the loads is converted from AC to DC and back to AC,which means much of the power is dissipated as heat. Furthermore, this ishappening all the time, not just during a power failure, and while runningequipment that draws a lot of power. To combat this shortcoming, a new designcalled a delta-conversion online UPS was created. "Delta" is the scientific termoften used to refer to the differential between two quantities. In this design, thebattery charger is replaced with a delta converter. Instead of providing all ofthe output from the battery under normal circumstances, some of it is provideddirectly by the delta converter from the input line power. In the event of a powerfailure, the delta converter stops operating and the unit acts like a regulardouble-conversion online UPS, since the inverter is also running off the batteryall the time.

This is a new design and is also available only in large UPSes (over 5,000VA). They can result in substantial energy savings costs for large units.

Common Specifications of UPSSome of the more common specifications that one will find associated withUPSes are as follows.General:UPS Type: The general design of the UPS. Very important to check this first.Load Rating: The nominal maximum capacity of the unit in VA. Many units willalso specify explicitly the W rating of the unit; otherwise you need to determinethe UPS's power factor from the manufacturer to properly determine sizing.

Input Specifications:Input Voltage: Nominal and actual allowable range specifications. Make sureone is getting the right model for the requirement.


Fig. 17.8 Simplified blockschematic of a delta-conversion online UPS.

DELTACONVERTER

INVERTERBATTERY


245

Nominal Frequency: Generally either 50 or 60 Hz. Some models willautomatically handle either.

Input Connection: The type of plug the power cord uses; very important forlarger units.

Output Specifications:Output Voltage: Nominal and actual range specifications will be provided.Nominal should be the same as the nominal input voltage.

Output Waveform Type: Whether the unit produces a sine, square, or modifiedsquare output waveform.

Transfer Time: An important specification is the typical and/or maximum valuesfor the time required for the UPS to switch from line to battery power. For atrue on-line UPS this will be zero. For stand-by units it will normally be a fewmilliseconds.

Battery Specifications:Battery Type: The type of battery and whether it is user-replaceable.

Battery Capacity: Battery capacity in Ah. (Ampere per hr.).

Typical Battery Life: Number of years the battery is expected to last, on average,in average use.

Typical Run Time at Full Load: If the unit powers a load with a VA rating equalto its maximum load, the expected number of minutes of run time. Typical RunTime at Half Load: If the unit powers a load with a VA rating of half itsmaximum load, the expected number of minutes of run time.

Typical Recharge Time: How many hours it takes to fully charge a dischargedbattery from line power.

Battery Expansion: What sort of expansion features the UPS has, and if so, howthey work.

OtherIndicators and Alarms: A short listing of the indicator LEDs on the unit, andconditions which trigger alarms.

Control and Monitoring Hardware and Software: A brief description of anyincluded or optional control and monitoring systems, including a specificationof the interface types supported by the unit.

Certifications: Which certification bodies have approved the unit.

Warranty: Warranty period in years.


246

.

Computer Mouse

247


Mouse is an input device used to communicate with the PC. This device is usedto operate a modern PC with a GUI (graphical user interface) like windowsetc. also to move the cursor around on a CRT screen to make drawings orexecute commands by selecting a command from a menu.

The mouse was invented in 1964 by Douglas Englebart, who at the time wasworking at the Stanford Research Institute (SRI), a think tank sponsored byStanford University. The mouse was officially called an X-Y Position Indicatorfor a Display System. Xerox later applied the mouse to its revolutionary Altocomputer system in 1973.

In 1979, several people from Apple-including Steve Jobs, who was headingApple at that time-were invited to see the Alto and the software that ran thesystem. Steve Jobs was blown away by what he saw as the future of computing,which included the use of the mouse as a pointing device and the GUI(graphical user interface) it operated. Although Xerox released the Star 8010computer that used this technology in 1981, it was expensive, poorly marketed,

and perhaps way ahead of its time. Apple released theLisa computer, its first system that used the mouse, in1983. It was not a runaway success, largely becauseof its big price, but by then Jobs already had Appleworking on the low-cost successor to the Lisa, theMacintosh. The Apple Macintosh was introduced in1984. Although it was not an immediate hit, theMacintosh has grown in popularity since that time.Certainly the Macintosh, and now Microsoft Windowsand OS/2, have gone on to popularize this interfaceand bring it to the legion of Intel-based PC systems.

Mice come in various shapes and sizes and fromdifferent manufacturers but the largest manufacturersof mice are Microsoft and Logitech.

Computer Mouse

CMS COMPUTER

INSTITUTE

18PC ENGINEERING

Fig. 18.1 The operation of amechanical mouse.

Two rollers mounted at 900

that roll when ball moves

Buttons

Case

Buttonswi tches

To computer

Ball that moveswhen you movethe mouse

Roller motiondetector

Circuitry thattransmits rollermotion informationand switchdepression tocomputer


Computer Mouse

248


The Mouse consists of differentcomponents as follows.

• A housing that you hold in yourhand and move around on your desktop.

• A roller ball that rotates as you movethe mouse

• Several buttons to make selections.

• A cable for connecting mouse to thePC

• An interface connector to attach themouse to the PC

The housing, which is made of plastic, consists of very few moving parts. Ontop of the housing, where your fingers normally rest, are buttons. There mightbe any number of buttons, but in the PC world, typically only two exist. Ifadditional buttons or a wheel are on your mouse, specialized driver softwareprovided by the mouse vendor is required for them to operate to their fullpotential. Although the latest versions of Windows, Windows Me, and Windows2000 support scrolling mice, other features supported by the vendor stillrequire installing the vendor's own mouse driver software.

Mouse Interface TypesThere are many ways that mice and trackballs are interfaced to a computer.Serial Bus, PS/2 and USB. Serial mice connect to a RS-232-type serial port suchas COM1 on the computer. Bus mice use an interface board which plugs intoa slot in the motherboard of the computer. PS/2-type computers have a directrear panel input especially designed for mice and other “pointer”-type devices.

Bus Mouse: Mice, which are serial devices, typically plug into a serial port.However, you also can purchase bus mice, which use an interface card thatyou insert into an expansion slot instead of the standard RS-232C serial port.Because bus mice do not use serial ports, they can be a useful alternative whenyour serial ports are already being used. They do, however, require anexpansion slot to accommodate the interface card. This type of connection hasnow become absolute.

SerialA popular method of connecting a mouse to older PCs is through the standardserial interface. As with other serial devices, the connector on the end of themouse cable is typically a 9-pin female connector; some very old mice useda 25-pin male connector. Because most PCs come with two serial ports, a serialmouse can be plugged into either COM1 or COM2. The device driver, when


Fig. 18.2 Inside of anMechanical Mouse

Computer Mouse

249


initializing, searches the ports to determineto which one the mouse is connected. Somemouse drivers cannot function if the serialport is set to COM3 or COM4, but mostnewer drivers can work with any COM port1-4. Because a serial mouse does notconnect to the system directly, it does notuse system resources by itself. Instead, theresources used are those used by the serialport to which it is connected. For example,

if you have a mouse connected to COM2, and if COM2 is using the defaultIRQ and I/O port address range, both the serial port and the mouse connectedto it use IRQ3 and I/O port addresses 2F8h-2FFh.

PS/2The disadvantage of serial mouse is that if it is attached to serial port of thePC it is difficult to attach other multiple serial devices like serial printers,modems since one of the serial port is used by the mouse.

Most newer computers now come with a dedicated mouse port built into themotherboard. This practice was introduced by IBM with the PS/2 systems in1987, so this interface is often referred to as a PS/2 mouse interface. This termdoes not imply that such a mouse can work only with a PS/2; instead, it meansthe mouse can connect to any system that has a dedicated mouse port on themotherboard.

A PS/2 mouse does not require any slot to be used for a bus card nor doesit require a serial port to be connected to the main computer system it is aspecial mouse port for connecting the mouse. The circuitry to control the mouseis directly built into the motherboard of the PC but in case of failure cannotreplace the circuitry easily.

USBThe extremely flexible USB port is increasingly being used for mice as well askeyboards and other I/O devices. Compared to the other interfaces, USB mice(and other USB pointing devices such as trackballs) have the followingadvantages:

1. Mice with the most advanced features are sometimes made especially forthe USB port. One example is the Logitech iFeel mouse, the first mousewith an optical sensor plus force feedback. It vibrates gently as you movethe mouse over clickable buttons on Web pages, software menus, and theWindows desktop, and it's made especially for USB.

2. USB mice and pointing devices, similar to all other USB devices, are hot-


Fig. 18.3 Bottom side of theMechanical Mouse

Computer Mouse

250


swappable. If you like to use a trackball, and your computing partnersprefer mice, you can just lean over and unplug the other users' pointingdevice and plug in your own, or move it from PC to PC. You can't do thatwith the other port types.

3. USB mice can be attached to a USB hub, such as the hubs contained insome USB keyboards, as well as standalone hubs. Using a hub makesattaching and removing your mouse easy without crawling around on thefloor to reach the back of the computer.

WORKING OF A MECHANICAL MOUSEThe Mechanical Mouse: You use a mouse by moving it around on the tableor mouse pad. This motion is detected and sent to your computer. In amechanical mouse, the motion is mechanical and involves the movement ofparts.

A small ball in the base of the mouse rolls as you move the mouse across asurface. This ball is commonly made from soft rubber. When you push themouse across the desk, friction makes the ball roll inside its housing. Withinthe ball’s housing are two rollers, which are often metal. The rollers are usuallymounted at 90-degree angles to each other. As the ball rolls, it rubs againstthese rollers and rolls them too. Although the rubber ball can roll in anydirection, the metal rollers can roll only clockwise or counter-clockwise. Therollers translate the ball’s motions into movement in two perpendicular (X andY) directions. If you move the mouse exactly horizontal, you move only the rollerthat shows the X-direction movement. If you move the mouse exactly vertical,you move only the roller that shows the Y-direction movement.

These rollers are usually connected to small disks with shutters that alternatelyblock and allow the passage of light. Small optical sensors detect movementof the wheels by watching an internal infrared light blink on and off as theshutter wheel rotates and "chops" the light. These blinks are translated into

movement along the axes which are then convertedinto electronic pulses which are sent to the PC.

OPTICAL MOUSESome of the early mice made by Mouse Systems anda few other vendors used a sensor that required aspecial grid-marked pad. Although these mice werevery accurate, the need to use them with a pad causedthem to fall out of favor. Microsoft's IntelliMouse Explorerpioneered the return of optical mice, but with adifference. Like the old-style optical mice, the

IntelliMouse Explorer uses optical technology to detect movement, and it has


Fig. 18.4 Bottom of theLogitech iFeel optical mouse

Computer Mouse

251


no moving parts itself (except for the scrollwheel and buttons on top). The Explorermouse needs no pad; it can work on virtuallyany surface.

This is done by upgrading the optical sensorfrom the simple type used in older opticalmice to a more advanced CCD (chargecoupled device). This essentially is a crudeversion of a video camera sensor that detectsmovement by seeing the surface move underthe mouse. An LED is used to provide light

for the sensor. The IntelliMouse Explorer is just the first of a growing family ofoptical mice made by Microsoft. (the IntelliMouse Optical and WheelMouseOptical are less expensive versions.) Not to be outdone, Logitech & the othermanufacturers also started offering their optical mouse as well.

Their versatility and low maintenance (not to mention that neat red glow outthe sides!) make optical mice an attractive choice, and the variety of modelsavailable from both vendors means you can have the latest optical technologyfor about the price of a good ball-type mouse.

The Trackball: A trackball is comparable to a mechanical mouse in opera-tion. You use a mechanical mouse by moving it across a surface. Thismovement causes a ball in the mouse to move; the ball’s motion is detectedand transmitted to the PC. With some imagination, you can view a trackballas an upside down mechanical mouse. Instead of moving the mouse to rollthe ball, you actually roll the ball yourself with your hand. The trackball’smotion is detected inside the case by the equivalent of two rollers which aremounted at right angles to each other. The ball’s motion is translated intomotion in the X - direction and the Y-direction, and any movement is trans-mitted to the PC for processing. This is used in Laptop.

Infrared Wireless Mouse: Although most mice are attached to the serialport via a cable, some mice use infrared transmission to send the codes toa receiver that is attached to your serial port. The infrared mice are cordlessin that they do not have a cable that attaches the mouse portion to the serialport. The infrared detector, however, is normally attached to the serial portby a cord. The electronics inside the mouse also detects when you press amouse button. This detection is similar in all types of mice. Infrared mousecommunicates with receiving unit connected to the main system unit usinginfrared light. As the infrared light cannot pass through objects it requires aninfrared mouse to be in direct line of sight with the receiving unit connectedto the PC.


Fig. 18.5 A typicaltrackball.

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When you buy a mouse or trackball, it usually comes with a diskful of programsand a fairly large instruction manual. Included on the disk are the mousedrivers, typically called MOUSE.COM or MOUSE.SYS. You install one of thesedrivers to allow application programs to interface with the mouse. To installthe standard mouse driver, MOUSE.COM, you simply copy the file to the DOSsubdirectory on your hard disk and insert the command MOUSE in yourAUTOEXEC.BAT file. To use the alternate driver MOUSE.SYS, you copy this fileto the DOS subdirectory on your hard disk and insert the statement device =mouse.sys in your CONFIG.SYS file. Either of these methods will load themouse driver automatically when you boot up the system.

Troubleshooting Mouse

1. Make sure the mouse is plugged in securely.

2. Check the driver. Is the mouse driver set up correctly? Is it there in the firstplace?

3. Clean the mouse ball and roller assembly and shake any debris off themouse pad.

4. Check the interface at the end of your mouse cable and at the motherboard,whether it is USB, PS/2, or the serial port. See if there are any obviousproblem such as bent pins (for PS/2 and serial port mice only) that canbe straightened.

5. Ensure that Windows recognizes the mouse and that it is listed in DeviceManager as properly installed. If not then check for any interrupt conflictswhich normally do not occur while using PS/2 port, but while using serialport there are chances of conflicts where one has to assign a separateinterrupt which is unused.

If all this fails, and your computer is not the culprit, you'll need to replace yourmouse.

LAB EXERCISE 18.1 : Mouse Button options and parts identification

Objective: To be familiar with the different internal parts of the mouse as well aswith the mouse properties.

Tasks:1. Check the different parts inside the mouse such as the sensors, the interface type,

the rollers etc. in a mechanical mouse.2. Change the default button for selecting and dragging from the right to the left

button of the mouse.3. Change the double clicking speed to the slowest and try using the mouse.

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KeyboardThe keyboard is a peripheral device which is directly connected on to themotherboard (system board) and it is the only device through which aprogrammer or user can communicate with the CPU as well as with all theperipheral devices attached to it. Through the keyboard you can input programsor data into the machine; it is almost impossible to use a computer withouta keyboard.

The keyboard is basically a set of switches (much like a typewriter), connectedin the form of a matrix, surrounded by electronic circuits which monitor thekeymatrix that continuously scans the keys to recognize key action and generatea scan code.

Types of KeyboardsSerial and Parallel keyboards.

Serial KeyboardIt is a keyboard which outputs the data in serial form, i.e. bit by bit. Thecomputer converts the serial data into parallel 8-bit data. The advantage ofsuch keyboards is that they use only single line to transmit the data.

Parallel KeyboardIt is a keyboard which outputs all the 8-bits at a time in a parallel form. Allthe bits are sent simultaneously on different lines. In this fashion the transmissionis faster but it needs a thicker cable with more number of wires.

In PCs we always use serial keyboards. Hence we will be concentrating on theserial keyboard and its electronic circuit with different types of key switches.

Board SwitchesThere are many different types of key switches. Some of the most commonlyused ones are• Mechanical keyswitches• Membrane keyswitches

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• Capacitive keyswitches• Hall effect keyswitches• Reed Relay keyswitches

The first three of these are most commonly used in keyboards.

Functioning of the KeyboardThe processor in the original PC keyboard was an Intel 8048 microcontrollerchip, but newer keyboards often use an 8049 version that has a built in ROMor other microcontroller chips compatible with the 8048 and 8049.

A keyboard consists of a set of switches mounted in a grid or array called thekey matrix. When a switch is pressed, a processor in the keyboard itselfidentifies which key is pressed by identifying which grid location in the matrixshows continuity. The keyboard processor also interprets how long the key ispressed and can even handle multiple keystrokes at the same time. A 16-bytehardware buffer in the keyboard can handle rapid or multiple keystrokes,passing each one in succession to the system.

When you press a key, in most cases the contact actually bounces slightly,meaning that there are several rapid on-off cycles just as the switch makescontact. This is called bounce, and the processor in the keyboard is designedto filter this or debounce the keystroke. The keyboard processor must distinguishbounce from a double key strike actually intended by the keyboard operator.This is fairly easy.

The keyboard's built-in processor reads the key matrix, debounces the keypresssignals, converts the keypress signals into appropriate scan code, and transmitsthe code to the motherboard. The processors built into the keyboard containtheir own RAM, possibly some ROM, and a built-in serial interface.

In an AT-type keyboard design, the keyboard serial interface is connected toa special keyboard controller on the motherboard. This is an Intel 8042 alsoknown as Universal Peripheral Interface (UPI) slave microcontroller chip in theoriginal AT design. This microcontroller is essentially another processor thathas its own 2K of ROM and 128 bytes of RAM. Some systems may use the 8041or 8741 chips, which differ only in the amount of built-in ROM or RAM, whereasother systems now have the keyboard controller built into the main systemchipset.

These keyboard output values are interpreted by the keyboard circuit as twodifferent logical conditions—key being open and key being close.

Membrane SwitchA membrane keyboard is not a combination of separate switches, instead itis a multi-layer plastic or rubber assembly which is used as keyboard in video


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game machines,calculators, medicalinstruments, cashregisters etc.

As shown in the fig. 19.1in this keyboard, tworubber or plastic sheetare used as row conductor

sheet and column conductor sheet. These row and column sheet are separatedby another sheet with holes at the keytop positions. When the keytop is pressed,it forces the row conductor sheet through the hole to touch the columnconductor sheet.

When the row conductor lines on the row conductor sheet touches the columnline on the column conductor sheet, key contact is made. This is interpretedby the keyboard interface as key closure.

These row and column lines are made on the plastic or rubber sheet usingsilver or some other conductor ink for each row and column of keys on thekeyboard. This keyboard can be made very thin, as a completely sealed unitwhich makes it useful in some of the above mentioned applications.

Typematic FunctionsIf a key on the keyboards is held down, it becomes typematic, which meansthat the keyboard repeatedly sends the keypress code to the motherboard. InAT-style keyboards, the typematic rate is adjustable by sending the keyboardprocessor the appropriate commands. This is not possible for the earlier PC/XT keyboard type because the keyboard interface is not bidirectional.

Keyboard InterfaceThe interface between the keyboard cable and the system unit isthe keyboard interface. This is a DIN (or mini-DIN if it's a PS/2)plug that has five (or six, for mini-DIN) pins. Fig. 19.2 shows theconnector on the system unit side.All together there are four lines (wires) used for interfacing thekeyboard with the system motherboard. They are :

• Keyboard data (KBDATA) • Keyboard clock (KBCLK)

• DC source (+5V Vcc) • DC ground (0V GND)

The Universal Serial Bus (USB) interface is becoming more popularfor keyboards, and some models may, in fact, require you to use a USB portunless you have a USB-to-PS/2 adapter to make the USB keyboard compatiblewith the PS/2 keyboard port. The Microsoft Natural Keyboard and several

Fig. 19.2 An old-style DINkeyboard connector withfive pins (top). PS/2 mini-DINkeyboard connector with sixpins (bottom)



Key Top

Row Conductor Column Conductor

Top Sheet

Row Conductor Sheet

Sheet with Hole

Column Conductor Sheet

Fig. 19.1 Membrane typekeyboard switch


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Microsoft mice are examples of devices that are USB by design, although someversions may include a USB-to-PS/2 adapter with the product. USB deviceshave several benefits, which mostly derive from USB being a newer, fastertechnology. A USB connection is faster than the other, older I/O ports on yourcomputer, such as COM and parallel ports. In addition, a USB device doesn'trequire special device drivers for it to operate.

The primary keyboard types are as follows:

• 101-key Enhanced keyboard

• 104-key Windows keyboard

• 83-key PC and XT keyboard (obsolete)

• 84-key AT keyboard (obsolete)

This section discusses the 101-key Enhanced keyboard and the 104-keyWindows keyboard, showing the layout and physical appearance of both.Although you can still find old systems that use the 83-key and 84-key designs,these are rare today. Because all new systems today use the 101- or 104-keykeyboard design, these versions are covered here.

Enhanced 101-Key (or 102-Key) KeyboardIn 1986, IBM introduced the "corporate" Enhanced 101-key keyboard for thenewer XT and AT models. The layout of this universal keyboard was improvedover that of the 84-key unit, with perhaps the exception of the Enter key, whichhad increased in size, reverted to a smaller size. The 101-key Enhancedkeyboard was designed to conform to international regulations andspecifications for keyboards. In fact, other companies, such as Digital EquipmentCorporation (DEC) and Texas Instruments (TI), had already been using designssimilar to the IBM 101-key unit. The IBM 101-key units originally came inversions with and without the status-indicator LEDs, depending on whether theunit was sold with an XT or AT system.

With the replacement of the Baby-AT motherboard and its five-pin DIN (anacronym for Deutsche Industries Norm) keyboard connector by ATXmotherboards, which use the six-pin mini-DIN keyboard connector, virtually allkeyboards on the market today come with cables for the six-pin mini-DINconnector introduced on the IBM PS/2s. Although the connectors might bephysically different, the keyboards are not, and one can either interchange thecables or use a cable adapter to plug one type into the other; some keyboardsyou can buy at retail include the adapter in the package.

The 101-key keyboard layout can be divided into the following four sections:

• Typing area

• Numeric keypad


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• Cursor and screen controls

• Function keys

The 101-key arrangement is similar to the earlier keyboard layout, with theexception of the Enter key. The Tab, Caps Lock, Shift, and Backspace keys havea larger striking area. Ctrl and Alt keys are on each side of the spacebar.

The typing area and numeric keypad have home-row identifiers for touchtyping. The cursor- and screen-control keys have been separated from thenumeric keypad, which is reserved for numeric input. A division-sign key (/) andan additional Enter key have been added to the numeric keypad.

The Insert, Delete, Home, End, Page Up, and Page Down keys, located abovethe dedicated cursor-control keys, are separate from the numeric keypad. Thefunction keys, spaced in groups of four, are located across the top of thekeyboard. The keyboard also has two additional function keys: F11 and F12.The Esc key is isolated in the upper-left corner of the keyboard. Dedicated PrintScreen/Sys Req, Scroll Lock, and Pause/Break keys are provided for commonlyused functions.

104-Key (Windows 9x/Me/2000) KeyboardWindows 9x and newer versions make this even more of a problem becausethey use both the right and left mouse buttons (the right button is used to openshortcut menus). When Microsoft released Windows 95, it also introduced theMicrosoft Natural Keyboard, which implemented a revised keyboardspecification that added three new Windows-specific keys to the keyboard.

The 104-key layout includes left and right Windows keys and an Applicationkey. These keys are used for operating system and application-level keyboardcombinations, similar to the existing Ctrl and Alt combinations. Therecommended Windows keyboard layout calls for the Left and Right Windowskeys (called WIN keys) to flank the Alt keys on each side of the spacebar, as

well as an Application key on the right of the RightWindows key.

The WIN keys open the Windows Start menu, which youcan then navigate with the cursor keys. The Applicationkey simulates the right mouse button; in most applications,it brings up a context sensitive pop-up menu. Several WINkey combinations offer preset macro commands as well.For example, you press WIN+E to launch the WindowsExplorer application. Table shows a list of all the Windows9x/Me/2000 key combinations used with the 104-keykeyboard.

Fig. 19.3 104-Key Keyboard



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Windows 9x/Me/2000 Key Combinations

Key Combination Resulting ActionWIN+r Runs dialog box

WIN+M Minimize AllShift+WIN+M Undo Minimize All

WIN+D Minimize All or Undo Minimize AllWIN+F1 Help

WIN+E Starts Windows ExplorerWIN+F Find Files or Folders

Ctrl+WIN+F Find ComputerWIN+Tab Cycles through taskbar buttons

WIN+Break Displays System properties dialog boxApplication key Displays a content menu for the selected item

Keyboards with Special FeaturesA number of keyboards on the market have special features not found instandard designs. These additional features range from simple things, such asbuilt-in calculators, clocks, and volume control, to more complicated features,such as integrated pointing devices, special character layouts, shapes, andeven programmable keys.

Cordless KeyboardsSome manufacturers are now making cordless keyboards. These are likeregular keyboards, except instead of having a keyboard cable that runs fromthe keyboard to the PC, they have no cord. The wired interface between thekeyboard and the motherboard is replaced with a wireless one. Two transceivers"talk" to each other over a radio link: one is within the keyboard and wiredto the keyboard's internal controller, and the other is a separate device thatcontains a length of keyboard cable and a conventional keyboard connectorto attach to the PC. They also typically cost more than the corded models.Furthermore, since "cordlessness" is a high-end feature, they are usually high-

end models, making the overall package a bit pricey fora keyboard.

Multimedia and Web-Enabled KeyboardsMany keyboards sold at retail and bundled with systemstoday feature fixed-purpose or programmable hotkeysthat can launch Web browsers, run the Microsoft MediaPlayer, adjust the volume on the speakers, change trackson the CD player, and so forth. You need Windows 98 orbetter to use these hot keys; Windows Me and Windows2000 add additional support for these keyboards.


Fig. 19.4 Microsoft Multimedia keyboard


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Ergonomic KeyboardsA trend that began in the late 1990s is to change the shape of the keyboardinstead of altering the character layout. This trend has resulted in a numberof so-called ergonomic designs. The goal is to shape the keyboard to betterfit the human hand. The most common of these designs splits the keyboardin the centre, bending the sides outward. Some designs allow the anglebetween the sides to be adjusted, such as the now-discontinued Lexmark Select-Ease, the Goldtouch keyboard and the Kenisis Maxim split keyboards. Others,such as the Microsoft Natural keyboard series, PC Concepts Wave, and CirqueSmooth Cat, are fixed. These split or bent designs more easily conform to thehands' natural angle while typing than the standard keyboard.

Troubleshooting KeyboardsWhen a keyboard stops working follow these steps:

• Make Sure it is plugged in. On the back of computers that use PS/2-type connectors are two identical ports: the mouse port and the keyboardport. Make sure the keyboard has been plugged into the correct port. Youwill get an error when turning on the computer if the mouse and/orkeyboard are connected to the wrong port.

• Make sure BIOS and Windows See it. If there is a keyboard failure,you should see a message when your computer boots up. Pay closeattention, and if you see the message, try checking the connection firstbefore you move on to more drastic measures.

If the BIOS doesn't display any errors on-screen (such as Keyboard notpresent or Keyboard failure) when you boot up, make sure Windowsrecognizes your keyboard by checking Device Manager. You can accessDevice Manager in Windows by opening Control Panel and double-clicking the System icon. Select the Device Manager tab in the SystemProperties dialog box. Your keyboard should be listed in the Keyboardcategory. If it is listed, make sure it is the proper make and model.

• Fix Bent Pins: Check your PS/2 type connector that plugs into themotherboard for any bent or missing pins. This often happens if someone(usually children, although adults can do this too if they aren't payingattention) tries to force the connection in the wrong orientation. Whathappens is that the pins that aren't lined up with the correct holes on themotherboard connector get bent back as you force the connection. There'ssimply no place for them to go but sideways. If your pins are bent, carefullystraighten them with a pair of slim, needle-nosed pliers. Be careful not tobreak off the pins as you straighten them.

• Connect it to Another Computer: If you're fortunate enough to havemore than one computer in your home (most business have several, youcan try swapping keyboards with a machine that you know isn't suffering


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LAB EXERCISE 19.1 : Keyboard Shortcuts

Objective: To be familiar with the different types of keyboards and to be able touse the features in the internet keyboards as well as be familiar with keyboard shortcuts.

Tasks:1. Differentiate the keyboards into different types depending upon the features.2. After loading the drivers, try opening and closing the CD-ROM on a multimedia

keyboard.3. Use the keyboard shortcut to minimize or maximize a window.4. Use the keyboard shortcut to run through the different open windows in the

taskbar.

keyboard problems. If the new keyboard doesn't work on the machineyou're testing, you may have a faulty keyboard connection on themotherboard.

• Check the keys: If only one key is malfunctioning, check the spring underthe key to see whether it springs up and down, as a key should. Removethe key by grabbing it with your fingers and pulling up. For the tough keys,fashion a hook from a paper clip or, again, use a chip puller. You will seea spring under the key. Replace the keytop and see whether the problemgoes away. If not, try pulling the spring our just a little. Then replace thekeytop.

Some keyboards use rubber cups instead of springs. Either way, the cup orspring is designed to keep the keys from being "on" all the time.

• Test Pin Voltages: If you hold a DIN so that the pins are at the top andcount from left to right, the pins are numbered 1, 4, 2 5, and 3; the number2 pin is at the top-centre point. Holding a mini-DIN with the single groovein the connector at the top, and starting from the bottom left and movingclockwise, the pins are numbered 1,3,5,6,4, and 2; the groove is betweenpins 5 and 6.The voltage between pin 4 and each of the other pins should be in the rangeof 2-5.5 volts DC. If any of these voltages are wrong, the problem probablylies in the PC - the system board in particular. If they're okay, the problemis probably in the keyboard.

• Check the Cable Continuity: Next, test continuity of the cable. Turn thekeyboard upside down so that the cable is coming out of the back of thekeyboard, to the right. Remove the two screws. The bottom plate will swingback and up for removal.

You will now see that the cable splits to a single wire, which is grounded tothe bottom plate. You'll also see a cable with a flat-jaw connector. Push apartthe jaws of the connector to release. You can then use an ohmmeter/ multimeterto test each of the five wires for continuity.

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ScannerA scanner is the eye of a computer that allows you to capture information likepictures and text and convert it into a digital format that can be edited on yourcomputer. With the prices and the interfaces used by scanners seeing verydrastic changes, there are many to choose from with varied and very interestingfeatures and applications.There are five popular types of scanners you can install on your system:

Flatbed scanners: The most popular type of scanner for home use is theflatbed, or desktop, scanner. It makes it easy to scan papers, books and anyother item that you can flat between a glass bed (plate) and the scanner's topcover. The image is scanned via a scan head that moves across the face ofthe original document. Most flatbed scanners scan in color.

Sheet-fed scanners: Sheet-fed scanners are like flatbed scanners, except thescan head is fixed and the original document moves across the head. Whileflatbed scanners can scan just about any item that can fit on the glass plate,including three-dimensional objects, sheet-fed scanners can scan only flatpieces of paper. In addition, many sheet-fed scanners scan only in black and

white.

Combo scanner/printer/fax: A very popular optionin home offices and small offices is the "all-in-one"machine that scans, prints, faxes, and copies. Theseunits, popularized by Hewlett-Packard, effectively mergea black-and-white sheet-fed scanner with an inkjet orlaser printer and a fax machine. You feed the originaldocuments into a slot, just as you do with a freestandingsheet-fed printer, and then the scan head moves acrossthe document.

Handheld scanner: A handheld scanner is kind of amanually controlled flatbed scanner. In this case, the

Scanner

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original document is placed on a flat surface (like a desktop), and youmanually move the scanner across the face of the document. In essence, yourarm becomes the moving scan head. This type of scanner doesn't deliver thebest quality, but it is convenient-and very portable. Unfortunately, portablescanners have proved particularly problematic and thus aren't in widespreaduse today.

Drum scanners: If you want high-quality black-and-white or color scans, likethe kinds required by the magazine, newspaper, and book publishing industries,you need to go all the way up to an expensive drum scanner. This type ofscanner mounts the original document on a rotating glass cylinder calleddrum. At the centre of the cylinder is a sensor that splits light bounded of thedocument into three beams. Each beam is then sent through a color filter intoa photomultiplier tube (PMT), where the light is changed into an electricalsignal. Drum scanners are much more expensive than consumer-quality flatbedscanners, and they typically connect to a computer system via a SCSI interface.

Whatever method is used to scan a source document, a digital image of thatdocument is then created. That digital image can be saved in a variety ofgraphics file formats. (TIF, BMP, JPG, and so forth), or the text information canbe extracted (via optical character recognition technology) and saved as a textfile.

Scanner WorkingAs shown in fig. 20.2 most flatbed scanners are composed of the followingparts:

• Glass bed (or plate), on which the source document is placed facedown.

• Lamp, used to illuminate the source document

• Mirrors, used to reflect the image of the source document

• Filters, which adjust the image of the source document

• Lens, used to focus the image of the source documentonto the CCD array

• CCD array, used to turn reflected light into an electricalcharge

• Scan head, which contains the CCD array, mirrors,lens, and filter

• Stabilizer bar, to which the scan head is attached.

• Belt, attached to the stepper motor and used toadvance the stabilizer bar

• Stepper motor, used to drive the stabilizer barFig. 20.2 The major parts ofa flatbed scanner


Cover

CCDarray

Lamp

Scanbed

LensMirrors

Glass bed

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• Cover, used to provide a uniform background for the scanned document-ad to keep you from being blinded by the scanner lamp.

You prepare for a scan by placing the source document facedown on a glassplate. You then close the scanner's cover, which provides a uniform backgroundthat the scanner software can use as a reference point for determining the sizeof the scanned document.

When you press the button to start the scan, the lamp lights to illuminate thesource document, and the stabilizer bar is sent rolling from one end of thedocument to the other. As the scan head-which is attached to the stabilizer bar-travels across the face of the document light is reflected off the document,through a series of mirrors, filters, and lenses, and then onto the CCD array.

The CCD is actually a collection of light-sensitive diodes, called photosites.The photosites convert the reflected light into an electrical charge; since eachphotosite is sensitive to slight variations in light, the brighter the light that hitsa photosite, the greater the electrical charge generated.

Most low-cost scanners use a single pass to scan the original document, whilesome higher-end models used a three-pass method. In the single pass method,the lens splits the image into three identical versions of the original. Theseimages are then passed through three color filters (red, green, and blue) toseparate sections of the CDD and combined to create a single full-colorimage. In the three-pass method, each pass of the scan head uses a differentcolor filter (red, green, or blue) between the lens and the CCD array; assemblingthe three filtered images results in a single full-color image.

Some inexpensive flatbed scanners use a contact image sensor (CIS) insteadof a CCD array. The CIS replaces the entire CCD/mirror/filter/lens/lampmechanism with rows of red, green, and blue LEDs. The image sensor is placedvery close to the glass plate, and the LEDs combine to provide a bright whitelight. The illuminated image is then captured by the same sensors.

Scanner/Computer InterfaceThere are three main interfaces used to connect scanners to personal computers:USB, parallel, and SCSI.

USB: The USB interface is the easiest way to connect a consumer-grade flatbedscanner. Just connect a cable from your scanner's USB output to a USB intoinput on your PC. Since USB is a "hot" interface, you don't have to turn off yourcomputer to make your connections, and Windows should recognize the newdevice as soon as it's plugged in and turned on.

Parallel: The parallel interface is used by almost all sheet-fed and all-in-onescanner, as well as some older flatbed units. In the case of sheet-fed and flatbedscanners, the parallel connection is shared with a printer; the printer typically

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plugs into the back of the scanner (or into a special Y cable), and the scannerthen interfaces directly to the PC. This type of connection can be problematic,especially if you try to use the scanner and printer at the same time. (You can't).However, if you're connecting an all-in-one scanner/printer/fax/copier, theparallel connection is the only way to go, and you shouldn't encounter anyproblems.

SCSI: The faster SCSI interface is used for the high data transfer rates inherentwith drum scanners. Most drum scanners include a dedicated SCSI card youhave to install in your computer, although many also let you use a standardSCSI controller.

Determining Image QualityMost flatbed scanners deliver a resolution of at least 300 x 300 dpi. The dpiis determined by the number of sensors in a single row of the CCD or CIS array(which determines the x-direction sampling rate) and by the precision of thestepper motor ( which determines the y-direction sampling rate).

Resolution can be artificially enhanced by the scanning software used byscanner. Some software program interpolate extra pixels between the actualpixels, thus increasing the apparent resolution. For eg., software that puts oneextra pixel between each real pixel turns a 300 x 300 dpi scanner into a virtual600 x 300 scanner.

Managing Scanned File SizeThe higher the resolution of your scans, and the greater the bit depth, the largerthe file sizes. For eg., if you scan a 5 x 7 photograph at 600 x 1200 dpi (andsave it in the details BMP format) you end up with a whopping 74MB file.

It's always a good idea to manage the file sizes of your scanned images. Youcan do this in several ways.

First, don't use the BMP format! Bitmapped files are the least efficient file types,period. Instead, configure your scanner acquisition software to use either theTIFF (if you intend to print the final file) or JPG (if you intend to use the fileon the Internet) formats.

Second, if you don't need the full resolution, don't use it. For most purposes,300 x 300 dpi is just fine.

Next, if you don't need a big picture, shrink the scanned image. If that 5 x 7"photo you've scanned only needs to display as a 2.5 x 3.5 image in a newsletteror on a Web page, use your image-editing software to resize the pictureaccordingly.

In addition, you can usually reduce the color depth without affecting the waya picture looks. If you scanned at 24-bit resolution, you may be able reduce

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the color depth (within your image-editing program) to 8-bit or 16-bit color,especially is the scanned image is for online use.

Optical Character RecognitionMany scanners also include optical character recognition (OCR) software,which enables you to convert scanned text into computer-based text. This wayyou can scan a document and import it directly into a word processor (suchas Microsoft Word) as editable text, rather than as a graphic.

Most current OCR software does a fairly good job of translating printedcharacters to digital characters, although you'll still need to clean up anymisinterpretations. The cleaner the scan, the better the job the OCR softwaredoes, so start with a clean original and make sure you take a good, high-contrast scan.

Working with the Scanner Installation Wizard

Before trying to use the Scanner and Camera Installation Wizard, you shouldfirst try connecting your scanner to your computer and turning it on. If Windowsrecognizes your scanner and installs the appropriate driver, you don't need touse the wizard. The Scanner and Camera Installation Wizard helps you toinstall drivers for older scanners and cameras-and some networked scanners-that are not automatically recognized by Windows.

To start the Scanner and Camera Installation Wizard

1. Open the Scanners and Cameras wizard by clicking the Start button ,clicking Control Panel, clicking Hardware and Sound, and then clickingScanners and Cameras. If you are prompted for an administrator passwordor confirmation, type the password or provide confirmation.

2. If you don't see your scanner or camera listed, ensure that it is connectedto your computer and turned on, and then click Refresh.

3. If your device still isn't listed, click Add Device to start the Scanner andCamera Installation Wizard, and then follow the instructions to install thenecessary drivers.

Note

The wizard will ask you to select your scanner from a list. If your scanner isn'tlisted, you will need to obtain drivers for it, either from the manufacturer'swebsite or from a disc provided by the manufacturer, and then click Have Diskwhen asked to choose your scannerTo add a network scanner

Before you begin, make sure that you know the scanner model and manufacturer

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name, and that your computer is connected to the network. Windows willautomatically detect the scanner and add it to the Network folder on yourcomputer.

1. Open Network by clicking the Start button , and then clicking Network.

2. Locate the scanner, right-click it, and then click Install.

3. Follow the instructions to finish adding the network scanner.

Note

If Windows could not add the scanner to your Network folder automatically,check the information that came with the scanner to see how to install it, orcontact a system administrator.To remove a scanner

You must be logged on as an administrator to perform these steps.

To stop using a scanner, you can unplug it from your computer at any time.You don't need to uninstall the driver. If you want to uninstall the driver andany programs that came with the scanner, follow these steps:

1. Open Device Manager by clicking the Start button , clicking Control Panel,clicking System and Maintenance, and then clicking Device Manager. Ifyou are prompted for an administrator password or confirmation, type thepassword or provide confirmation.

2. To see scanners that have been added to the computer, double-clickImaging devices.

3. Right-click the scanner name, and then click Uninstall.

Steps for Connecting a Scanner to PC

1. Shutdown your computer and turn-off your computer and printer (Assumingthat you have a printer connected to your parallel port)

2. Unlock the scanner. (The scanner has a carriage lock that protects theinternal components from damage during shipment)

3. Disconnect the end of the printer cable to the back of the scanner. Use theport labelled for connecting the printer. The printer is now connected to thescanner.

4. Connect the scanner cable to the parallel port on the computer

5. Connect the other end of the scanner cable to the back of the scanner. Usethe port labelled for connecting the computer.

Connect the power cord and turn on your PC, scanner and printer

Scanner

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LAB EXERCISE 20.1 : Scanning through Flatbed scanner

Objective: To be familiar with the flatbed scanner's internal parts as well as thescanning software present along with the scanner.

Tasks:1. Opening an old Flatbed scanner, identify the different internal parts in the scanner

such as the carriage assembly, the mirror set present in the carriage unit, as wellas the heating lamp, the logic board etc.

2. Identify the purpose of the buttons on the scanner.3. Now, after installing the scanning software, scan a page from "cms" book and

send the scanned image to the different editing software options which are madeavailable by the scanning software.

4. Scan the image in the different options available i.e. text, text and image, colorimage, color etc.

Scanner

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PrinterCMS COMPUTER INSTITUTE

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PrinterPrinters are devices that take digital information generated by a computer andconvert it into a format that is very familiar to us - printed paper.

Printers were primarily aimed at high-speed printing where low running costwas the main factor. These printers consisted of a matrix of pins that could be‘fired’ or actuated as the head was moved across a line, thus generating aseries of characters.

Then, came the inkjet printers. These printers worked on a very novel idea ofspraying tiny dots of ink on paper (or a variety of other media). As thetechnology used for generating these ink dots advanced, the resolution or theclarity of the final image increased to the point at which these printers couldnow generate photo-realistic prints. These printers are one of the best choicesfor both home and office use due to the quality and (depending upon thetechnology) the reasonably low running cost.

The next printer which came in is the laser printer. The laser printer is verysimilar to a copier machine and is amazingly reliable.

It uses a laser beam to generate the prints. The resolution and the print speedsachieved by these printers are higher than those of the other two technologiesby orders of magnitude. The only downside here is the significantly higher costbut nowadays they are becoming cheaper though not as cheap as thedotmatrix and inkjet types.

CLASSIFICATION OF PRINTERSIn general Printers can be classified in two broad categories

1. IMPACT TYPE PRINTERS

2. NON-IMPACT TYPE PRINTERS.

In IMPACT type of printers physical force is applied to get an impression ofcharacter. The printer HEAD presses through an inked ribbon that touches thepaper and leaves the head’s impression over the paper.

Printer

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21PC ENGINEERING



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Examples of these type of printers are:

a) DAISY-WHEEL printers

b) DOT-MATRIX printers

c) LINE printers

In NON-IMPACT type of printers, physical force is NOT appliedto get an impression of character; instead either the IMAGE istransferred to paper electrostatically or ink is sprayed on to paperto form the character. Examples of these type of printers are:

a) INK-JET printers

b) LASER printers

DAISY-WHEEL PRINTERSThe Daisy-Wheel is a small plastic wheel with many spokes, atthe ends of which Raised Image of Characters are provided. Inthis sense they are similar to normal Type-Writers. As the printhead moves across the paper the daisy wheel revolves. A solenoiddriven hammer strikes it as the appropriate character is in frontof the paper. This causes the spoke containing the desired characterto press against ribbon, thus printing it on the paper.

ADVANTAGESThe output of this printer is same as that of normal typewriter, hence it is calledas LETTER QUALITY output.

DISADVANTAGESThey are very slow and noisy. Generally, they are incapable of printinggraphics or different fonts. One can change fonts only by changing wheel.

Dot-Matrix Printers (DMP)Dot-Matrix printers strike the page with small rods (calledneedles) that protrude from the print head. They canprint through multiple layers of carbon (or carbonless)copies, and some business need that capability.

The most expensive part of a dot-matrix printer that diesis the print head. Luckily, almost all dot-matrix printersthese days have a thermistor (basically, a temperaturesensor) that detects when the print head is getting toohot and shuts the printer down until it cools off. To avoidexcess heat buildup around a dot-matrix printer, avoidstacking things around it. Leave a clear path for airflowon all sides.

Fig. 21.1 Daisy-wheelprint mechanism.

Print Arm Side View Print Arm Top View

FlexibleSection

Hub

Print Arm The Print Hammerhas a notch thatpositions the printarm during thestrike

Print Hammer

RigidSectionCarriesType

Daisy-WheelPrint Wheel


Fig. 21.2 DOT Matrix Printer



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Replacing the print head is not economical on many printers because of thehigh price that manufacturers charge for replacements.

In general, DMPs can be characterized by following 5 parameters.

1. No of pins in print head.

2. Characters per second (CPS)

3. Characters per inch (CPI)4. Width of printer (in columns)5. Interface used [parallel / serial]

1. No of pins in print head.To process a character in slices, the pins in the printhead are arranged invertical columns. Most commonly used printers have either 9 pins or 24 pinsin their print head.

In all 9-pin printers, all the 9 pins are arranged vertically in only one column.Examples are EPSON FX-1000, TVSE LSP 100 etc...In 24 pin printers, the pins are arranged in 2 vertical columns, slightlydisplaced from each other as shown. Examples are FUJITSU DL 3400, EPSONLQ1070+

Some odd pin printers are also available for example, the commonly used‘SEIKOSHA’ has 8 pins and all the ‘Philips’ models have 18 pins arranged in2 columns.

In general, there are two modes of printing. a) Draft b) NLQ (Near letterquality). In draft mode, the character is generated by a single pass of the printhead and hence it is faster.

For NLQ print-out, in a 9 pin printer, 2 passes over the same line are madefilling the gaps in between the previous dots. For this the paper is shifted veryslightly.

In a 24 pin printer, since the pins are arranged in 2 vertical columns, slightlydisplaced from each other, 2 passes are not required.

2. Characters per second (CPS) :This parameter indicates how many characters can be printed in onesecond. In a standard way, we tell the CPS for both NLQ and DRAFTmode eg.,For FX 1000,In DRAFT - CPS = 240 char/sIn NLQ - CPS = 40 char/s

Thus we can see that this parameter indirectly tells you about the speedof the printer. The CPS is always greater for draft mode than that for NLQ.Fig. 21.3 Near letter quality

(NLQ) type of printing.


Printed DotsOverlap


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3. Characters per inch (CPI) :This indicates how many characters can be printed in an inch length of aprintable row. Commonly used CPI’s are -10 cpi, 12 cpi or 15 cpi. Normally,the 15 cpi mode or 17 cpi is called as condensed mode.In new printers 20 cpi is also possible.

4. Width of the printer :This indicates the size of printer. The two standard sizes are 80 column and132 column. 80 or 132 column mean that the printer can print 80/132 differentcharacters in one printable line (row). This parameter also indicates the sizeof stationery that will be used with that printer.

5. Interface used :There are two types of interfaces used to communicate with computer.a) Parallel b) Serial

For parallel interface, we use a standard 36 pin centronics interface. Thisinterface has a 25 pin D type female connector on the computer side and 36pin Amphenol type connector to printer side and serial interface we use thestandard 9 pin and 25 pin male on the PC side and 9 pin/26 pin female onthe printer side.

Dot-Matrix Printer Working1. Your PC sends a series of hexadecimal ASCII codes that represent characters,

punctuation marks, and printer movements such as tabs, carriage returns,line feeds, and form feeds, which control the position of the print head inrelation to the paper.

2. The ASCII codes are stored in a buffer, which is a special section of theprinter's random access memory (RAM). Because it usually takes longer fora dot-matrix printer to print characters than it takes a PC and software tosend those characters to the printer, the buffer helps free up the PC toperform other functions during printing. The internal buffer of a dot-matrixprinter generally has only a 7k to 8k capacity. When the buffer gets full,the printer sends an XOFF control code to the computer to tell it to suspendits stream of data. When the buffer frees up space by sending some of thecharacters to its processor, the printer sends an XON code to the PC, whichresumes sending data.

3. Among other codes are commands that tell the printer to use a certain font'sbitmap table, which is contained in the printer's read-only memory chips.That table tells the printer the pattern of dots that it should use to createthe characters represented by the ASCII codes.


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4. The printer's processor takes information provided by the bitmap table foran entire line of type and calculates the most efficient path for the printhead to travel. (Some lines may actually be printed from right to left.) Theprocessor sends the signals that fire the pins in the print head, and it alsocontrols the movements of the print head and platen.

5. Electrical signals from the processor are amplified and travel to the circuitsthat lead to the print head. The print head contains 9 or 24 wires, calledprinting pins, that are aligned in one or two straight lines. One end of eachof the pins is matched to an individual solenoid, or electromagnet. Thecurrent from the processor activates the solenoid, which creates a magneticfield that repels a magnet on the end of the pin, causing the pin to movetoward the paper.

6. The moving pin strikes a ribbon that is coated with ink. The force of theimpact transfers ink to the paper on the other side of the ribbon. After thepin fires, a spring pulls it back to its original position. The print headcontinues firing different combinations of print wires as it moves across thepage so that all characters are made up of various vertical dot patterns.Some printers improve print quality or create boldface by moving the printhead through a second pass over the same line of type to print a secondset of dots that are offset slightly from the first set.

MAJOR PARTS OF A DOT MATRIX PRINTER (DMP)In general any DMP can be divided into 4 major parts.

1. Mechanical Assembly

2. Logic Card

3. Power Supply Card

4. Front Panel

1) The Mechanical Assembly :This is the most important part of a DMP from the troubleshooting point ofview. This is because of 2 reasons:

1. This part is always moving at a faster rate. Hence friction is high.Consequently wear and tear is high.

2. This part is normally open. Hence dust, dirt, paper particles, etc. mayinterrupt its normal operation. It is observed that out of 100 printerproblems, 70-75 problems are related to mechanical assembly.

In general, the mechanical assembly can be divided into following parts:

a) Print head : with cable or without cableb) Carriage and carriage assemblyc) Carriage motor, timing belt/carriage wire.


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d) Sensors Home position and Paper emptye) Platen, line feed gear assembly and line feed motor.f) Leversg) Paper thickness adjustment,h) Frictioni) Plunger (automatic paper loading)j) Ribbon and ribbon gear assembly

k) Tractor assembly

a) The print head :The print head looks as shown in fig. 21.4There are two types of print heads available :With cable and Without cable.

In head with cable, the head cable is directly soldered to theprint head so that if the cable only becomes faulty you have to throw thecomplete head. Hence, it is not preferable. eg., TVSE series except LSP100

In the head without cable, the head cable is connectedto head through a connector. If the cable is gone faulty,then it can be easily replaced. Hence, it is preferred.eg. EPSON series except FX105 MX80

Internal structure of head and how pins arefired:Here, the coil is wound on a ferrous rod. When currentpasses through this coil, the rod gets magnetised andthe metallic base of the pin gets attracted towards it,

moving the pin towards paper and thus ultimately striking ribbon and paper.

b) Carriage and carriage assemblyThis provides the movement for the print head. As isshown in fig. 21.5 it is having a base for head and tworails. Over these rails the base or ‘carriage’ moveshorizontally from left to right and back. The base hasbearings wherever it comes into contact with the rails.

c) Carriage motor, timing belt/carriage wire :Carriage motor is basically a stepper motor. Carriagemotor provides the actual force to move the carriage.This force is converted into the actual motion of carriageusing either the timing belt or the carriage wire.

In FX1000 - Timing beltEX1000 - Carriage wire

Fig. 21.4 Printheadresistance

Printhead # 1 # 2 # 3 # 4 # 5 # 6 # 7 # 8 # 9

(Wireassignment

Coil Resistance :14.8 + 1.4 at 250C(between each dotwire and common)

#7 #5 COM #9 #8

#1 #3 #2 #4 #6


Tab for leftcarriage-stopsensor

Cable StepperMotor

Tab for rightcarriage-stopsensor

Carriage supportRails

Carriage Pulleys

Fig. 21.5 Top View ofprinter carriage mechanism

Fig. 21.6 Top View ofprinter carriage mechanism

IdlerRoller

ToothedBelt

DriveRoller

StepperMotor

CarriageSupport Rails

Carriage




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The tension of the belt/wire is an important consideration whiletroubleshooting.

d) Sensors :1. Home position sensor :The print-head is able to move freely but the controlling BIOSof printer must know its exact position. For this, there should besome ‘reference position’ so that from that position onwards,BIOS can count the exact position of print head.In general, the leftmost position is taken as ‘reference or homeposition’. This must be detected. For detecting it, the homeposition sensor is used. It is nothing but a normal photo detectorcircuit. The carriage has a vertical slit below it. Whenever, it

reaches the leftmost position, the slit blocks the photo emission, thus givinga pulse.

2. Paper empty sensor :The printer should print only when there is paper in front of the print - head.To detect the status of paper a simple mechanical micro - switch is used.

e) Platen, line feed motor and gears :Now, whenever one line is printed, the paper should be moved by somedistance so that the next line will get printed in a intelligible manner. This isperformed using platen and line feed motor and gear assembly. Platen is ahard rubberised rod that provides striking surface for the print-head pins. Linefeed motor is also a stepper motor and its motion is given through line feedgear assembly.

f) Levers :1. Paper thickness adjust lever :This lever is used to adjust the gap between the platen and the print head.Hence, we can use variable thickness stationery like 1, 1+2, 1+4, etc. This levervirtually moves the head back and forth in horizontal plane very slightly.

2. Friction lever :If you are not using continuous stationery i.e. if you are using cut-sheet papers, you must use some mechanism that will move paperwith platen. This friction lever adjusts the friction rollers so thatwhen in friction mode the pressure rollers are very tightly coupledto the platen. In between them the cut-sheet paper is present. Asa result, the paper will move with platen movement.

Print Hammer


Stored Ribbonis folded

Drive Wheel

PressureWheel

PressureSpring

Fig. 21.8 An endless-loopribbon cassette


Fig. 21.7 Friction-Feedmechanism

Spring-loadedBail rollers

Platen DriveGear

Platen

PrintArea

Spring-loadedpressurerollers

StepperMotor

DriveGear

Paper


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TractorPaper

Tractor DriveWheel

Flexible Beltwith TractorPins

PlatenDrive Gear Platen

Idler Gear

Tractor Drive Gear

SquareDriveShaft


Fig. 21.9 Tractor-feedmechanism

g) Ribbon and ribbon gear assembly :Ribbon provides the ink required for printing. Suppose the samearea of ribbon is used for printing, the print quality will go onfading. For this, the ribbon is always moved in one directiononly, i.e. from one side it goes in the box and for other side itcomes out. Inside the box it is re-inked. To move the ribbon inonly one direction while the head is moving in both direction,ribbon gear assembly is used.

h) Tractor assembly :This is used only with continuous stationery which has perforationholes at the side. It is of two types.

1. Push and 2. PullNote: Whenever tractor assembly is being used never put paper in frictionmode.

2) The Logic Card :It is the main printed circuit boardwhich controls the working of theprinter. It is this board which sendsthe appropriate signals to the partsneeded by the printer for printing.It thus co-ordinates between thedifferent actions performed by theprinter.

3) Power Supply Card:This card supplies the powerrequired by the printer for it'soperations. It is thus responsible forconverting the line a.c. voltage intoappropriate d.c. voltages requiredby the different parts of the printer.This card is normally separate inthe higher end DMP modelshowever in some lower end modelsit may also be integrated with thelogic card.

4) Front Panel:The front panel of DMP's varies from model to model however most of theprinters will have the following LED's and buttons which have been displayed

LF/FF button• Feeds paper line by

line when pressedand released.

• Ejects a singlesheet or advancescontinuous paper tothe next top-of-formposition when helddown.

Paper Out light• On when no paper is

loaded in the selectedpaper source or paperis not loaded correctly.

• Flashes when paperhas not been fullyejected or a paper jamhas occurred.

Tear Off lights**• When continuous paper is in

the tear-off position, otherwise thelamps indicate the selected font.

Tear Off button**• Advances continuous paper to

the tear-off position.• Feeds continuous paper

backward from the tear-offposition to the top-of-formposition.

Load/Eject button• Loads a single sheet of

paper.• Ejects a single sheet of

paper if a sheet is loaded.• Loads continuous paper

from the stand-by position.• Feeds continuous paper

backwards to the stand-byposition.

Pause buttonStops printing temporarily, andresumes printing when pressedagain. When pressed for threeseconds, turns on the microadjust mode. *To turn off, pressagain.

Pause light• On when the printer is

paused.• Flashes when the printer is

in the micro adjust mode.*• Flashes when the print head

has overheated.

Tear Off

DraftDraft CondencedRomanRoman CondencedSans SerifSans Serif Condenced

Tear Off LF / FF Load / Eject Paper Out

Pause

Font Micro Adjust 3Sec

*Micro Adjust modeWhen you hold down the Pause button for three seconds, the printer enters the micro adjust mode. In this mode,you can press the LF/FF and Load/Eject buttons to adjust the top-of-form or tear-off position.

**Font selectIn Micro Adjust mode, you can select the font to use for printing by pressing the Tear Off button. The Tear Offlights turn on, off or flash to indicate the selected font.

Fig. 21.10 Front PanelButtons and Lights



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along with their functions as shown in fig. 21.10.

ADVANTAGESThese printers are quick in low mode.They are versatile because they can print both graphics and text.They are inexpensive.

DISADVANTAGESThey are noisy for an office setup.In high resolution or NLQ mode they become very slow.

3. LINE PRINTERSThese printers are often used for printing large database reports. Line printer'sspeed is tremendous e.g 1500 lines/minute. They achieve this speed byprinting one line at a time rather than one character at a time. Differenttechnologies exist for line printers.

Some low-end line printers contain print head for each character position ona line and a whole line is printed at a time. Some printers have wheel percharacter position and work on principle of daisy-wheel printers. Only, insteadof hammering the print head spoke, the hammer presses the paper againstthe print ribbon and wheel. Some printers use band or chain technology. Aband or chain of characters runs across the full width of paper and is rotatedalong the length of line. The print hammers that is behind the paper hits thepaper, ribbon and the correct character as it spins past the paper. (There arehammer per printable character position).

ADVANTAGESExtremely high speed hence useful for off-set printing.

DISADVANTAGESVery costly and generally requires special environment for consistent output.

NON-IMPACT TYPE1. INK-JET PRINTERSThese type of printers have similar operation to that ofDMP’s. Only, instead of using ribbons, these printers use“INK CARTRIDGES” which are modules that store areservoir of ink.Inkjet printers work by directing tiny droplets of ink ontopaper. Inkjet printer "heads" don't physically touch thepaper at all. Instead, these printers force ink throughnozzles and spray the ink right onto the paper.The print head contains a series of NOZZLES and are

Fig. 21.11 HP Desk Jet Printer



278

arranged in vertical lines. These nozzles produce fine drops of ink and forma character. The resolution (print quality) depends upon the number of nozzles.(eg., 300 DPI).

Depending on the printer and its technology, there can be between 21 and128 nozzles for each of the four colors (cyan, yellow, magenta, and black).By mixing the colors, the printer can produce almost any color.

There are two types of inkjet printer: thermal and piezo. These are two differenttechnologies used to force the ink from the cartridge and through the nozzle.

Thermal InkjetsThermal inkjets is the older of the two technologies.

It is used by manufacturers, such as Canon and Hewlett Packard, and thismethod is commonly referred to as bubble jet.

They heat the ink in the cartridge (to about 400 degrees Fahrenheit), causingvapour bubbles in the cartridge that rise to the top and force the ink out throughthe nozzle. The vacuum caused by the expelled ink draws more ink down intothe nozzles, making a constant stream.

A typical bubble jet print head has 300 or 600 tiny nozzles, and all of themcan fire a droplet simultaneously.

Piezo PrintingPiezo printing uses an electric charge instead of heat. It is patented by EpsonIt charges piezoelectric crystals in the nozzles, which change their shape as aresult of the electric current, forcing the ink out through the nozzles.

A crystal is located at the back of the ink reservoir of each nozzle. The crystalreceives a tiny electric charge that causes it to vibrate. When the crystal vibratesinward, it forces a tiny amount of ink out of the nozzle. When it vibrates out,

it pulls some more ink into the reservoir to replace the inksprayed out.

The output of both technologies is essentially the same. Theprimary difference between the two is that, with the thermalinkjets. (Hewlett-Packard), every time you replace the inkcartridge, you replace the print head. Traditionally with piezotechnology, only the ink cartridge is replaced and the printhead is a permanent part of the printer.

ADVANTAGESThese are comparatively quiet printers.

DISADVANTAGESOperating cost is very high.


Fig. 21.12 Ink CartridgeCarrier


279

Ink cartridges cost more and do not last long.Ink may require more time to dry and therefore theimage may get blurred.

Parts of Inkjet PrinterParts of a typical inkjet printer include:

Print head assembly

• Print head - The core of an inkjet printer, the printhead contains a series of nozzles that are used tospray drops of ink.

• Ink cartridges - Depending on the manufacturer andmodel of the printer, ink cartridges come in variouscombinations, such as separate black and colorcartridges, color and black in a single cartridge oreven a cartridge for each ink color. The cartridges ofsome inkjet printers include the print head itself.

• Print head stepper motor - A stepper motor moves theprint head assembly (print head and ink cartridges)back and forth across the paper. Some printers haveanother stepper motor to park the print head assemblywhen the printer is not in use. Parking means that theprint head assembly is restricted from accidentallymoving, like a parking brake on a car. (Refer fig.21.13).

• Belt - A belt is used to attach the print head assemblyto the stepper motor.

• Stabilizer bar - The print head assembly uses astabilizer bar to ensure that movement is precise andcontrolled. (Refer fig. 21.14).

Paper feed assembly

• Paper tray/feeder - Most inkjet printers have a traythat you load the paper into. Some printers dispensewith the standard tray for a feeder instead. The feedertypically snaps open at an angle on the back of theprinter, allowing you to place paper in it. Feedersgenerally do not hold as much paper as a traditionalpaper tray.

• Rollers - A set of rollers pull the paper in from thetray or feeder and advance the paper when the print

Fig. 21.13 Print HeadStepper Motor



Fig. 21.14 Stabilizer Barand Belt

Fig. 21.15 Paper FeedRollers



280

head assembly is ready for another pass. (Refer fig.21.15).

• Paper feed stepper motor - This stepper motorpowers the rollers to move the paper in the exactincrement needed to ensure a continuous image isprinted.

Power supplyWhile earlier printers often had an external transformer,most printers sold today use a standard power supplythat is incorporated into the printer itself.

Control circuitryA small but sophisticated amount of circuitry is built into the printer to controlall the mechanical aspects of operation, as well as decode the informationsent to the printer from the computer.Interface port(s)The parallel port is still used by many printers, but most newer printers usethe USB port. A few printers connect using a serial port or small computersystem interface (SCSI) port.

Working of Inkjet Printer:When you click on a button to print, there is a sequence of events that takeplace in the Inkjet Printer.

• The software application you are using sends the data to be printed to theprinter driver.

• The driver translates the data into a format that the printer can understandand checks to see that the printer is online and available to print.

• The data is sent by the driver from the computer to the printer via theconnection interface (parallel, USB, etc.).

• The printer receives the data from the computer. It stores a certain amountof data in a buffer. The buffer can range from 512 KB random accessmemory (RAM) to 16 MB RAM, depending on the model. Buffers are usefulbecause they allow the computer to finish with the printing process quickly,instead of having to wait for the actual page to print. A large buffer canhold a complex document or several basic documents.

• If the printer has been idle for a period of time, it will normally go througha short clean cycle to make sure that the print head(s) are clean. Once theclean cycle is complete, the printer is ready to begin printing.

• The control circuitry activates the paper feed stepper motor. This engagesthe rollers, which feed a sheet of paper from the paper tray/feeder into the


Fig. 21.16 Circuit Boardwith Memory and Processor


281

printer. A small trigger mechanism in the tray/feeder is depressed whenthere is paper in the tray or feeder. If the trigger is not depressed, the printerlights up the "Out of Paper" LED and sends an alert to the computer.

• Once the paper is fed into the printer and positioned at the start of thepage, the print head stepper motor uses the belt to move the print headassembly across the page. The motor pauses for the merest fraction of asecond each time that the print head sprays dots of ink on the page andthen moves a tiny bit before stopping again. This stepping happens so fastthat it seems like a continuous motion.

• Multiple dots are made at each stop. It sprays the CMYK colors in preciseamounts to make any other color imaginable.

• At the end of each complete pass, the paper feed stepper motor advancesthe paper a fraction of an inch. Depending on the inkjet model, the printhead is reset to the beginning side of the page, or, in most cases, simplyreverses direction and begins to move back across the page as it prints.

• This process continues until the page is printed. The time it takes to printa page can vary widely from printer to printer. It will also vary based onthe complexity of the page and size of any images on the page. Forexample, a printer may be able to print 16 pages per minute (PPM) of blacktext but take a couple of minutes to print one, full-color, page-sized image.

• Once the printing is complete, the print head is parked. The paper feedstepper motor spins the rollers to finish pushing the completed page intothe output tray. Most printers today use inks that are very fast-drying, sothat you can immediately pick up the sheet without smudging it.

Laser PrinterLaser printers have become increasingly popular where high print quality isrequired. This is largely due to decreasing cost, which has now reached the

level of a good quality dot-matrix or inkjet printer. (Referfig. 21.17).

The principle of operation is exactly similar to normalphotocopying machine. The basic approach is to firstform an image of the page that is to be printed on aphotosensitive drum in the machine. Powdered ink, ortoner, is then applied to the image on the drum. Nextthe image is electrostatically transferred from the drumto a sheet of paper. Finally the inked image on the paperis fused with heat. A rotating mirror sweeps a laser beamacross the photosensitive drum as it rotates. The laserbeam is turned on and off as it is swept back and forthFig. 21.17 Laser Printer



282

across the drum to produce an image in about the same way that an imageis produced on a raster scan CRT. After the image on the drum is inked andtransferred to the paper the drum is cleaned and is ready for the next page.

One major advantage of laser printers is their high print quality. Commonlyavailable lower priced units have a resolution of 1200 dots per inch. Printspeeds are in the range of 17-19 pages per minute for text and 6 to 7 pagesper minute for graphics.

Lasers are more complex than other types of printers, and consequently muchmore expensive to build. Most manufacturers do not make their own mechanismsor print engines, but use a standard one made by Canon, Ricoh, or Hitachi.This is why so many laser printers from different manufacturers look the same.Mechanically, they are the same. Only the firmware (operating programs inROM) differs.

There are basically two types of print engines: write-white and write-black. Ina write-white engine, the laser writes a negative image to the drum, and toneris attracted to the areas untouched by it. In the write-black engine, toner isapplied to the image produced by the laser. The Canon engine used in theHewlett-Packard Laser Jet Printers, as well as those by Brother, Star and others,is a write-white engine.

Parts of PrinterIn order to reduce maintenance costs, many of the laser printer parts, includingthose that suffer the most wear and tear, have been incorporated into the tonercartridge.

Although this makes replacement of individual parts nearly impossible, itgreatly reduces the need for replacement; those parts that are most likely tobreak are replaced every time you replace the toner cartridge. Unlike ink-jetprinters, the relatively higher cost of laser printers makes their repair a commonand popular option.

The Photosensitive DrumThe photosensitive drum is an aluminium cylinder coated with particles ofphotosensitive compounds. The drum itself is grounded to the power supply,but the coating is not. When light hits these particles, whatever electrical chargethey may have had drains out through the grounded cylinder. The drum, usuallycontained in the toner cartridge can be wiped clean if it becomes dirty. If thedrum becomes scratched, the scratch will appear on every page printed fromthat point on. The only repair in the event of a scratch is to replace the tonercartridge.


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Erase LampThe erase lamp exposes the entire surface of thephotosensitive drum to light, making the photosensitivecoating conductive. Any electrical charge present in theparticles bleeds away into the ground drum, leaving thesurface particles electrically neutral.

Primary CoronaThe primary corona wire, located close to thephotosensitive drum, never touches the drum. Whencharged with an extremely high voltage, an electric field

(or corona) forms, enabling voltage to pass to the drum and charge thephotosensitive particles on its surface. The primary grid regulates the transferof voltage, ensuring that the surface of the drum receives a uniform negativevoltage of between ~600 and ~1,000 volts.

LaserThe laser acts as the writing mechanism of the printer. Any particle on the drumstruck by the laser becomes conductive, enabling its charge to be drained awayinto the grounded core of the drum. The entire surface of the drum has auniform negative charge of between ~600 and ~1,000 volts following itscharging by the primary corona wire. When particles are struck by the laser,one can "write" an image onto the drum. Note that the laser writes a positiveimage to the drum.

TonerThe toner in a laser printer is a fine powder make up of plastic particles bondedto iron particles. The toner cylinder charges the toner with a negative chargeof between ~200 and ~500 volts. Because that charge falls between theoriginal uniform negative charge of the photosensitive drum (~600 to ~1,000volts) and the charge of the particles on the drum's surface hit by the laser(~100), particles of toner are attracted to the areas of the photosensitive drumthat have been hit by the laser (that is, areas that have a relatively positivecharge with reference to the toner particles).

Transfer CoronaTo transfer the image from the photosensitive drum to the paper, the papermust be given a charge that will attract the toner particles off of the drum andonto the paper. The transfer corona applies a positive charge to the paper,drawing the negatively charged toner particles to the paper. The paper, withits positive charge, is also attracted to the negatively charged drum. To preventthe paper from wrapping around the drum, a static charge eliminator removesthe charge from the paper.


Fig. 21.18 Laser Printer'stoner cartridge


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FuserThe toner is merely resting on to of the paper after the staticcharge eliminator has removed the paper's static charge.The toner must be permanently attached to the paper tomake the image permanent. Two rollers, a pressure rollerand a heated roller, are used to fuse the toner to the paper.The pressure roller presses against the bottom of the pagewhile the heated roller presses down on the top of thepage, melting the toner into the paper. The heated rollerhas a non-stick coating such as Teflon to prevent the tonerfrom sticking to the heated roller.

WorkingThe printing process takes six steps in this order:1. Clean 4. Develop2. Charge 5. Transfer

3. Write 6. Fuse

Clean the DrumThe printing process begins with the physical and electrical cleaning of thephotosensitive drum. Before printing each new page, the drum must bereturned to a clean, fresh condition. All residual toner left over from printingthe previous page must be removed, usually by scraping the surface of thedrum with a rubber cleaning blade. If residual particles remain on the drum,they will appear as random black spots and streaks on the next page. Thephysical cleaning mechanism either deposits the residual toner in a debriscavity or recycles it by returning it to the toner supply in the toner cartridge.The physical cleaning must be done carefully. Damage to the drum will causea permanent mark to be printed on every page. (Refer fig. 21.19).

The printer must also be electrically cleaned. One or moreerase lamps bombard the surface of the drum with theappropriate wavelengths of light, causing the surface particlesto completely discharge into the grounded drum. After thecleaning process, the drum should be completely free of tonerand have a neutral charge.

Charge the DrumTo make the drum receptive to new images, it must be charged.Using the primary corona wire, a uniform negative charge isapplied to the entire surface of the drum (usually between ~600

and ~1,000 volts). (Refer fig. 21.20).

Fig. 21.19 Cleaning andErasing the Drum



Fig. 21.20 Charging theDrum with a uniformnegative charge


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Write and Develop the ImageA laser is used to write a positive image on the surfaceof the drum. Every particle on the drum hit by the laserwill release most of its negative charge into the drum.Those particles with a lesser negative charge will bepositively charged relative to the toner particles and willattract them, creating a developed image. (Refer fig.21.21).

Transfer the ImageThe printer must transfer the image from the drum ontothe paper. Using the transfer corona, we charge the

paper with a positive charge. Once the paper has a positive charge, thenegatively charged toner particles leap from the drum to the paper. At this point

the particles are merely resting on the paper. They muststill be permanently affixed to the paper. (Refer fig.21.22).

Fuse the ImageThe particles must be fused to the paper. They havebeen attracted to the paper because of the positivecharge given to the paper by the transfer corona, butif the process stopped there, the toner particles wouldfall off the page as soon as the page was lifted. Thetoner particles are mostly composed of plastic, so theycan be melted to the page. Two rollers, a heated rollercoated in a non-stick material and a pressure roller,

melt the toner to the paper, permanently affixing it. Finally, static chargeeliminator removes the paper's positive charge. Once the page is complete,the printer ejects the printed copy and the process begins again with thephysical and electrical cleaning of the printer.

Setting Up PrintersSetting up a printer is easy in Windows. Most printers are Plug and Play, soinstalling a printer is reduced to simply plugging it in and loading the driver.If the system does not detect the printer or if the printer is not PnP, click StartSettings | Printers to open the Printers applet. The icon for this applet can alsobe found in the Control Panel. Fig 21.23 shows a Printer applet with no printersinstalled. Note the only icon: Add Printer.

As you might guess, a new printer is installed by starting the Add Printer applet.This starts the Add Printer Wizard. After a pleasant intro screen, the screenshown in Fig. 21.24 appears.


Fig. 21.21 Writing the Imageand applying the toner


Fig. 21.22 Writing the Imageand applying the toner


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You may choose to install a printer plugged directly into your system or anetwork printer. If you choose a local printer the manufacturer and the modelof printer. It then asks you to select the printer port to which the printer isconnected as shown in Fig. 21.25. Then set a printer name when promptedfor it and then is prompted to print a Windows Test Page and after confirmationprints a Test Page.

How do I install a new printer?

A USB port is a socket on your computer that allows you to plug devices suchas a printer, digital camera, or scanner into your computer. If your printercan be connected to your computer via a USB port, Vista may be able toautomatically install your printer. To add a network, Bluetooth, or wirelessprinter:




4. Click Add a Printer. The Add Printer Wizard appears.

5. Click Add a Network, Wireless, or Bluetooth. The Add Printer Wizard findsall available printers.

6. Select the printer you want to install.

7. Follow the steps outlined by the wizard to complete the installation.How do I cancel a print job?





5. Double-click the printer you are using. The printer's dialog box appears.

6. Click the job you want to stop. If you want to stop more than one job, holddown the Ctrl key while you click the additional jobs.

7. Click Document, which is located on the menu bar. A drop-down menuappears.

8. Click Cancel. You asked if you are sure you want to cancel the print job.

9. Click Yes. Vista cancels the print job.

When you start a print job, a print icon may appear on the taskbar in thenotification area. You can click the icon to open the printer's dialog boxmention in step 5.


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How do I cancel every print job?






6. Click Printer, which is located on the menu bar.

7. Click Cancel All Documents. The document you are printing may finish,but Windows Vista cancels all other documents.

How do I temporarily stop selected jobs from printing?






6. Right-click the document you want to pause. A menu appears.

7. Click Pause Printing. Vista pauses the printing of your document.

How do I restart print jobs I temporarily stopped?




4. Click Printer. The Printers window appears.

5. Double-click the printer you are using. The Printer window appears.

6. Right-click the document that you want to resume printing. A menu appears.

7. Click Resume. The document starts printing again.

TroubleshootingIt's hard to discuss printer problems and troubleshooting without delving toodeeply into the specifies of the thousands of models out there.

As always, try to isolate the problems. Something in the computer or itssoftware. The printer interface? The cable? The printer? Is the printer pluggedin, cabled, and online?

The steps are as follows :1. Check whether the printer is online, is plugged in, has paper, and is turned

on.


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2. Turn the printer off and then on again. Reboot the computer, and try it again.

3. If it is a network printer, check the network configuration (such as the IPaddress and subnet mask on TCP/IP).

4. Use the printer self-test to see whether the test page prints correctly. Theprinter's manual usually tells how to do this.

5. Check that the software is configured for the printer and that the correctdrivers are loaded for it in Windows (if used).

6. Swap the printer cable to make sure your cable isn't faulty.

7. If it is network printer, try printing from another computer.

8. Swap the printer with a different one of the same model, if possible.

Some other things to check are:

• Do a DIR from the command prompt, and then try a screen print using thePrint Screen key.

• If you are troubleshooting a network printer, check the queue at the serverto be certain there are no stuck jobs. If there are, then purge the queue.

• Check the printer manufacturer's Web site to see whether an updated driveris available for your version of Windows or for the particular DOS-basedprogram you want to print from.

Multi Function Printer

An MFP (Multi Function Product/ Printer/ Peripheral), multifunctional, all-in-one(AIO), or Multifunction Device (MFD), is an office machine which incorporates

the functionality of multiple devices in one, so as to have asmaller footprint in a home or small business setting, or toprovide centralized document management/distribution/production in a large-office setting. A typical MFP may act asa combination of some or all of the following devices:

• Printer

• Scanner

• Photocopier

• Fax

• E-mailAdvantages of multifunction printers:

1. Low cost - it is often cheaper to buy a multifunction printerthan individual components (fax machine, scanner, printer,copier) separately

2. Take up less room



289

LAB EXERCISE 21.1 : Printing with Different Printers

Objective: To be able to identify the different parts of different types of printersas well as print using the appropriate printer drivers.

Tasks:

1. Open up an old Dotmatrix printer (DMP) and identify the different parts ofthe printer such as the print head, the carriage unit, the logic board, thesupply board unit if present, the different motors, ribbon, etc.

2. Observe the different LED display combinations as well as the buttons in thefront panel of the DMP.

3. Open a Deskjet printer and identify the different printer parts such as thecarriage unit, the different motors, the logic board, and the two LED's andtheir functions etc.

4. Identify the purpose of the buttons and perform a self test of the DeskjetPrinter.

5. Test whether the deskjet printer is communicating with the PC by printing thetest page after the installation of the printer driver

6. Identify the different parts in a old laser printer such as the logic board, thefuser, the paper pickup assembly, the interface system as well as socketsavailable for memory expansion etc.

7. Identify the function of each LED and the buttons on the front panel andperform a self test of the laser printer.

8. Now, after the installation of the drivers of the printer, test the communicationbetween the PC and the printer by printing the test page.

Disadvantages of multifunction printers:

1. If one component is broken, the entire machine has to be replaced

2. Failure in any component will affect other functions

3. The print quality and speed may be lower than some stand alonecomponents


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Display Interfaces & Monitor

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CMS COMPUTER INSTITUTECMS COMPUTER

INSTITUTE

22PC ENGINEERING


Video DisplayAs much as the mouse and keyboard, the video display is a vital part of theuser interface of any computer.

The video display is actually a latecomer to computing; before CRT monitorscame into general use, the teletypewriter was the standard computer interface-a large, loud device that printed the input and output characters on a roll ofpaper. The first CRT displays were primitive by today's standards; they displayedonly text in a single color (usually green), but to users at the time they werea great improvement, allowing real-time display of input and output data.

Today, PC video displays are much more sophisticated, but you must be carefulwhen selecting video hardware for your computer. Working with even the fastestand most-powerful PC can be a chore when the video adapter slows the systemdown, causes eyestrain, or is unsuitable for the tasks you want to accomplish.

The video subsystem of a PC consists of two main components:

• Monitor (or video display). The monitor can be either a CRT or an LCDpanel.• Video adapter (also called the video card or graphicsadapter). On many recent low-cost systems, video might bebuilt into the motherboard or included as part of thismotherboard's chipset.

How CRT Display Technology WorksA monitor can use one of several display technologies. Themost popular technology continues to be cathode ray tube(CRT) technology, the same technology used in television sets.CRTs consist of a vacuum tube enclosed in glass. One endof the tube contains an electron gun assembly that projectsthree electron beams, one each for the red, green, and bluephosphors are used to create the colors you see on screen;

the other end contains a screen with a phosphorous coating.

Display Interfaces &Monitor


Fig. 22.1 PC Monitor


292


When heated, the electron gun emits a stream ofhigh-speed electrons that are attracted to the otherend of the tube. Along the way, a focus control anddeflection coil steer the beam to a specific point onthe phosphorous screen. When struck by the beam,the phosphor glows. This light is what you see whenyou watch TV or your computer screen. Three layersof phosphors are used: red, green, and blue.

A metal plate called a shadow mask is used to alignthe electron beams; it has slots or holes that dividethe red, green, and blue phosphors into groups ofthree (one of each color). Various types of shadowmasks affect picture quality, and the distance betweeneach group of three (the dot pitch) affects picturesharpness.

The phosphor chemical has a quality called persistence, which indicates howlong this glow remains on screen. Persistence is what causes a faint image toremain on your TV screen for a few seconds after you turn the set off. Thescanning frequency of the display specifies how often the image is refreshed.

You should have a good match between persistence and scanning frequencyso the image has less flicker (which occurs when the persistence is too low) andno ghost images (which occurs when the persistence is too high).

Refresh RateVideo data is displayed on the monitor as the electron guns make a seriesof horizontal sweeps across the display, energizing the appropriate areas ofthe phosphorous coating. The sweeps start at the upper-left corner of themonitor and move across and down to the lower right corner. The screen is"painted" only in one direction, then the electron gun turns and retraces its pathacross the screen, to be ready for the next sweep. These sweeps are called rasterlines.

The speed at which the electron beam moves across the screen is known asthe horizontal refresh rate (HRR). The monitor draws a number of lines acrossthe screen, eventually covering the screen with glowing phosphors. The numberof lines is not fixed, unlike television screens, which all have a fixed numbersof lines. After the guns reach the lower-right corner of the screen, they all turnoff and point back to the upper-left corner. The amount of time it takes to drawthe entire screen and get the electron guns back up to the upper-left corneris called the vertical refresh rate (VRR).

Video cards "push" the monitor at a certain VRR and then the monitor produces

Fig. 22.2 Typical CRTMonitor


ShadowmaskGlassPanel

InternalMagneticshield

Red, Green,and Bluephosphors

Electron gunassembly


293


a noticeable flicker, causing eyestrain and headachesfor users. Pushing the monitor at too high of a VRR,however, causes a definite distortion of the screenimage and will damage the circuitry of the monitorand eventually destroy it.

Monitors were limited to a fixed VRR. Around 1986,NEC introduced the first monitor to support automaticselection of multiple VRRs, called a multiple-frequencymonitor. NEC coined the term "MultiSync" to describeits line of multiple-frequency monitors, but techs tendedto call any monitor that handled multiple refreshrates a MultiSync monitor. All monitors used on PCstoday are MultiSync.

Phosphors and Shadow MaskAll CRT monitors contain dots of phosphorous or some other light-sensitivecompound that glows red, green, or blue when an electron gun sweeps overthem. Each dot is called a phosphor. These phosphors are evenly distributedacross the front of the monitor. (Fig. 22.3)

The CRT has three electron guns: one to hit the red phosphors, one for the bluephosphors, and one for the green phosphors. It is important to understand thatthe electron guns do not fire colored light; they simply fire electrons at differentintensities, which then make the phosphors glow. The higher the intensity, thebrighter the color. Which then make the phosphors glow. The higher theintensity, the brighter the color. Directly behind the phosphors is the shadowmask, a screen that enables only the proper electron gun to light the properphosphors. (Fig. 22.3). This prevents for eg., the red electron beam from"bleeding over" and lighting neighboring blue and green dots.

The electron guns sweep across the phosphors as a group, turning rapidly onand off as they move across the screen. When the group reaches the end ofthe screen it moves to the next line. It is crucial to understand that turning theguns on and off, combines with moving the runs to new lines, creates a "mosaic"that is the image you see on the screen. The number of times the guns turnon and off, combined with the number of lines drawn on the screen, determinesthe number of mosaic pieces used to create the image. These individual"pieces" are called pixels, from the term "picture elements". Just the area ofphosphors lit at one instant when the group of guns is turned on. The size ofpixels can change, depending on the number of times the group of guns isturned on and off and the number of lines drawn.

Not all monitors use dots. The popular Sony Trinitron line of CRT monitors uses


Fig. 22.3 A monitor is agrid of red, green, and bluephosphors.


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bars of red, green, and blue instead ofdots. The holes in the shadow maskhave a rectangular shape. Many peoplefeel this makes for a much more crisp,clear monitor. Somebody must agreewith the as the Trinitron enjoystremendous popularity. Even though thephosphors and shadow mask have adifferent shape, everything you learnhere goes for Trinitrons also.

ResolutionMonitor resolution is always shown asthe number of horizontal pixels timesthe number of vertical pixels. A resolution

of 640x480, therefore, indicates a horizontal resolution of 640 pixels and avertical resolution of 480 pixels. If you multiply the values together, you cansee how many pixels are on each screen: 640 x 480=307, 200 pixels perscreen. An eg., of resolution affecting the pixel size is shown in Fig. 22.3. Theseresolutions match a 4:3 ratio. This is called the aspect ratio. Most monitorsare shaped like television screens, with a 4:3 aspect ratio, so most resolutionsare designed to match-or at least be close to-that shape.

A pixel must be made up of at least one red, one green, and one bluephosphors to make any color, so the smallest theroretical pixel would consistof one group of red, green, and blue phosphors, a triad. Various limitationsin screens, controlling electronics, and electron gun technology make themaximum resolution much bigger than one triad.

Each discrete dot of phosphors is called a phosphordot, each triangle of three phosphors (one red, onegreen, one blue) is called a triad, and each groupof dots painted as the electron beam sweeps acrossthe screen is called a pixel. Higher resolutions sweepa narrower beam with more pixels per row, and lowerresolutions sweep a wider beam with fewer pixels perrow.

The horizontal refresh rate (HRR) defines the speed atwhich the monitor can draw one line on the screen,while the vertical refresh rate (VRR) defines how manytimes per second the entire screen is redrawn. Thesevalues relate to the number of vertical resolution


High Resolution

Low Resolution

Fig. 22.4 Resolution andPixel size


Fig. 22.5 One triad


295


lines, as follows:

HRR = (VRR) x (number of lines), so (number of lines) = (HRR) ÷ (VRR)

Given the HRR and VRR, you can determine the maximum number of lines ofresolution a monitor can support. For eg., given an HRR of 31.5 kilohertz (KHz= thousands of cycles/second) and a VRR of 72 Hertz (Hz), what would be themaximum number of lines on the screen? Could you support 640x480? Take31.5 KHz and divide it by 72 Hz: 31,500 ÷ 72 = 437 lines. So now, with anHRR of only 31.5 KHz, you would have to either reduce the resolution or reducethe VRR and put up with increased screen flicker. By reducing the VRR to 60Hz, the formula would be 31,500 ÷ 60 = 525 lines. Because 525 > 480, oneknow that your monitor could support 640 x 480 resolution at that HRR andVRR.

Alternately, you could increase the HRR from 31.5 KHz to a value that enables480 lines at a VRR of 72 Hz. If you used an HRR of 37.9 KHz and divided itby 72, you would have a maximum line value of 526, which would enablea 640 x 480 resolution.

Dot PitchThe resolution of a monitor is defined bythe maximum amount of detail the monitorcan render. The dot pitch of the monitorultimately limits this resolution. The dotpitch defines the diagonal distance betweenphosphorous dots of the same color, andis measured in millimetres. Because a lowerdot pitch means more dots on the screen,it usually produces a sharper, more definedimage. Dot pitch works in tandem with themaximum number of lines the monitor cansupport in order to determine the greatest

working resolution of the monitor. It might be possible to place an image at1,600 x 1,200 on a 15-inch monitor with a dot pitch of .31mm, but it wouldnot be very readable.

The dot pitch can range from as high as .39 mm to as low as .18 mm. Formost Windows-based applications on a 17-inch monitor, most people find that.28 mm is the maximum useable dot pitch that still produces a clear picture.

InterlacingTo keep costs down, some low-end monitors produce interlaced images. Thismeans that the monitor sweeps or refreshes alternate lines of pixels on thedisplay. In other words, it takes two sweeps through the screen to make one


Fig. 22.6 Dot Pitch


296


image. In its first pass, the monitor covers all the odd lines, and on the nextpass it covers the even line. Interlacing enables a low-end monitor to supportfaster refresh rates by giving it twice as much time to make a screen. Butinterlacing depends on the ability of the eye and brain to combine the twoseparate sets of lines into one stable image. Interlacing is another way ofcreating eyestrain and headaches, and should be avoided.

Video Adapter TypesA monitor requires a source of input. The signals that run to your monitor comefrom a video adapter inside or plugged into your computer.

The three ways computer systems connect to either CRT or LCD displays areas follows:

• Add-on video cards. This method requires the use of an AGP or a PCIexpansion slot but provides the highest possible level of performance andthe greatest versatility in memory size and features.

• Video-only chipset on motherboard. Performance is less than with add-onvideo cards, and memory is seldom upgradeable.

• Motherboard chipset with integrated video. Lowest cost of any videosolution, but performance is also very low, especially for 3D gaming orother graphics-intensive applications. Resolution and color-depth optionsare also more limited than those available with add-on video cards.

Most systems that use Baby-AT or ATX motherboards typically use add-on videocards, whereas older LPX, NLX, and Micro-ATX motherboards typically usevideo chipsets on the motherboard. Many of the most recent low-cost computersbuilt on the Micro-ATX, Flex-ATX, or NLX form factors use motherboard chipsetsthat integrate video, such as the Intel 810 series.

Systems with integrated video (either with video chipsets or motherboardchipsets that include video) usually can be upgraded with an add-on videocard, but most do not include an AGP slot, which is best suited for high-speedvideo today.

Display AdaptersAlthough many types of display systems were at one time considered to beindustry standards, few of these are viable standards for today's hardware andsoftware.

MDA VIDEO STANDARD : IBM's Monochrome Display Adapter is capableof displaying a resolution of 720x350. This is a text-only (no graphics)standard.

Hercules Video Standard: Monochrome adapter capable of high resolution(720x348) text and graphics.


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CGA Video Standard : IBM's Colour Graphics Adapter produces text andgraphics in two modes; choose four colors from a palette of 16 with 320x200resolution, or two colors with 640x200 resolution.

EGA Video Standard : IBM's Enhanced Graphics Adapter produces sharptext and graphics in 16 colors from a palette of 64 colors with 640x350resolution.

MCGA Video Standard : IBM's Multi-Color Graphics Array is an adapterbuilt into the PS/2 Model 30. It produces sharp text and graphics in severalmodes and 256 colors from a palette of 256,000 colors with 320x200resolution. Two-color display has 640x480 resolution. MCGA also offers 320-200 resolution with 64 shades of gray.

Video Graphics ArrayPS/2 systems incorporated the primary display adapter circuitry onto themotherboard, and both IBM and third-party companies introduced separateVGA cards to enable other types of systems to enjoy the advantages of VGA.

Although the IBM MicroChannel (MCA) computers, such as the PS/2 Model 50and above, introduced VGA, it's impossible today to find a brand-newreplacement for VGA that fits in the obsolete MCAbus systems. However, surplusand used third-party cards might be available if you look hard enough.

The VGA BIOS (basic input/output system) is the control software residing inthe system ROM for controlling VGA circuits. With the BIOS, software caninitiate commands and functions without having to manipulate the VGAdirectly. Programs become somewhat hardware independent and can call aconsistent set of commands and functions built into the system's ROM-controlsoftware.

Other implementations of the VGA differ in their hardware but respond to thesame BIOS calls and functions. New features are added as a superset of theexisting functions, and VGA remains compatible with the graphics and textBIOS functions built into the PC systems from the beginning. The VGA can runalmost any software that originally was written for the CGA or EGA, unless itwas written to directly access the hardware registers of these cards.

A standard VGA card displays up to 256 colors onscreen, from a palette of262,144 (256KB) colors; when used in the 640x480 graphics or 720x400 textmode, 16 colors at a time can be displayed.

Because the VGA outputs an analog signal, you must have a monitor thataccepts an analog input. VGA displays originally came not only in color, butalso in monochrome VGA models, which use color summing. With colorsumming, 64 gray shades are displayed instead of colors. The summingroutine is initiated if the BIOS detects a monochrome display when the system

Fig. 22.7 VGA Connector

Pin 1



298


boots. This routine uses an algorithm that takes the desired color and rewritesthe formula to involve all three color guns, producing varying intensities ofgray. Users who preferred a monochrome display, therefore, could executecolor-based applications.

Pin Configuration of VGA Connector1 Red out 6 Red return (ground) 11 Monitor ID 0 in

2 Green out 7 Green return (ground) 12 Monitor ID 1 in or data from display3 Blue out 8 Blue return (ground) 13 Horizontal Sync out

4 Unused 9 14 Vertical Sync5 Ground 10 Sync return (ground) 15 Monitor ID 3 in or data clock

Super VGA

When IBM's XGA and 8514/A video cards were introduced, competing

manufacturers chose not to attempt to clone these incremental improvements

on their VGA products. Instead, they began producing lower-cost adapters that

offered even higher resolutions. These video cards fall into a category loosely

known as Super VGA (SVGA).

SVGA provides capabilities that surpass those offered by the

VGA adapter. Unlike the display adapters discussed so far,

SVGA refers not to an adapter that meets a particular

specification, but to a group of adapters that have different

capabilities.

For example, one card might offer several resolutions (such as 800x600 and

1,024x768) that are greater than those achieved with a regular VGA, whereas

another card might offer the same or even greater resolutions but also provide

more color choices at each resolution. These cards have different capabilities;

nonetheless, both are classified as SVGA.

On the VGA cable connector that plugs into your video adapter, pin 9 is often

pinless. Pin 5 is used only for testing purposes, and pin 15 is rarely used; these

are often pinless as well. To identify the type of monitor connected to the system,

some manufacturers use the presence or absence of the monitor ID pins in

various combinations.

Pin Function Direction Pin Function Direction1 Red Video Out 2 Green Video Out3 Blue Video Out 4 Monitor ID 2 In5 TTL Ground - 6 Red Analog Ground -7 Green Analog Ground - 8 Blue Analog Ground -9 Key (Plugged Hole) - 10 Sync Ground -11 Monitor ID 0 In 12 Monitor ID 1 In13 Horizontal Sync Out 14 Vertical Sync Out15 Monitor ID 3 In


Fig. 22.8 SVGA Connector

1 2 3 4 5

6 7 8 9 10

11 12 13 14 15


299


VESA SVGA StandardsThe Video Electronics Standards Association includes members from variouscompanies associated with PC and computer video products. In October1989, VESA, recognizing that programming applications to support the manySVGA cards on the market was virtually impossible, proposed a standard fora uniform programmer's interface for SVGA cards known as the VESA BIOSextension (VBE). VBE support might be provided through a memory-residentdriver (used by older cards) or through additional code added to the VGA BIOSchip itself (the more common solution). The benefit of the VESA BIOS extensionis that a programmer needs to worry about only one routine or driver to support

SVGA. Various cards from various manufacturers are accessible through thecommon VESA interface.

Today, VBE support is a concern primarily for real-mode DOS applications,usually older games, and for non-Microsoft operating systems that need toaccess higher resolutions and color depths. VBE supports resolutions up to1,280x1,024 and color depths up to 24-bit (16.8 million colors), dependingon the mode selected and the memory on the video card. VESA complianceis of virtually no consequence to Windows versions 95 and up. These operatingsystems use custom video drivers for their graphics cards.

LCD DisplaysBorrowing technology from laptop manufacturers, most major monitor makerssell monitors with liquid crystal displays (LCDs). LCDs have low-glare, completelyflat screens and low power requirements (five watts versus nearly 100 watts foran ordinary monitor). The color quality of an active-matrix LCD panel actuallyexceeds that of most CRT displays.

At this point, however, LCD screens usually are more limitedin resolution than typical CRTs and are more expensive; forexample, a 15-inch LCD screen cost more than twice the costof a high-quality 17-inch CRT monitor. However, it is importantto consider that an LCD screen provides a larger viewableimage than a CRT monitor of the same size. Refer fig. 22.9for an example of a typical desktop LCD display panel.

Three basic LCD choices are available today on notebookcomputers: passive-matrix color, activematrix analog color,and the latest-active-matrix digital.

Monochrome LCD displays are obsolete for PCs, althoughthey remain popular for Palm and similar organizer devicesand are sometimes used for industrial display panels. Virtuallyall passive-matrix designs sold today use dual-scanFig. 22.9 LCD Screen



300


technology, with the dimmer single-scan versions again being related to hand-held organizers. The passive-matrix color panels are primarily found in low-cost notebook computer displays or in industrial-use desktop display panelsbecause of their relatively low cost and enhanced durability compared toactive-matrix models. Desktop LCD panels are analog or digital active-matrixunits.

In an LCD, a polarizing filter creates two separate light waves. The polarizingfilter allows light waves that are aligned only with the filter to pass through.After passing through the polarizing filter, the remaining light waves are allaligned in the same direction. By aligning a second polarizing filter at a rightangle to the first, all those waves are blocked. By changing the angle of thesecond polarizing filter, the amount of light allowed to pass can be changed.It is the role of the liquid crystal cell to change the angle of polarization andcontrol the amount of light that passes. In a color LCD, an additional filter hasthree cells for each pixel-one each for displaying red, green, and blue.

The light wave passes through a liquid-crystal cell, with each color segmenthaving its own cell. The liquid crystals are rod-shaped molecules that flow likea liquid. They enable light to pass straight through, but an electrical chargealters their orientations and the orientation of light passing through them.Although monochrome LCDs do not have color filters, they can have multiplecells per pixel for controlling shades of gray.

In a passive-matrix LCD, each cell is controlled by the electrical charges oftwo transistors, determined by the cell's row and column positions on thedisplay. The number of transistors along the screen's horizontal and verticaledges determines the resolution of the screen. For example, a screen with a1024x768 resolution has 1024 transistors on its horizontal edge and 768 onthe vertical, for a total of 2,000. As the cell reacts to the pulsing charge fromits two transistors, it twists the light wave, with stronger charges twisting the lightwave more. Supertwist refers to the orientation of the liquid crystals, comparingon mode to off mode-the greater the twist, the higher the contrast.

Charges in passive-matrix LCDs are pulsed; therefore, the displays lack thebrilliance of active-matrix, which provides a constant charge to each cell. Toincrease the brilliance, virtually all vendors have turned to a technique calleddouble-scan LCD, which splits passive-matrix screens into a top half andbottom half, reducing the time between each pulse. In addition to increasingthe brightness, dual scan designs also increase the response time and thereforethe perceptible speed of the display, making this type more usable for full-motion video or other applications in which the displayed information changesrapidly.


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In an active-matrix LCD, each cell has its own dedicated transistor behind thepanel to charge it and twist the light wave. Thus, a 1024x768 active-matrixdisplay has 786,432 transistors. This provides a brighter image than passive-matrix displays because the cell can maintain a constant, rather than amomentary, charge. However, active-matrix technology uses more energy thanpassive-matrix, leading to shorter battery life on portable systems. With adedicated transistor for every cell, active-matrix displays are more difficult andexpensive to produce, but in return they offer a faster display that can be usedin outdoor as well as indoor conditions and at wider viewing angles than dualscan displays.

Note: Because an LCD display requires a specified number of transistors tosupport each cell, there are no multiple frequency displays of this type. All thepixels on an LCD screen are of a fixed size, although CRT pixels are variable.Thus, LCD displays are designed to be operated at a specific resolution;however, most recent notebook and desktop display panels offer onboardscaling. Before purchasing this type of display, be sure your video adaptersupports the same resolution as the screen and that the resolution is sufficientfor your needs throughout the life of the monitor.

In both active- and passive-matrix LCDs, the second polarizing filter controlshow much light passes through each cell. Cells twist the wavelength of lightto closely match the filter's allowable wavelength.

The more light that passes through the filter at each cell, the brighter the pixel.

Monochrome LCDs used in hand-held organizers and industrial LCD panelsachieve grayscales (up to 64) by varying the brightness of a cell or ditheringcells in an on-and-off pattern. Color LCDs, on the other hand, dither the three-color cells and control their brilliance to achieve different colors on the screen.Double-scan passive-matrix LCDs (also known as DSTN) have recently gainedin popularity because they approach the quality of active-matrix displays butdo not cost much more to produce than other passive-matrix displays. AlthoughDSTN panels offer better on-axis (straight-ahead) viewing quality than straightpassive-matrix panels, their off-axis (viewing at an angle) performance is still

poor when compared to active-matrix (TFT) panels.

Note: An alternative to LCD screens is gas-plasma technology, typically knownfor its black and orange screens in some of the older Toshiba notebookcomputers. Some companies are incorporating full-color gas-plasma technologyfor desktop screens and color high-definition television (HDTV) flat-panelscreens, such as the Philips Flat TV.


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Flat-Panel LCD DisplaysLCD desktop monitors, once seen mainly on the office sets of futuristic TVshows, are now becoming an increasingly reasonable choice for use in today'soffice computing environment.

LCD desktop monitors offer the following benefits over conventional CRT "glasstube" monitors:

• Virtually 100% of LCD size is viewable area, compared to a loss of 1 to1 1/2-inches of viewable area versus the diagonal tube measurement onCRT monitors. Thus, a 15-inch LCD provides a viewable area roughly equalto a typical 17-inch CRT monitor.

• Small front-to-back dimensions free up desk space.

• Removable bases on some models enable the screen to be mounted ona wall or stand

• Direct addressing of display (each pixel in the picture corresponds with atransistor) and always perfect alignment provide a high-precision imagethat lacks CRT's problems with pincushion or barrel distortion or convergenceerrors.

• Low power consumption and less heat buildup make LCD units lessexpensive to operate.

• Because LCD units lack a CRT, no concerns exist about electromagneticemissions.

• A number of LCD panels offer a pivoting feature, enabling the unit to swivel90°, allowing a choice of the traditional landscape horizontal mode forWeb surfing and the portrait vertical mode for word processing and page-layout programs.

• LCD panels weigh substantially less than comparably sized CRTs. Forexample, the ViewSonic VA 550, a 15-inch LCD display, weighs only 10.1lbs., compared to the 35 lbs.-50 lbs. weight of typical 17-inch CRTs.

There are two major proposals for digital LCD display panel standards:

• The Digital Flat Panel (DFP) standard approved by the Video ElectronicStandards Association (VESA) in February 1999. DFP was previously knownas PanelLink.

• The Digital Visual Interface (DVI) standard proposed by the Digital DisplayWorking Group (DDWG) in April 1999. DVI is much more popular withhardware vendors and has become a de facto standard.

Changing a Video DriverOften the manufacturer of a video card will release new drivers sometime afterthe card has been in production. This may be to take advantage of a feature


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in a new operating system (like Windows 98) or to fix a bug that wasn't apparentat the time the card was manufactured.

To install a new video driver, just follow these steps:

1. Select Start > Settings > Control Panel and click the Display icon.

2. Click the Settings tab and then the Advanced button. This opens even moresettings. Click the Adapter tab here.

3. The Adapter page shows the name of the video card and something aboutits features. Click the Change button.

4. The Update Device Driver Wizard will launch and search for updateddrivers.

Use the default settings except where you can be specific about the locationof the new driver. As with other devices, you may have the driver file on floppydisk, CD-ROM, or a network drive; or you may want the Wizard to check theWindows Update site. If you want, you can let the Wizard search all thelocations.

Note: Deselect the floppy disk drive option if you don't have a floppy disk.Likewise, if you want the system to search the CD-ROM drive, make sure thereis actually a CD in the drive. It won't do any harm, but you'll receive errormessages that will slow the process.

Optimizing Video SettingsThe video settings you can make are limited only by the capacity of your videocard and monitor. Also, some settings-such as very high resolutions on smallmonitors-are aesthetically unappealing, not to mention rendering iconspractically invisible.

To modify your video settings you need to open Display Properties. You cando this by clicking the Display icon in the Control Panel. Or you can right-clickon a blank spot on the desktop and select Properties from the pop-up menu.Then click the Settings tab.

Changing ResolutionsDisplays are described in terms of their resolution-the number of dots on thescreen and the number of colors that can be displayed at the same time. Theresolutions you can choose using the slider under Screen Area choices arebased on what you like to look at - limited by the capabilities of your monitorand video card.

Making Advanced ChangesAlso on the Setting page is a button labelled Advanced. Click this button toget to additional pages for video configuration. Different types of video cards


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will have different effects on these pages. You may have other pages inadditional to the ones described below. Consult the documentation for yourvideo card and monitor for information on how these additional pages areto be used.

If you're using a very high resolution, the desktop elements can be very small.Try Large Fonts under Display to see if that works better for you. (Under theDisplay Properties' Effects page, you can also choose to use Large Icons). Thisway you can preserve the higher resolution and have objects on the desktopthat are legible.

The default setting under Compatibility is to be prompted whenever you makenew color settings. While it's true that some programs require a reboot aftercolors and resolution have changed, most do not. If you do not. If you don'thave a problem program and you change color settings without restarting.

Likewise, if you change display settings often, put a checkmark next to Showsetting icon on task bar. This will place a miniature Display icon on the Taskbar.Click the icon and you can change your display on the spot.

MonitorIf you change your monitor, you usually only need to plug it in and startWindows 98. The monitor will be detected and correctly installed. If the monitorisn't correctly detected, you'll have to provide the right information. Click theChange button and then supply the name of the manufacturer and the model.

Also on the monitor page are several options relating to power managementand Plug-and-Play. These are probably set correctly. However, if you havedisplay problems such as a flashing screen after the monitor returns fromSuspend mode, right-click on each option and read the description. Trychecking on unchecking these options to see if your problem is solved. If youdon't have a problem, leave the settings in their default state.

The Performance page lets you adjust graphics acceleration. Again if yourdisplay is working fine, leave the Hardware Acceleration set to Full. If yourmouse pointer disappears frequently, try moving the slider down one notch.

Many color profiles are included with Windows 98 and you can choose oneor many. Click Add and select a profile. Add as many as you like. Highlightone and click Set As Default.

What's the difference between LCD and LED?LCD stands for "liquid crystal display" and technically, both LED and LCD TVsare liquid crystal displays. The basic technology is the same in that bothtelevision types have two layers of polarized glass through which the liquidcrystals both block and pass light. So really, LED TVs are a subset of LCD TVs.


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LED, which stands for "light emitting diodes,"differs from general LCD TVs in that LCDsuse fluorescent lights while LEDs use thoselight emitting diodes. Also, the placementof the lights on an LED TV can differ. Thefluorescent lights in an LCD TV are alwaysbehind the screen. On an LED TV, the lightemitting diodes can be placed eitherbehind the screen or around its edges. Thedifference in lights and in lightingplacement has generally meant that LEDTVs can be thinner than LCDs, althoughthis is starting to change. It has also meantthat LED TVs run with greater energyefficiency and can provide a clearer, better

picture than the general LCD TVs.LED TVs provide a better picture for two basic reasons. First, LED TVs work witha color wheel or distinct RGB-colored lights (red, green, blue) to produce morerealistic and sharper colors. Second, light emitting diodes can be dimmed.The dimming capability on the back lighting in an LED TV allows the pictureto display with a truer black by darkening the lights and blocking more lightfrom passing through the panel. This capability is not present on edge-lit LEDTVs; however, edge-lit LED TVs can display a truer white than the fluorescentLED TVs.Because all these LCD TVs are thin-screen, each has particular angle-viewingand anti-glare issues. The backlit TVs provide better, cleaner angle viewingthan the edge-lit LED TV. However, the backlit LED TV will usually have betterangle viewing than the standard LCD TV. Both LED and LCD TVs have goodreputations for their playback and gaming quality.

Video projectorA video projector is an image projector that receives a video signal andprojects the corresponding image on a projection screen using a lens system.All video projectors use a very bright light to project the image, and mostmodern ones can correct any curves, blurriness, and other inconsistenciesthrough manual settings.

Video projectors are widely used for many applications such as, conferenceroom presentations, classroom training, home theatre and concerts. Projectorsare widely used in many schools and other educational settings,[1] sometimes



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connected to an interactive whiteboard tointeractively teach pupils.

Overview

A video projector, also known as a digitalprojector, may project onto a traditionalreflective projection screen, or it may be builtinto a cabinet with a translucent rear-projectionscreen to form a single unified display device.

Common display resolutions for a portableprojector include SVGA (800×600 pixels), XGA(1024×768 pixels), 720p (1280×720 pixels),

Projected image from a videoprojector in a home cinema. and 1080p (1920×1080 pixels).

The cost of a device is determined not only by its resolution but also by itslight output. A projector with a higher light output (measured in lumens, "lm")is required for a larger screen or for a room with a larger amount of ambientlight.[2] For example, a light output of approximately 1500 to 2500 ANSIlumens is suitable for small screens viewed in rooms with low ambient light;approximately 2500 to 4000 lm is suitable for medium-sized screens withsome ambient light; over 4000 lm is needed for very large screens or for usein rooms with no lighting control such as conference rooms.

A few camcorders have a built-in projector suitable to make a small projection;a few more powerful "pico projectors" are pocket-sized, and many projectorsare portable.

What is an LCD ProjectorLCD is acronym for 'Liquid Crystal Display'. The paradox here is that we areusing the term liquid and crystal together. Well, this is the case of the LCDProjector the heat from the halogen bulb converts the crystal into a liquid.

LCD Projector WorkingThe LCD video projector contains three LCD panels. At the center of theprojector is a halogen bulb, which is surrounded by the panels. The panelsproduce light. As the halogen bulb heats up, the crystals melt and allow morelight to pass through. Hence, the intensity of the halogen bulb brings aboutthe difference in the tones. Higher the temperature of the bulb, lighter the toneand vice a versa.Images travel to the tube present inside the projector from the DVD player orthe satellite box. These images in turn bounce on a screen that is coated withphosphor. Every fragment of light hitting the screen is termed pixel. On hitting



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the screen, the pixel breaks down into its color componentthat is red, blue or green.The heat produced by the halogen bulb is controlled bythe voltage that flows into the LCD video projector.Considering the voltage that flows into the projector, the3 LCD panels can produce more than sixteen millioncolors. This is what enables us to view all the subtle colorsof a sunset.A single panel is for a single color; meaning one panelhandles all the pixels that are created by the red color,

the second for blue and the third for green. The color images travel as threeseparate beams of light and hit the wall. Here the colors fall on each otherto produce the true color.

LCD Projector MountsThe LCD Projectors available these days provide the feature of displaying theimage upside down so that they can be mounted on the ceiling. Although, thisis a common feature, some manufactures have not incorporated this featureas yet.An LCD Projector mount allows you to mount your projector to the ceiling.While purchasing a mount, ensure that the mount can be rotated 360 degreesand also provides the flexibility of mounting to the wall and angled ceilings.Facility to route the cable inside the channel should also be available.

LCD projector lamps (Bulbs)An LCD projector bulb is a key item in the projector itself and can cost anywherebetween $200 and $500. Therefore, it is very important to consider the listedlamp life before purchasing the projector. A listed lamp life of about 2000hours is the benchmark. Some projectors also provide mode choices, forexample, the 'eco-mode', which not only extends the life of the lamp; it alsoreduces the operating cost of the projector. The two most commonly used bulbsare the metal halide and the UHP type because they project a very white light.The range of listed life of these bulbs is 750 to 2000 hours. While the halogenbulbs have a shorter life span and project light with a yellow tinge, xenon lampsare used in the high-end projectors.

LCD Projector ResolutionThe resolution of an LCD projector can be defined in four different categories:

" UXGA (1600 x 1200): provide very high-resolution and are very expensive.They can support a very broad range of computer equipment.



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" SXGA (1280 x 1024): provide high-resolution images. These projectors aretargeted for people with high-end personal computers.

" XGA (1024 x 768): provide relatively low-resolution images when comparedto UXGA and SXGA. However, as they are less expensive, they are morepopular.

" SVGA (800 x 600): is the most popular resolution today because they areavailable at a reasonable cost and display great images. LCD projectorswith SVGA are ideal for personal computer.

The key factor that decides the cost of an LCD projector is the resolution. Ifyou need it for business purposes wherein you have to give presentations ona daily basis, then you can go for the higher end models. However, if you needit only for personal requirements, like catching up old classics over the weekendlike I do, then you can opt for lower resolutions so that it leaves you with enoughmoney to rent the DVD.


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IntroductionFor years DOS and Windows could play only loud, high-pitched beeps andlow-pitched beeps.

We owe today's multimedia sound abilities to game players. They saw theadvantages of hearing realistic explosions, rocket blasts, gun shots, and mood-setting background music long before developers creating business softwarerealized the practical advantages of sound.

Now, you can listen to your PC speak instructions as you follow along on thekeyboards, dictate a letter by talking into your PC, give your PC spokencommands, attach a voice message to a document, and not have to take youreyes off a hard-copy list while your PC sounds out the numbers as you're typingthem into a spreadsheet.

None of the multimedia that enhances business, personal, and family use ofa PC could exist without sound capabilities. Multimedia CD-ROMs bring theirsubject to life in ways not possible in books because you hear the actual soundsof whales, wars, and warblers, of sopranos, space shots, and saxophones. Notthat sound capabilities must always enlighten you on a topic. You should have

fun with your PC, too.

Sound has become so important that it's helped lead to thedevelopment of a chip called a digital signal processor(DSP) that relieves the computer's main CPU of most of theprocessing chores involving sound. Eventually, expect tofind other types of digital signal, such as voice mail, fax,and video managed by a single DSP that simply followsdifferent instructions for the different types of signals. Andnow that the PC has a voice, it's become fluent in manydifferent digital languages.Media are the electronic and mechanical means a computeruses to communicate with you. The monitor and video card

Multimedia

CMS COMPUTER

INSTITUTE

23PC ENGINEERING

Fig. 23.1 Multimedia PC


CMS COMPUTER INSTITUTE Multimedia

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combination provide you with something to see. Speakers and a sound devicesupply the sound. Force-feedback systems-joysticks that fight back and specialcomputer chairs that rock and roll-take advantage of your sense of touch.

The term multi comes into play when any OS like Windows 98 synchronizesthe activities of the various media, given Windows 98's function as a multimediamediator.

PC Audio AdaptersAt first, consumer audio adapters were used only for games. In 1989, CreativeLabs introduced the Game Blaster, which provided FM-synthesized sound toa handful of computer games. The Game Blaster was soon replaced by theSound Blaster. The Sound Blaster included a built-in microphone jack, stereooutput, and a MIDI port for connecting the PC to a synthesizer or otherelectronic musical instrument. Finally, the audio adapter had the potential forusers other than games. The followup Sound Blaster Pro featured improvedsound when compared to the original Sound Blaster.

Ideally, a Sound Blaster Pro-compatible card would be capable of using

the same IRQ, DMA, and I/O port addresses as a Sound Blaster Pro card fromCreative Labs and would be used by an application program in the same wayas an actual Sound Blaster Pro.

Some cards required two separate sets of hardware resources, using oneset of IRQ, DMA, and I/O port addresses for native mode and a second setfor Sound Blaster Pro compatibility. Others worked well within Windows orwithin an MS-DOS session running with Windows in the background butrequired the user to install a DOS-based Terminate and Stay Resident (TSR)driver program to work in MS-DOS itself. As a result, most MS-DOS gamedevelopers had to develop configurations for each of the leading sound cards.

The replacement of MS-DOS by 32-bit Windows versions starting with Windows95 has made life easier for game and other multimedia developers becauseof a Microsoft innovation called DirectX, which was first introduced in Decemberof 1995.

Sound ProcessingThe sound card can handle more than one signal at a time, allowing you torecord sounds in stereo.

The signals go to an analog-to-digital converter (ADC) chip. The chip changesthe continuous analog signal into the 0s and 1s of digital data.

A ROM chip contains the instructions for handling the digital signal. Newerdesigns use an EPROM (erasable, programmable read only memory) chipinstead of ROM. The EPROM chip allows the board to be updated with


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improved instructions as they're developed.

The ADC sends the binary information to a chip called a digital signalprocessor (DSP) that relieves the computer's main CPU of most of the processingchores involving sound. The DSP gets its instructions about what to do with thatdata from the ROM chip. Typically, the DSP compresses the incoming signalso that it takes less storage space.

The DSP sends the compressed data to the PC's main processor, which, in turn,sends the data to a hard drive to be stored.

To play a recorded sound, the CPU fetches the file containing the compressed,digital replication of the sound from a hard drive or CD-ROM and sends thedata to the DSP.

The DSP decompresses the data on the fly, and sends it to a digital-to-audioconverter (DAC) chip, which translates the digital information to a constantlywavering electrical current.

The analog current is amplified, usually by an amplifier built into the PC'sspeakers. Then the stronger current powers an electromagnet that's part of thespeaker, causing the speaker's cone to vibrate, creating sound.While some types of sounds are straight-forward recordings, such as thosecontained in .WAV files. MIDI sound was developed to save disk space bysaving only instructions of how to play music on electronic instruments ratherthan the actual sounds.

The MIDI instructions tell the digital signal processor (DSP) which instrumentsto play and how to play them.

To assemble entirely new sounds, PC software authors needs way to tell a soundcard. "Play an A as it would sound on a piano. One method is to use frequencymodulation (FM) synthesis. It's usually implemented as a Musical InstrumentDigital Interface (MIDI) circuit.

The notion in FM synthesis is to describe an instrument's waveform in termsof the size of the attack, decay, sustain, and release (ADSR) parts of the cycle.These four elements are generally the basis for sound in terms of waveforms.Attack is the speed at which a sound begins. Decay describes how the soundbegins to release. Sustain describes the actual length of the sound. And finally,release describes when the note is "turned off".

Sound cards vary in how they create sounds, how fine a resolution they usefor sound, and what "extras" they carry onboard, such as a pass-through audiocircuit or a CD-ROM interface.

When it comes to sound cards, 16-bit means something else entirely: it refersto sample types.


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A sample is a recording of a sound, such as a musical instrument, for thepurpose of playback. In this context, the sample attempts to reproduce aninstrument's sound in a digital format. Accurately reproducing an instrument'ssound requires many samples that represent its entire scale of sonic capabilities.A typical collection of samples to cover a wide range of musical instrumentsis around 4 to 8MB in size, after compression. An accurate representation ofa piano requires 16 to 24MB of space!

Eight-bit sample are good for simple game sounds or music. However, youreally need a board with the ability to play back and record 16-bit sounds(at a minimum!) to do good multimedia. The Sound Blaster 16 from CreativeLabs was a good 16-bit card. Nowadays there are 32- and 64-bit cards.

Basic Connectors on Audio Adapter (Sound Card):Most audio adapters have the same basic connectors. These 1/8-inch mini-jack connectors provide the means of passing sound signals from the adapterto speakers, headphones, and stereo systems, and of receiving sound from amicrophone, CD player, tape player, or stereo. The four types of connectorsyour audio adapter should have at a minimum are shown are as shown infig. 23.2.

Stereo line, or audio, out connector (lime green): The line-out connectoris used to send sound signals from the audio adapter to a device outside thecomputer. You can hook up the cables from the line-out connector to stereospeakers, a headphone set, or your stereo system. If you hook up the PC to

your stereo system, you can have amplifiedsound.

Stereo line, or audio, in connector(light blue): With the line-in connector, youcan record or mix sound signals from anexternal source, such as a stereo system orVCR, to the computer's hard disk.

Rear out or speaker/headphoneconnector (no standard color): Oldersound cards often provided an amplifiedjack supplying up to four watts of power foruse with unpowered speakers or headphonesalong with the line-out connector. Today, youare more likely to find this jack being usedfor rear speakers in four-speaker setups. Therear out jack often is disabled by default;

Fig. 23.2 Basic Input and Output Connectors with mostAudio Adapters


Line inMicrophoneLine outRear line outGame MIDI port

Microphone

Front speakers

Joystick

Audio adapter

Rear speakers

Stereo system


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check your audio adapter properties or setup program to see whether you needto enable this port when you connect rear speakers.

Microphone, or mono, in connector (pink): The mono-in connector isused to connect a microphone for recording your voice or other sounds to disk.This microphone jack records in mono, not in stereo, and is therefore notsuitable for high-quality music recordings.

Joystick connector (gold): The joystick connector is a 15-pin, D-shapedconnector that can connect to any standard joystick or game controller.Sometimes the joystick port can accommodate two joysticks if you purchasean optional Y-adapter. Many computers already contain a joystick port as partof a multifunction I/O circuit on the motherboard or an expansion card. If thisis the case, you must note which port your operating system or application isconfigured to use when connecting the game controller.

MIDI connector (gold): Audio adapters typically use the same joystick portas their MIDI connector. Two of the pins in the connector are designed to carrysignals to and from a MIDI device, such as an electronic keyboard. In mostcases, you must purchase a separate MIDI connector from the audio adaptermanufacturer that plugs into the joystick port and contains the two round, 5-pin DIN connectors used by MIDI devices, plus a connector for a joystick.Because their signals use separate pins, you can connect the joystick and aMIDI device at the same time. You need this connector only if you plan toconnect your PC to external MIDI devices.

Many of the newest sound cards are designed for advanced gaming, DVDaudio playback, and sound production uses and have additional connectorsto support these uses, such as

MIDI in and MIDI out: Some advanced sound cards don't require you toconvert the game port (joystick port) to MIDI interfacing by offering these portson a separate external connector. This permits you to use a joystick and havean external MIDI device connected at the same time.

SPDIF (also called SP/DIF) in and SPDIF out: The Sony/Philips DigitalInterface receives digital audio signals directly from compatible deviceswithout converting them to analog format first. SPDIF interfaces are alsoreferred to by some vendors as "Dolby Digital" interfaces.

CD SPDIF: Connects compatible CD-ROM drives with SPDIF interfacing tothe digital input of the sound card.

Aux in: Provides input for other sound sources, such as a TV tuner card.

Pass through and CD ROM InterfacesMany sound cards have a small Berg connector on them designed for a cable,like the one in Fig. 23.3.


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This is an audio pass-through cable. It lets you playmusic CDs from your PC's CD-ROM, through thespeakers on your sound card. This used to be aproblem because getting this audio cable requiredcomplying with each manufacturer's proprietaryrequirements. CD-ROM drives coupled withstandardized cabling for digital audio/video makeit easier to install such devices.

Data CompressionVirtually all audio adapters on the market today can easily produce CD-qualityaudio, which is sampled at 44.1KHz. At this rate, recorded files (even of yourown voice) can consume more than 10MB for every minute of recording. Tocounter this demand for disk space, many audio adapters include their owndata-compression capability.Most manufacturers of audio adapters use an algorithm called AdaptiveDifferential Pulse Code Modulation (ADPCM) compression to reduce file sizeby more than 50%. However, a simple fact of audio technology is that whenyou use such compression, you loose sound quality.When you install an audio adapter, several codecs (programs that performcompression and decompression) are installed. Typically, some form of ADPCMis installed along with many others. To see which codecs are available on yoursystem, open the Windows Control Panel and open the Multimedia icon inWindows 9x. With Windows 9x, click the Devices tab followed by the plus signnext to Audio Compression to see the installed codecs.If you create your own recorded audio for use on another computer, bothcomputers must use the same codec. You can select which codec you want touse for recording sounds with most programs, including the Windows SoundRecorder.The most popular compression standard is the Motion Pictures Experts Group(MPEG) standard, which works with both audio and video compression andis gaining support in the non-PC world from products such as the new cropof DVD players now hitting the market. MPEG by itself provides a potentialcompression ratio of 30:1, and largely because of this, full-motion-videoMPEG DVD and CD-ROM titles are now available. The popular MP3 soundcompression scheme is an MPEG format, and it can be played back on thelatest versions of the Windows 9x Media Player, as well as by MP3- only playerprograms and devices.

MP3 AudioThe hottest thing going in the PC world-soundwise, that is-is a relatively new


Fig. 23.3 Berg Connectorto Connect CD ROM toSound Card


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audio format called MP3. As with most things computer-related, MP3 is anacronym of sorts, standing for MPEG Layer-3. This format deals specificallywith compressing high-quality sound while retaining as much of the originalquality as possible. It does this by removing those ranges of sounds that wecannot hear, which are produced in audio. There is a always a measure of"waste" sound included in all recordings. Now, as more compression is applied,the complex algorithms used to determine what sounds a human is able tohear based on psychoacoustic models trim more and more inside of thehuman hearable range. So, the greater the compression, the lower the quality.

Two factors make up the quality of MP3 files: kHz and Kbps (kilohertz andkilobits per second, respectively). The kHz is in direct relation to the bit depthof the sample. A 16-bit recording is on par with a 44.1kHz recording, alsoknown as White Book or CD-quality audio. Making it 22kHz reduces itsreproduction quality by only one-third. Kbps are the other piece to this two-part puzzle whereas kHz can be correlated to the sharpness of a picture. Kbpscan be correlated to how smooth the sound plays back; Kbps are often referredto as frames.

In cartoons the more "frames" there are, the smoother the apparent motion.Simply put, 60 pictures showing the stages of a person moving their arm overa period of five seconds with result in a more natural movement than will 15frames. Sound works the same way and, again, is represented in Kbps.144Kbps at 44kHz makes for an MPEG Layer-3 file that sounds as good asdigital CD audio but takes up only a fraction of the space. Considering this,Layer-3 can compress a CD-quality audio file to fit about a minute's worth ofsound into roughly a megabyte of space. Your typical three-to five-minute songwould end up being anywhere from 3 to 6MB in size.

Sound DriversA software driver provides a vital link between an audio adapter and theapplication or operating system that uses it. Operating systems such asWindows 9x, XP etc. include a large library of drivers for most of the audioadapters on the market. In most cases, these drivers are written by themanufacturer of the audio adapter and only distributed by Microsoft. Youmight find that the drivers that ship with the adapter are more recent than thoseincluded with the operating system. As always, the best place to find the mostrecent drivers for a piece of hardware is the manufacturer's own Web site orother online services.

Configuring Sound Card in Windows 98Plug and Play (PnP) in Windows 98 has made non-PnP sound cards completelyobselete. Device driver installation in Windows 98 has been reduced to


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inserting a floppy or CD-ROMwith the proper INF file.However, if the sound card isnot configured properly i.e.the driver for the device is notprovided then the sound cardcan be configured with the

proper driver either by running the "Setup.exe" file from the driver CD providedalong with the sound card which will present the screen as shown in the fig.

23.4 or by re-detecting the sound card from the DeviceManager and then giving the drivers for the device or bygoing to the Add/Remove Hardware icon in Control Paneland then installing the sound drivers for the device.

The sound card properly configured would present a volumecontrol icon on the system tray of the taskbar.

The sounds applet in the Control Panel is used to test thespeakers by playing some test sounds, as shown in fig.23.5.

AGP WorkingAGP improves the process of storing texture maps byallowing the operating system to designate RAM for use bythe graphics card on the fly. This type of memory is calledAGP memory or non-local video memory. The net result isthat the graphics controller is required to keep fewer texturemaps in local memory. Thus, using the much more abundant

and faster RAM used by the operating system to store texture maps reducesthe number of maps that have to be stored on the graphics card's memory.

In addition, the size of the texture map yourcomputer is capable of processing is no longerlimited to the amount of RAM on the graphics card.(Refer fig. 23.6)

The graphics controller needs fast access to localvideo memory for screen refreshes and variouspixel elements. Keeping textures out of the framebuffer allows larger screen resolution, or permitsZ-buffering for a given large screen size. As theneed for more graphics intensive applicationscontinues to scale upward, the amount of texturesstored in system memory will increase. AGP delivers


Fig. 23.4 Sound carddetection Screen


Fig. 23.5 Playing a Sound inthe Sounds applet


Fig. 23.6 AGP Working

Local TextureSurface toBackbuffer

PCI

Frame BufferTexture 2

Display GraphicChip

CPU

Chipset

DiskDrive

SystemRAM

to Local

SystemMemory

Texture 1

Texture 2


317

Multimedia

these textures from system memory to the graphics controller at speedssufficient to make system memory usable as a secondary texture store.

The other way AGP saves RAM is by only storing texture maps once. It doesthis with a little trickery. This trickery takes the form of a chipset called theGraphics Address Remapping Table (GART). GART takes the portion of thesystem memory that the AGP borrows to store texture maps for the graphicscard and re-addresses it. The new address provided by GART makes the CPUthink that the texture map is being stored in the card's framebuffer. GART maybe putting bits and pieces of the map all over the system RAM; but when theCPU needs it, as far as it's concerned the texture map is right where it shouldbe.

AGP SpeedsAt its inception the AGP 1.0 standard allowed for both 1X and 2X speeds withthe frequency of X being 66Mhz. AGP 1.0 compliant graphics cards aredesigned to operate at a 3.3Volt AGP signalling. Over the next couple of years,3D applications (games primarily) and graphics cards made to support these3D applications accelerated at a rapid pace. Thus a mere two years after theoriginal AGP standard was ratified, the AGP 2.0 standard was released. AGP2.0 introduced a 4X pipeline and doubled the peak bandwidth of AGP. The1.1GB/sec offered by 4X AGP was sufficient up until now. With the naturalevolution of 3D graphics, today's generation of 3D software and hardwarehave once again begun to challenge the AGP bus. By the fall of 2004 the AGP


AGP 3.3V (1x/2x)Graphics Card

Universal AGP (1x/2x/4x)Graphics Card

AGP 3.0 (1x/2x/4x/8x))Graphics Card (1.5V, 0.8V)

AGP 8X Graphics card on aUniversal 4X/8X slot

Universal AGP Graphics card onAGP 4X slot

AGP 2X Graphics card in a AGP2X slot

Fig. 23.7 Identification ofdifferent AGP Cards andslots


318

3.0 standard was released and with its 2.1 GB/sec. of peak bandwidth (8X)the progression of 3D Graphics is guaranteed to continue.Since the AGP 1.0 operates at 3.3V, they are keyed "AGP 3.3V". They willoperate in AGP 1.0 compliant motherboards as well as AGP 2.0 compliantmotherboards with a "Universal AGP" slot. The latest is the AGP 3.0 which hassignalling voltages of 1.5V, 0.8V. The figs. 23.7 show the different cardsfollowing the different standards and the slots supporting it.

TV Tuner CardsTV Tuner Cards are devices which connect to a computer and feed a signalto the computer so that a television picture (and sound) is shown on thecomputer just like if it was a television. You can connect cable TV to pick upcable channels or a standard TV antenna to pick up local channels.

Terms associated with TV Tuner CardsMPEG: MPEG is a group (Moving Picture Experts Group) that develop standardsfor digital audio and video compression. There are several versions of thisstandard, including MPEG-1, MPEG-2 and MPEG-4.

NTSC: This stands for National Television Standards Committee that developedthe protocol for broadcast transmission and reception in the US. NTSC signalsare used in the US and Japan, and have hardly been altered since theirinception, except for the addition of new parameters for colour signals. NTSCsignals are interlaced, and an NTSC TV image has 525 horizontal lines perframe. Every other line is dropped, and thus it takes two screen scans tocomplete one image. One complete frame is scanned every 1/30 second.NTSC signals are not directly compatible with computer systems, but there areadapters available that let you view an NTSC signal on a PC monitor.

PAL: Phase Alternation Line is the standardthat is used in India and Europe. In the PALstandard, the horizontal image has 625horizontal lines per frame. A slight colorvariation is seen between the PAL and NTSCstandards. This standard was developed inGermany.

SECAM: This stands for Sequential CouleurAvec Memories, and is prevalent in someparts of Europe-mainly in Russia and countriesof the former Soviet Union. Similar to the PALstandard, it is an interlaced transmission signalfor TV.

Cable TVConnector

FM Connector

IR Port

Composite in

Audio In


Audio Out

S-video in

RF Tuner

ADC

Fig. 23.8 TV Tuner Card with Connectors


319

Multimedia

NICAM stereo: This stands for Near Instantaneous Companded AudioMultiplex, and was developed by the BBC Research Centre in the early 1980s.It was first transmitted with the PAL colour broadcasting system in Britain. Thistechnology improves on the sound quality of the transmitted TV signal. TheCompro and Pinnacle TV tuners feature NICAM stereo.

WorkingA TV-tuner card is just another PCI card. Most cards have a very simple layoutwith a RF (Radio Frequency) Tuner unit and an ADC (Analog to DigitalConverter) chip. The ADC chips are mostly manufactured by Brooktree(Conexant) or Philips; and most tuner units are made by Philips. The RF tunerunit is just like the one you have in your TV. The frequency of TV signals liebetween 40MHz and 300Mhz for VHF, and about 800MHz for UHF. FM radiobandwidth is also between 88MHz and 109 MHz, hence the name RF.

The cable wire is plugged into the Tuner unit, where the RF signal is separatedfrom the carrier signal and then passed to the ADC. The converter then samplesthis data, depending on the signal-either NTSC or PAL. The data is then passedon to the video card, where it is overlaid on the frame-buffer.

This saves a lot on the system resources, However, capturing content willdefinitely hog system resources, and affect any other tasks you may be doing.This includes playing games or working with multimedia applications. Workingin Word or Excel, or surfing the Net while capturing content shouldn't be aproblem.

Digital CamerasA good photograph appears to be one smooth, seamless image of widelyvarying color, darkness, and contrast. If you examine it closely enough, youwill see that it chemically consists of the same elements found in electronicphotography. Color film is made up of thin layers of chemicals that react to

three different colors, just as PC displays are made ofthree colors. And chemical film has its own equivalentof a screen's pixels. The film uses the grains of silvercompounds that react to light by clumping together tocreate tiny dots of black and white or different colors.The more and smaller the clumps, the finer the film'sresolution.

A digital image is just a long string of 1s and 0s thatrepresent all the tiny colored dots or pixels-thatcollectively make up the image.

If you want to get a picture into this form, you have twooptions:


Fig. 23.9 Digital Camera


320

• You can take a photograph using a conventional film camera, process thefilm chemically, print it onto photographic paper and then use a digitalscanner to sample the print (record the pattern of light as a series of pixelvalues).

• You can directly sample the original light that bounces off your subject,immediately breaking that light pattern down into a series of pixel values-in other words, you can use a digital camera.

Just like a conventional camera, it has a series of lenses that focus light tocreate an image of a scene. But instead of focusing this light onto a piece offilm, it focuses it onto a semiconductor device that records light electronically.A computer then breaks this electronic information down into digital data. Allthe fun and interesting features of digital cameras come as a direct result ofthis process.

The key difference between a digital camera and a film-based camera is thatthe digital camera has no film. Instead, it has a sensor that converts light intoelectrical charges. (Refer fig. 23.8).

The image sensor employed by most digital cameras is a charge coupleddevice (CCD). Some low-end cameras use complementary metal oxidesemiconductor (CMOS) technology. While CMOS sensors will almost certainlyimprove and become more popular in the future, they probably won't replaceCCD sensors in higher-end digital cameras.

WorkingThe operation of a digital camera is very similar to that of a conventionalcamera in that the image that needs to be captured is focused through a systemof lenses, but the difference lies in the medium that is used for capturing thatimage. In conventional cameras, a light sensitive photographic film is usedand when it is exposed to light the chemicals on the film undergo changes andremain fixed that way. Finally, when the film is developed, the image isobtained.

In a digital camera, the primary sensing element is a Charge Coupled Device(CCD), which is an array of very tiny phototransistors that are arranged in agrid. When this grid is exposed to light, it transmits electricity depending uponthe intensity of the light falling on it. These transistors are the smallest elementson the sensing device and they form the pixels in the image. Therefore, thegreater the number of pixels in the image, the greater will be resolutionsupported and consequentially, the greater is the clarity. In the case of amonochrome digital camera, one pixel would be made up of a singletransistor but in a colour digital camera, each pixel would be composed ofthree separate pixels - red, green and blue. Therefore, together these colours


321

Multimedia

can represent any number of colours depending upon the light incident onthem. This closely mimics the operation of the human eye where rods andcones are used to interpret chrominance and luminance information.

These transistors generate continuous electrical signals that are sent to anAnalog to Digital Converted (ADC) where these signals are converted to adigital format comprising of a stream of 1s and 0s. This bit stream is then sentto a specialised processor called a DSP (Digital Signal Processor) which isprogrammed specifically for handling image information, where variousparameters of the photo like brightness, contrast and image clarity areadjusted. After this, the DSP converts the digital image information into aformat that is compressed, so that it can be stored in the camera's internalmemory or can be transmitted to the host computer.

In many digital cameras available today, the primary storage medium is eithera Flash ROM chip or an internal miniature hard disk drive. Some cameras,especially the high end ones, also feature an interface that can be used forconnecting them to a host computer and exchanging information anddownloading photographs from the camera as the photo is being taken.

In many of the cameras, the viewfinder is in the form of an LCD screen thatdisplays the image that is to be taken. This screen can also be used to previewimages that are already stored on the camera along with other functions likearranging, deleting and transmitting information from the camera to the hostcomputer. Most expensive cameras also feature very impressive functions likeZoom and Panaroma modes where the focal length of the lens can be variedalong with other optical parameters, giving them the flexibility of most of theother conventional cameras.

Web CamerasA simple Webcam consists of a digital camera attached to your computer.

Cameras like these have dropped their prices and they are easy toconnect through a USB port (earlier cameras connected through adedicated card or the parallel port). A piece of software connects tothe camera and grabs a frame from it periodically. For example, thesoftware might grab a still image from the camera once every 30seconds. The software then turns that image into a normal JPG file anduploads it to your Web server. The JPG image can be placed on anyWeb page .

If you don't have a Web server, several companies now offer you a freeplace to upload your images, saving you the trouble of having to setup and maintain a Web server or a hosted Web site. This is the simplestpossible Webcam. Putting a standard JPG image into a standard Web


Fig. 23.10 Web Camera


322

page is straightforward, but it has the disadvantage that your readersmust manually refresh the image. However, it is possible to create asystem that automatically refreshes the image for the readers of the webpage.

JoystickThe functioning of a joystick in its most basic form, is that of a controllerthat tells the computer in what position the handle is placed at any pointin time. Since the handle of a joystick can move in one of two directions,the X-axis (Forward-Backward motion) and the Y-axis (Left-Right motion),the joystick can convey two-dimensional information. However, sometypes of joysticks can also convey information like the rotation of theshaft of the joystick (the R-axis, used for achieving the twisting action in

a game).

The base of the joystick contains a yoke assembly that pivots and thus allowsthe joystick to move freely in the two directions. (Refer fig. 23.12). It is thismotion that is sensed and conveyed to the computer and finally on to thegame. Two sensors are attached to each of the two axes of the joystick yoke,which electrically convey the information of the position of the joystick. Thisinformation is delivered to the game controller card and is finally used by thesoftware to interpret the joystick's position. In the more advanced joysticks,there are more than two axes. Besides the X-Y axis, there may also be additionalcontrols for a special button on the top of the joystick called the POV (PointOf View) hat that enables a player to look around when playing games likeflight simulators.

The buttons on a joystick are simple contact switches that send signals to thecontroller card when they are pressed. Thecontroller card in turn writes a “1” at a specificaddress in memory. This memory address iscontinually scanned and the presence of a highsignal indicates to the software that a button hasbeen pressed. This results in further response inthe game like firing a gun.

Types of sensors: The most important part of thejoystick is the sensor, as this component has to beable to accurately convey the exact position of thejoyst ick. Various methods are used forimplementing this sensor. In the older analogjoysticks, a variable resistor also called a

potentiometer is used ailing with a capacitor. The potentiometer is connectedFig. 23.12 Yoke assembly inJoystick


stick

X-axisshaft

Y-axisshaft

potentiometermotion sensors


Fig. 23.11 Joystick


323

Multimedia

to the two axes of the joystick. Since the capacitor has the ability for storinga charge, depending upon the resistance of the potentiometer - that is thecurrent position of the joystick - the capacitor will take a certain amount oftime to charge and discharge. When the resistance is greater, the time takento charge and discharge will by longer than when the resistance is lesser. Itis this time that is measured in milliseconds by the game controller card andis finally converted to a corresponding digital value that can be further usedby the game in determining the current position of the joystick.

In the newer digital joysticks, accuracy and response time is much greater sincenewer types of sensors are used. In one type of sensor, a special piezo-electriccrystal is used and when pressure is applied to it, the crystal gets distorted andgenerates a certain amount of electric current. Hence, this crystal can be usedas the sensing element.

In another type of sensor, a Light Emitting Diode (LED) is used at one end, witha Charge Coupled Device (CCD) that converts light into electricity at the otherend. Between these two components, there is a strip of film that is graduallyshaded from one end to the other. Therefore, varying degrees of light, unlikeconventional joysticks that are based upon mechanical potentiometers thatcould degrade over time.

Media PlayerThe Media Player is the jack-of-all-multimedia-trades in Windows 98. It canplay CD audio, MIDI, WAV, and AVI files. Media Player can even play DVDVOB (Video Object) files-but it won't let you copy and paste images from DVDto some other application.

LAB EXERCISE 23.1 : Using Multimedia with Media Player

Objective: To be familiar with identification and configuration of the differentmultimedia devices such as the Sound card and adjusting the volume control ofthe Speakers etc.as well as with the different utilities present in Windows 98 suchas Windows Media Player.

Tasks:1. After installing the driver for the Sound card, try using the Windows Media

player.2. Change the volume control settings, and verify whether they are actually

working out or not.3. Also with a Windows Media Player insert a VCD and verify whether it is

able to play all the files present in it.4. In the Windows Media Player try out opening different media files supported

by it.


324

Modem

325


Modems : To communicate between computers over greater distances the

best alternative was to use the present laid down telephone network, which

spans across the whole country. This network can only transmit analog signals,

so normally a device called modem is used to communicate between two

computers.

The term modem combines the words modulator and demodulator. Simply,

the modem modulator circuit converts binary data into tones. At the other end

of the transmission line the demodulator circuit converts the tones back into

binary data. By this technique, a pair of modems can send digital information

over long, distances. The modems allows personal computers to communicate

with mainframes and each other.

Modem permits any two devices to communicate over a single pair of

dedicated wires or the switched telephone network using a serial data

communication protocol. The switched network comprises all the telephone,

any individual can reach any one by dialling a number. The switched telephone

network is not only connected by wires, but it also uses microwave and satellite

transmissions. This means it can not be used to send binary data without first

converting the data to tones, since these are ac-coupled circuits.

The simple modem converts digital

information into two tones. One common

standard converts the RS-232 signals into a

high frequency tone (1270Hz) for a logic 1

and a low-frequency tone (1070 Hz) for a

logic 0. These tones are then transmitted over

a telephone line or any long serial line. Again

the demodulator portion of the modem

converts received tones from the telephone

line back to RS-232 signals.

Modem

CMS COMPUTER

INSTITUTE

24PC ENGINEERING

CARRIERGENERATOR

DIGITALSIGNAL

GENERATORDEMODULATOR

TX

CLK

RX

DTERS 232C

TOPHONE

LINE

SYNC (CLOCK)

MODULATOR


Fig. 24.1 Block diagram of the modem.

326

ModemCMS COMPUTER INSTITUTE

LED Indicators on External ModemThey indicate the condition of the modem and thestatus of its operation. Though the actual locationof these lights may vary from one modem to another,their functionality and naming convention is thesame.

HS: The Highest Speed LED indicates that your modem is currently operating

at its highest rated speed.

AA: The Auto Answer light indicates that your modem will automatically answer

all incoming calls allowing you to access your computer while it's unattended.

CD: Carrier Detect is a signal that the modem sends to the host computer,

informing the computer that it has connected with the remote computer and

has detected a carrier signal, which is the signal used to transmit data using

modulation.

OH: The Off Hook LED lights up whenever the modem takes charge of the

phone line and is the same as the telephone receiver being off the hook.

RD: Receive Data is a signal that lights up whenever

the modem is receiving data from the remote

computer.

TD: Transmit Data is a signal that lights up when the

modem is transmitting data from the host computer

to the remote computer.

TR: The Terminal Ready LED lights up when the

computer sends a DTR (Data Terminal Ready) signal

to the modem, indicating that it is now ready for sending data to the modem.

MR: Modem Ready LED lights up when the modem is turned on and readyfor operation.

Types of ModemsExternal Modems : External modem usually come in small box with seriesof lights in the front and the connection at the back. Installation of the thesetypes is quite easy. To connect it to the computer following cables will berequired

1. Serial cable to connect computer to the modem

2. The phone line

3. A power cable to the modem

COMPUTER

MODEMMODEM

COMPUTER

DIGITAL ANALOG ANALOG DIGITAL


Fig. 24.2 Modemcommunication


COMPUTER

TELEPHONE

PHONE LINESOCKET

TO PHONE

TO LINE

MODEM

Fig. 24.3 Connecting the Mo-dem.

Modem

327


These modems are easy to install, but there are certain disadvantages in usingthem. They require separate power supply and separate serial port as it doesnot have the serial port controller. It is also a bit expensive, but popularly thesemodems are used.

Internal Modems : Internal modems come as a peripheral card which canbe easily fitted into the I/O slot of the PCs. These modems has advantage,as it has its own serial port controller and can be used for high speed datatransfer. Installing them is a bit difficult as the PC has to be opened and therequired port and interrupt jumper setting has to be done before installing it.Internal modems has its own initializing program which can be installed in thememory as a device driver through Config.sys.

Error-Correcting Modems (Present in Internal/External Modem):It has long been possible for communication software to detect errors andrequest retransmission automatically. Error detection and automaticretransmission have now been built into some modems. There are two methodsin common use, which are both described in the V.42 standard issued by CCITT.The first method is called Link Access Procedure for Modems (LAPM). Thesecond method, devised by Microcom, Inc., is called MNP 4. If error detectingis implemented it is necessary that modems on each end of a transmissionagree on which error-correcting method to use. Modems that claim V.42compatibility should support both methods.

Error correction can be important at higher baud rates, where line noise cancause havoc with data communications. However, it is not always necessaryfor the error correction to be built into the modems themselves. Data errorsare most critical when transferring binary files such as programs, where a singleincorrect byte may cause the program not to run. For transferring binary files,the file transfer protocol that itself incorporates error checking and retransmission.In these cases, there is an element of redundancy in using an error-correctingmodem.

Modulation Standards:There are many standards for modulation. These areexplained in brief below: Bell 103 & 212A. These areold standards. Bell 103 transmits at 300 bps at 1 bitper baud. Bell 212A was the next step up, capableof two bits per baud. It was capable of 1200bps at600 baud. Each used a different type of modulation.

V.21. Uses mainly outside the U.S., it was a sort ofinternational standard. It is not compatible with Bellprotocols, and is only capable of 300bps.


Fig. 24.4 External Modem

328


V.22. Shares the features of V.21, but was capableof 1200bps. Later, the V.22bis protocol was used.It was used both in the U.S. and outside, and ranat 4 bits per baud for a total of 2400bps.

V.23. Used mainly in Europe, this allowed themodem to send and receive data at the same time,although it could send data only at 75bps. Thisstandard was developed to lower the cost ofmodems. A 1200 bps modem was very expensiveat the time.

V.29. A half-duplex standard, meaning one-way. Itworks at 9600bps. The standard is not laid out wellfor modems, therefore isn't much used. The protocolis most often used for fax machines.

V.32. This standard began to get users into the ballpark we are all in now.It was a full-duplex standard and operated at 9600bps, with a 2400 baud rate.It incorporates error-correcting and negotiation. The error-correcting allowedV.32 to work well over phone line noise.

V.32bis. This is one step up from v.32. It transmitted 6 bits per baud, allowingthroughputs of 14,400 bps. It also allowed fallback onto regular V.32 if thephone line was impaired. Many still use this modem standard primarily.

V.32fast Better known as the 28,800 bps modem.

V.34. The latest real modem standard. It provides a reliable 28,800 bpsconnection. With upgrades to the ROM BIOS on the modem, the standard isoften used for 33,600 bps transmissions.

V.90. It digitally encodes data and transmits it over phone lines instead ofmodulating it to an analog signal. It provides 56 kbps download rates whileuploading is limited to 33.6 kbps.

BROADBAND TECHNOLOGIESCable Modem:A cable modem is an external device that attaches to your computer. Insteadof getting an Internet connection through your telephone wire, you can get aconnection through your cable network (the same place your cable TV connectioncomes from). Cable modems work by translating radio frequency (RF) signalsto and from the cable plant into internet protocol (IP), the communicationlanguage spoken by all computers connected to the internet. This translationprocess takes place at the cable operator's plant.

When a cable modem is installed, a splitter is placed on the side of the


Fig. 24.5 Internal Modem

Modem

329


customer's home, which separates thecoaxial cable line serving the cablemodem from those serving televisions.A separate coaxial cable line is thenrun from the splitter to the cablemodem, which is located next to thecustomer's computer.

Cable modems typically connect tocomputers through a standard 10Base-T Ethernet interface. A wire (calledCategory 5 cabling) is run from thecable modem to an Ethernet card inthe computer. Data is transmitted

between the cable modem and computer at 10 Mbps.

Features

• Support VPN. (PPTP pass thru) for Internet connection.

• Internet applications such as Web, FTP, Telnet, E-Mail, News, NetMeeting.

• Natural firewall keeps hackers out.

• DHCP server allocates up to 128 client IP addresses.

• DHCP client to get global IP address automatically.

• 4 ports 10/100 base-T Nway Ethernet Switch

• Virtual server.

• Rich packet filters.

• Static routing.

• Support Proxy-DNS.

• Easy setup by Windows GUI program and Telnet through network.

• Flash memory for firmware upgrade.

DSL (Digital Subscriber Line)It is a technology developed by the phone companies in order to competeagainst cable modems. Both technologies came to market at around the sametime, though one or the other may only be available in your area. DSLtechnology works over existing phone lines, and makes use of additionalbandwidth that is not currently used by phones.

The way the technology works has to do closely with how modems work. DSLworks on the basis that a signal travelling over a phone line does not haveto be transferred back and forth between analog and digital realms. DSL


Fig. 24.6 Implementation ofDSL for Home and BusinessPurposes

330


assumes that the data is being sent digitally, and never bothers with theconversion. This allows for greater bandwidth than analog signals could everhope to offer, but allows for the two to coincide on the same line.

Which DSL technology you pick up depends on what your provider is carrying,but xDSL and ADSL seem to be the two most popular variants. ADSL(a =asynchronous) works by focusing much of the bandwidth on the downloadspeed and lowering the upload speed - perfect for most users.

DSL technology requires you to hook up either to a DSL modem, or to a routersystem which is usually provided by your provider (amazing how that works).If you can, opt to go the router route as your connection will be in an 'always-on' state. If you have to get a DSL modem you may be forced to 'dial-in' tothe DSL server each time you reboot or want to connect to the net (which woulddefeat the purpose of having a connection such as this).

ADSL (Asymmetric Digital Subscriber Line)Digital Subscriber Line or DSL is a technology that delivers voice, video anddata at high speeds over conventional telephone lines. ADSL stands forAsymmetric Digital Subscriber Line, a type of DSL service with different(asymmetric) upstream and downstream capabilities. ADSL technology usesyour existing telephone line to your home or office to provide you with a fast,reliable, "Always On" connection to the Internet. You will no longer receive abusy signal or spend time waiting for a connection. In addition, you are ableto use your telephone while surfing the Internet because DSL technology usesdifferent frequencies to transport voice [lower] and data [higher].

ADSL Modem on your end sends data over the telephone line to your service

provider company. At the company; DSL Access Multiprocess redirects voice traffic

to the (PSTN) and data to a high speed digital line that connects to the internet.

The difference between DSL and cable modems

DSL provides always-available high-speed Internet access over a private,

"dedicated" and secure communication channel between you and your service

provider. Cable modems offer high-speed Internet access over a "shared"

cable, where access speed and security are compromised as more users try

to connect.

While cable modems may have greater theoretical downstream (from the

Internet to the home) bandwidth capabilities, that bandwidth is shared among

all users in a neighbourhood, and will therefore vary, perhaps dramatically,

as more users in a neighbourhood get online at the same time.

Broadband is today's reality with demands of connectivity speed exceeding

Modem

331


125 kilobits per second.

Comparing the overall price/performance of both service types, we see that

Cable-modem access has lower installation costs and faster Internet data

download from 3 to 4 megabits per second. According to the supporters of

cable modems, DSL will soon become outdated due to intensive data

requirement of video-on-demand, multi-player games, streaming of audio

and video, Internet software distribution, and other such services that generally

require very high data downloading speeds.

On the other hand, supporters of DSL say that Cable modem access will face

tough time with its inherent security and speed issues - any single addition of

subscriber to a neighbourhood hub dilutes the overall quality of cable-modem

service. On the contrary, DSL is slower than cable with an average speed of

1.5 megabits per second, but is considered far secure and reliable since it's

based on a dedicated line between a home and the phone company. Hence

there is a little security risk of personal computing systems getting hacked when

using DSL access type.

DSL Service Cable Modems Up to 1.5Mbps downstream, 1.5Mbps upstream in a point-to-point connection. Bandwidth is dedicated, not shared, between the user's location and our central office.

Up to 30 Mbps downstream, engineered for sharing between 500-2,000 users. Service deterioration occurs when a large number of users attempt simultaneous transmission. Functionality is very similar to Ethernet LAN technology.

DSL is not subject to eavesdropping in a point-to-point environment. Also, Copper facilities, a staple of DSL technology, is more readily available than alternate (over subscription) technologies such as fiber or cable.

Cable is a shared medium that is subject to eavesdropping, denial of service attacks, service theft and speed degradation.

Bandwidth is easily scalable; An access node can be installed into an area when economically justified to augment DSL coverage.

Subscription can be made only after the entire network is upgraded to Hybrid Fiber/Coax. Simply dropping an optical node will not suffice. The fiber optics and coaxial cable must be in place.

DSL provides for simultaneous voice service on the POTS line.

Current cable modems do not provide for voice and require an analog modem for upstream communications that ties up a dial tone line.

DSL modems only affect a single user if malfunctioning.

A CATV line cut will bring down all users on that line.

332



Fig. 24.8 Install New Modem


Fig. 24.9 Selection of Modemdriver

Configuring a Modem

The following steps below describe the configuration.

Step 1, From the Start button, select Settings and open theControl Panel. Open the Modems tab in Control Panel. Ifyou already have a modem installed in your computer, youwill see modem listed refer fig 24.7, if you do not have amodem installed in your computer Click the Add button.

Step 2, Be sure that your modem is properly connectedand, if it is external, that it is turned on. Do not place a tickin the box titled Don't detect my modem, refer fig 24.8.Click Next to begin the process of detecting your modem.Windows will now attempt to detect your modem byscanning each of the communications ports in your computer

Step 3, Once Windows completes scanning your systemfor your modem, it will list the type of modem that it found.

If the modem listed is not what you have in your computer, click the Changebutton and move to the next step. If your modem is correctly identified, click

the Next button and move to Step 6.

Step 4, Scroll through the list of manufacturers in the lefthand column. If the manufacturer for your modem is listed,click once on that manufacturer. The list of modems willchange in the right hand column. If your modem is listed,click on its entry once then click the Next button. Move toStep 6. If your modem is not listed and you do not havea disk for your modem, click on Standard Modem Typesfrom the left hand column. Then click once on the modemthat most closely matches yours from the list on the right

hand side. Click the Next button. Move to Step 6.

Step 5, If you have a disk for your modem, click the Have Disk button, Insertthe disk that contains your modem software into the diskdrive, Select the correct drive letter and folder that containsthe modem software. You may need to use the browsebutton to change drive letters or folders, Click the OKbutton and move to the next step. Once you have selectedthe correct drive and folder that contains your modemsoftware. The file that Windows is looking for is listed in theFile name box. There will be a file with the same namehighlighted in the list under the file name box, refer fig.

24.9. Click the OK button.


Fig. 24.7 Modem Propertiesdialog box

Modem

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Step 6, Windows will now ask which communications(COM) port you want the modem to communicate through.External modems are usually connected through COM1 orCOM2. Internal modems are usually connected throughCOM3 or COM4. Select the COM port that you want touse (refer fig 24.10) then click the Next button

Step 7, Your modem software has now been installed.Click the Finish button to finalize the settings, Click the OKbutton to close the Modem Properties window.

The Modem Properties dialog box is the next screen to appear (Refer fig 24.7);this figure shows the modem is installed. Here you can manage the modemsinstalled on your comuter. The Add button gives you the option of addinganother modem from a list of available modems; alternatively, the Removebutton enables you to remove a modem from the list of installed modems.

The Properties button of this dialog box displays the General properties dialogbox for the highlighted modem after you choose a modem from the list (seefig. 24.11). This box lists several of the selected modem's properties, such asthe maximum speed and speaker volume. However, the most importantproperty shown here is the Port field: This field tells you the COM port that

modem is configured to.

You can find and define several other modem-specific settings here that have little or no effecton the fax parameters. Settings that may bespecified include speaker volume, the maximumspeed at which the modem may connect,connection preferences (data bits, parity, stop bits),call preferences (wait for dial tone beforeconnecting, cancel if connection is not establishedwithin a given number of seconds, disconnect aftera predefined idle time), whether to use FIFO buffers9 for 16550 UART), error control settings (requiredto connect, compress data, use cellular protocol),flow control settings (hardware (RTS/CTS), software(XON/XOFF), and others. Click on OK to return tothe Modems Properties dialog box and then clickon close to wrap up the property definition process.

Setting Up Internet ConnectionsThis section describes how to connect to the Internet using the Windows 98


Fig. 24.10 Port Selection forModem


Fig. 24.11 Properties for theSelected Modem

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TCP/IP and PPP services. It assumes that you are making a full Dial-UpNetworking connection to an Internet service provider. The following steps aremerely an overview of how you'll connect to the system.

• Install and configure a modem with the Modem utility in the Control Panel.

The next few sections provide more detail about setting up TCP/IP and yourInternet connection.

Configuring a Dial-Up Networking SessionHere are the steps to configure anInternet dial-up connection. These stepsassume the Dial-Up Networking Supportfiles are installed on your computer.

• Open the My Computer window,then double-click the Dial-UpNetworking folder to open it.

• Double-click the Make NewConnection object. The Make NewConnection wizard pictured in Fig.24.12 appears with a list of modemsyou can use on your computer.

• Type a name in the top field thatdescribes what this connection does(for example "Internet dial-upconnection") and then click the Nextbutton.

• In the next wizard box, type the phonenumber that your service providergave you to use when dialing in.

• Click Next, then click Finish tocomplete the operation.

You should now see a new object in the Dial-UpNetworking window for your new Internetconnection, similar to the one shown here:

Dialing Into the InternetTo connect to your service provider, double-clickthe dial-up object you created in the previoussection. You'll see a dialog box similar to the oneshown in fig. 24.13. Type your Internet name in the

User name field. You'll be entering just the first part of your Internet address.


Fig. 24.12 Choosing amodem for the dial-upconnection

Motorola Voice SURFR 56K Internal PnP

My Connection


Fig. 24.13 Preparing to dialout to the internet

Modem

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For example, my Internet address is [email protected] but I'll type only dilipdin this field. Be sure to use lowercase letters.

Click the Connect button to establish the connection. Once you connect withyour service provider, you'll see a small dialog box similar to the following thatindicates the speed of your connection and the amount of time you have beenconnected.

You can click the Disconnect button to end the session, but make sure you firstquit or log out of any session you might have open. Click the Details buttonto see the protocols in use.

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Backup Devices

Tape DriveBacking up your hard disk to a tape drive used to be like one of your mother'swarnings when you were a child: Take an umbrella with you on cloudy daysand always wear a raincoat. Sure, Mom was right once in a while—rain wouldcome down and you would get wet, but it wasn't all that terrible. So what ifyour hard disk's file allocation table got scrambled and you lost half your files.A few years ago, as long as you'd copied a few essential data files to floppies,recreating a couple of megabytes of programs from their original distributiondisks wasn't that much trouble.

Today, however, the implication of a “little” hard-disk disaster have mushroomed.You're more often talking about hard drives that contain not just a few megsof files, but hundreds. A single Windows program may include 30 megabytesof files. And with a complex environment such as Windows, no program existsalone. Many Windows programs you install modify at least one of the .INI filesof Window.

At the same time that it becomes more critical than ever to back up hard drives,disk sizes up to 500 megabytes make the idea of backing up to floppy diskseven more abhorrent. Enter the new breed of less expensive, more capacioustape backup drives. And the ability to copy a gigabyte or more to a singletape makes them simple to use for even the biggest hard drives.

Tapes have been around since 1972 when the first QICs (Quarter InchCartridges) were introduced by 3M to store data from telecommunications anddata acquisition applications. Large-capacity tape-medium still remains thebest option for full-system, network-wide data backups.

Tape drives use magnetic tapes to hold large amounts of data. They can storeup to 72 gigabytes and hence are very useful for very large backups and allowyou to back up your entire system at once. Since they are magnetic all theadvantages of magnetic media along with its disadvantages are applicableto tape drives also.

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Types of DrivesThe drives have been classified on the basis of the methodology adopted torecord data and there are two ways in which this can be done, in a spiral, or'helical' fashion wherein the data tracks are written at an angle with respectto the edge of the tape called the HST (Helical Scan Technology) and the LST(Linear Serpentine Technology) where multiple linear tracks are written parallelto the edge of the tape. In HST, a magnetic tape is partially wrapped aroundan angled, rapidly rotating drum containing the read and write heads. In LST,the tape moves linearly over the head assembly where the precisely alignedread and write heads are located.

The 4mm DAT (Digital Audio Tape), Exabyte's 8mm Mammoth and Sony's AIT(Advanced Intelligent Tape) are based on HST while Quantum's Digital LinearTape (DLT and SuperDLT) and LTO (Linear Tape Open) by IBM, Seagate andHP employ the use of LST.

Tape Drives and their Media:Tape manufacturers usually specify two separate capacities for their tapes:native capacity and compressed capacity. Native capacity is the actualavailable capacity on the media. But, most tape drives use some algorithmto compress data before writing it to tape. This increases the overall availablecapacity.

Tapes and tape drives are rated with two numbers, for eg., "7/14 GB. Herethe first number which is the smaller number represents the storage capacityof the tape and the second which is the larger number is the capacity usingdata compression which doubles the actual capacity of the drive itself.Compression also doubles the data transfer speed.

Digital Linear TapeDigital Linear Tape technology was developed by DEC (Digital EquipmentCorporation) to be used with its MicroVax systems. Quantum acquired thetechnology from DEC in 1994 and has since then been selling various DLTformats.

DLT-drives have a unique HGA (head-guide assembly), which minimizes tapewear. The HGA is a boomerang-shaped aluminium plate with six largebearing-mounted rollers. While in helical scan systems, tape is grabbed fromthe middle and pulled into place, the DLT HGA system links a leader strip onthe end of the tape, pulls the tape out of the cartridge and wraps it aroundthe take-up reel, guided by the rollers.

Quantum introduced the Super-DLT range in 1998, with a much highercapacity (110 GB native in SDLT 220 compared with 40 GB native in DLT8000).The latest SDLT drive from Quantum offers 160 GB native and 320 GB


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compressed capacity, with 16 MB/sec native and 32 MB/sec compressedtransfer rate.

The main advantages of DLT are the higher storage capacity, higher datatransfer rates, and higher reliability because of the HGA which does not allowthe media to touch the head in the drive.

DLT or Digital Linear Tape is supported largely by Quantum but HP, Dell, IBM,Fujifilm, Maxell and Exabyte, also provide DLT products. Like other formats,DLT also has several generations DLT III, DLT IV, DLT VS1. Out of these, DLTIV is the most commonly used. Archival life of DLT media is 30 years and about1,000,000 end to end passes usage life.

DLT IV: capacity 40GB native, 3.0 - 6.0 MB/sec native transfer rate.

All DLT formats are backward compatible

Quarter-inch Cartridge (QIC) Tape Backup DriveWhen you use the software for a quarter-inch cartridge drive to issue a backupcommand, the program reads your hard disk's file allocation table to locatethe files you've told it to back up. The software writes the directory informationto a 32K buffer in your PC's RAM. It then copies the files into the same buffer.Each file is prefaced with header information that identifies the file and itslocation on the hard drive's directory tree.

If the tape drive's controller includes chips that handle error correction, thebackup software dumps the full buffer from RAM to the controller's own buffer,where the chips append error correction (EC) codes. If the controller doesn'thave built-in error correction, the software computes the EC codes based onthe pattern of 0 and 1 bits in the files, appends them to the end of the datain the RAM buffer, and copies the contents of the RAM buffer to the controllerbuffer. Once the data is transferred to the controller, the RAM buffer is free toreceive the next block of data from the disk.

The tape drive's controller sends signals to the tape mechanism to start thetape moving. QIC drives depend on the cartridges to keep the tape taut. Whenthe drive's capstan turns the cartridge's roller, an elastic belt wrapped aroundthe reels of tape stretches slightly as it grips the tape, ensuring that the pullingforce of the take up reel matches the resistance of the supply reel. This makesthe tape press against the drive head with a constant pressure, minimizing writeand read errors.

The controller sends a stream of data to the drive's write head. Many tapedrives have three-part read-while-write head. Two read heads flank a centralwrite head that transfers the data to the magnetic coating on the tape.Depending on which way the tape is moving, one of the read heads reads thedata that's just been written by the write head to verify that the data on the


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tape matches what the write head sent to the next section of disk data. If thedata doesn't check out, the data is rewritten on the next stretch of tape.

Note : To restore a file from tape, the drive uses the directory on the tapeto locate the file, and then reads the file into its buffer. The controller computesa CRC code for each block and compares it with the CRC code written at theend of the block. If there's a discrepancy, error-correction routines usually canfix the data using the EC codes appended to each data block. As the tapedrive's buffer fills up, data is written to the hard disk in the appropriate directory.

The format of a QIC tape typically contains 20 to 32 parallel tracks. When

the tape reaches either end of a spool, its movement reverses and the flow

of data loops back in a spiral fashion to the next outside track. Each track is

divided into blocks of 512 or 1,024 bytes and segments typically contain 32

blocks. Of the blocks in a segment, eight contain error-correction codes. In

addition, at the end of each block, the drive computes a cyclic redundancy

check (CRC) for further error correction and appends it to the block. Most

backup software reserves space for a directory of backed-up file at the

beginning of track 0 or in a separate directory track.

As either end of the tape approaches the drive head, holes punched in the tape

signal the drive to reverse the direction of the tape and to shift the active area

of the recording head up or down to the next track and then continue recording.

When all the data has been written to the tape, the backup software updates

the tape's directory with the track and segment locations of the files that it's

backed up.

Digital Audio-Tape (DAT)

DAT drives are the most popular kind of tape drives. They are available intwo size - 4 mm and 8 mm. These 4 mm size look like small audio cassettes.They were initially designed to store CD like quality of audio.

4mm

DAT (Digital Audio Tape) is used for storing CD-quality audio format. DigitalData Storage or DDS is a DAT-based computer-data storage format, developedby Sony and HP and released in 1989. So what is used with computers is DDS,not DAT, but the name DAT-drives has stuck. DDS has gone through fourdifferent revisions: DDS, DDS-2, DDS-3, DDS-4; the first two formats are notused as much as the others now. HP has further revised this standard and callsthe latest standard DAT 72. DDS cartridges have an archival storage life of10-20 years and a usage life of about 2000 end-to-end passes. DDS cartridgesare quite smaller in size and lightweight compared to other formats.


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DDS-3: capacity 12GB native, 1.2MB/sec native transfer rate

DDS-4: capacity 20GB native, 2.4MB/sec native transfer rate

DAT72: capacity 36GB native, 3MB/sec native transfer rate

DDS format is backward compatible with all previous formats.

8mmThe 8mm tape is similar to DAT but with higher storage capacities. Twoprotocols differentiated by compression algorithms and drive technologiesexist in the 8mm space-the Mammoth by Exabyte and the AIT (AdvancedIntelligent Tape) by Sony and Seagate.

Digital Audio-Tape (DAT) Backup DriveWhen you issue a backup command from your software, the program checksyour hard disk's file allocation table to find the files to back up. Then it copies

the data, file by file, into the digitalaudio tape drive's buffer, whichusually has room for 512K or 1MBof data. Like a QIC tape drive, theDAT drive performs an algorithmon the data to create error-correctioncode that it adds to the data in thebuffer.

The distinctive design of the DAT drive's read/write head is what allows it tobackup huge amounts of data onto a small tape cartridge about the size ofa matchbox. The mechanism is a rotating cylinder with four heads 90 degreesapart. Two of these heads, write heads A and B, write backup data, and twocorresponding read heads verify the data. The cylinder tilts slightly so it rotatesat an angle to the tape. The cylinder spins 2,000 times a minute while the tape(at a rate of 1/2 inch a second) passes in front of the cylinder in the opposite

direction of the cylinder's spin.

During the time that write head A is incontact with the tape, it writes about128K of data and error-correction codesfrom the drive's buffer to a track on thetape. Because the cylinder is tilted, thehead encounters one edge of the tape atthe beginning of the write head and movesdiagonally across the tape until it reachesthe other side. This results in a narrow

diagonal track about eight times longer than the width of the tape.


Fig. 25.1 DAT Backup drive


Fig. 25.2 Mechanism ofrotating cylinder with fourheads


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Read head A readsback and verifies thedata in track A, bit bybit, against the datastill in the buffer. If thedata on the tape ischecked, it's flushedfrom the buffer, and

more data is read from the hard disk. If the data in track A contains errors,the data will be rewritten on the next pass.

As write head B passes over the tape, it writes data in a track at a 40-degreeangle to track A, making a crisscross patternthat overlaps track A. The overlapping datapacks more information per inch of tape; itisn't misread later because the magnetic bitswritten by the two write heads have differentpolarities, and the different read heads readdata only from properly aligned tracks.

Read head B and write head B go through thesame steps, alternating with the A heads until all the data is backed up. Thenthe drive rewinds that tape and writes a directory of stored files either in aspecial partition at the front of the tape or in a file on the hard disk.

Note : When you restore files from the DAT drive, the software reads thedirectory, winds the tape to the spot where the requested files begin, and copiesthe files to the hard disk.

Deciding Factors while selecting a tape drive:Once the business requirement is identified, choosing the right tape technologydepends upon the following factors

i) Tape capacity: The tape manufacturers, specify the native capacity and thecompressed capacity. The actual compression depends on the kind of databeing stored and will therefore not always be equal to the manufacturers'rating. For example, .bmp and text files are more compressible than binaryor .exe files. So, while choosing a backup solution, look for the uncompressed(the native) capacity.

ii) Speed of writing data on tape: This becomes important when you havelots of data to back up, and would like to have it backed up in the shortesttime possible. The capacity and speed would depend upon the tapetechnology you choose. The speeds range from 1.2 MB/sec to 30 MB/sec.

iii) Drive maintenance and service: All tape cartridges have a usable life and


Write head ARead head A

Fig. 25.3 Write Head Awriting Data while ReadHead A verifies it


Fig. 25.4 Write Head Bwriting Data on Tape


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a shelf life, depending upon whether you're using it for backup or archival.So you'll need to see how soon would you have to replace the cartridgesof the technology you choose and what the replacement cost will be.

iv) Interface and form factor: While SCSI is the favorable choice for connectingtape drives, IDE and USB tape devices are also available. SCSI, with somany standards may also crop up installation or performance issues. Apartfrom the interface, things like the size of the tape and drive, whether it'sinternal or external, should be considered.

v) Cost: Last but not the least is the cost at which you get the entire solution.This includes both the price of the drive and the cartridges. The latter isimportant as it's the running cost. It would vary because the number ofcartridges you'll use will vary depending upon your back up strategy.

Zip DriveAfter floppy drives, Zip drives were a miracle in the magnetic media world.Until the advent of CD-burners, Zip drives were and still continue to be oneof the most popular backup devices.

Zip Drive TypesThe zip drives can be classified according to the capacities i.e. 100 MB, 250MB, 750 MB and the type of interface used by the zip drive. Zip drives canbe internal or external types. In internal type, it comes only with the ATAPI typeof interface having all the same type of connectors as that of the hard disk,as well as the jumper settings as well. In external type, it can come with aparallel or USB type of an interface

Zip Drives and CartridgesZip drives and their media were cheaper than CD burners and their media.They could be used like any other ordinary floppy drives. The media used in

these drives are called Zip cartridges or simply cartridges.These cartridges are also portable and much more stable.These Zip cartridges can store up to 100 MB of data of anykind. They are 4 inches square that is a little larger than afloppy disk and about twice as thick.

Unfortunately to read a zip cartridge (Zip media) you needa Zip drive only and not all computers have one. Soeverytime you need your information somewhere else youneed to also carry the Zip drive, the cartridges and thedrivers of course. However, with an install base of 25 millionZip drives, finding one in places that extensively shuttle databetween computers should not be too difficult. Zip drives


Fig. 25.5 Zip Drive and cartridges


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cannot really work as booting devices. You have to buy some additionalhardware or software for this purpose. If you have a SCSI drive then you needSCSI card. In addition to this you also need to have the option of "Boot fromSCSI instead of IDE" in the BIOS of your motherboard. Also, if you are lookingfor speed this is not a very viable option for you. Zip drives are comparativelyfaster in operating files but when it comes to writing large files or reading andwriting smaller files they are quite slow but definitely faster than a floppy drive.

More about Zip drivesLike floppy diskettes Zip drives also work with magnetic media and thereforeneed great care but unlike the magnetic coating on the floppy disks, the latterhas a coating of a much better quality. Due to this the head that reads theinformation on the cartridge is much smaller in size and therefore there exista greater number of tracks per sector on the cartridge and so more informationcan be stored on the same. This magnetic media is enclosed in hard plastic.And the entire cartridge comes enclosed in a plastic jewel case like CDs.

The zip drive has a read/write head with which it reads magnetic impressionson the diskette. Wings attached closely to it control the head movements. Thesewings are on opposite sides to the head so that they can travel on either sideof the disk and position the head correctly. The data is stored on concentriccircles like in case of floppy diskettes but the Zip drive uses a variable numberof sectors per track to make the optimum use of the disk space. Unlike in afloppy disk the Zip drives do not park their heads automatically when poweringdown and therefore it is better to eject the disks from the drives before shuttingthe drive or the computer.

Unfortunately till now Zip drives drivers are not built into the standard oper-ating systems as a result of which they have to be installed separately. Driversfor installing the Zip drives are normally available on either floppies ornowadays on CDs. During installation of these drivers several other utilities canalso be installed. These offer various additional features, like, if you want tochange the drive letter, or if you want to format a Zip disk, which is rare, asthese disks are preformatted.

What are Disk Arrays?Disk arrays are storage systems that link multiple physical hard drives into onelarge drive for advanced data control and security. Disk arrays have severaladvantages over traditional single-disk systems.

A hard disk, while being the vital center of any computer system, is also itsweakest link. It is the only critical device of a computer system that is notelectronic, but relies on intricate moving mechanical parts that often fail. When


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this happens, data is irretrievableand unless a backup system hasbeen employed, the user is out ofluck. This is where disk arraysmake a difference.

Disk arrays incorporate controlsand a structure that pre-emptsdisaster. The most common diskarray technology is RAID(Redundant Array of IndependentDisks). RAID utilizes disk arrays ina number of optionalconfigurations that benefit theuser.

One advantage of RAID diskarrays is redundancy of data writesso that if a file is damaged orstored in a bad cluster or disk, itcan be instantly and transparentlyreplaced from another disk in thearray. RAID also allows hot-swapping of bad disks andincreased flexibility in scalablestorage. Performance is alsoenhanced through a processcalled "striping."

There are many varieties of RAID,and though designed primarilyfor servers, disk arrays havebecome increasingly popularamong individuals because oftheir many benefits. RAID isparticularly suited for gamers andmultimedia applications.

RAID controllers, built intomotherboards, must setparameters for interacting withdisk arrays. The controller sets theperformance parameter to match


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.

the slowest disk. If it were to use the fastest disk as the benchmark, data wouldbe lost when written to disks that cannot support that speed. For this reason,all disks in the array should be the same brand, speed, size and model foroptimal performance. A mix of capacities, speeds and types of disks willnegatively impact performance. The best drives for disk arrays are SATA (SerialATA) RAID drives. These drives are optimized for RAID use and, being SATA,are hot-swappable.

Using disk arrays can provide peace of mind while improving data securityand performance. Motherboards with built-in RAID controllers support certaintypes of RAID. For example, an older or inexpensive motherboard might onlysupport RAID 0 and RAID 1, while a newer or more expensive board mightsupport RAID 1 through RAID 5. Be sure to get a motherboard or third partyRAID controller that supports the RAID configuration you require for your diskarray.

Since a backup system contains at least one copy of all data worth saving,the data storage requirements are considerable. Organizing this storage spaceand managing the backup process is a complicated undertaking. A datarepository model can be used to provide structure to the storage. In the modernera of computing there are many different types of data storage devices thatare useful for making backups. There are also many different ways in whichthese devices can be arranged to provide geographic redundancy, datasecurity, and portability.

Before data is sent to its storage location, it is selected, extracted, andmanipulated. Many different techniques have been developed to optimize thebackup procedure. These include optimizations for dealing with open files andlive data sources as well as compression, encryption, and de-duplication,among others. Many organizations and individuals try to have confidence thatthe process is working as expected and work to define measurements andvalidation techniques. It is also important to recognize the limitations andhuman factors involved in any backup scheme


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LAB EXERCISE 25.1 : Backup Data on backup devices

Objective : To be familiar with the built-in backup programs for backing updata using Hard disk, Zip Drive or Tape Drive.

Tasks:1. Open the Microsoft Backup program from the System tools tab.

2. Now, try backing up a small file such as a text file from My Documents onthe hard disk itself so that even if the system files are corrupted the data isbacked up.

3. Once backed up, then, now try recovering the file on the Desktop so that itis easily visible.

4. Now, backing up by using the Zip drive, which is ready for use afterinstalling the driver, which will get a drive letter, and then backup the MyDocuments Folder.

5. Try now recovering back the My Documents folder from the Zip drive.


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CMS COMPUTER INSTITUTE Viruses

Viruses

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What is a Computer Virus?Computer viruses are mysterious and grab our attention. Viruses show us howvulnerable we are. A properly engineered virus can have an amazing effecton the worldwide Internet.

Computer viruses are computer software programs, just as word processors,spreadsheets, database managers. They are simply lists of instructions that tellcomputers what actions to execute and precisely how to execute them. Computerviruses can, therefore, perform all operations that are supported by the hostcomputer's operating system just as any other piece of software can performthose operations.

For example, the thing making big news right now is the Mydoom worm, whichexperts estimate infected approximately a quarter-million computers in asingle day. Back in March 1999, the Melissa virus was so powerful that it forcedMicrosoft and a number of other very large companies to completely turn offtheir e-mail systems until the virus could be contained. The ILOVEYOU virusin 2000 had a similarly devastating effect. That's pretty impressive when youconsider that the Melissa and ILOVEYOU viruses are incredibly simple.

Most software programs carefully monitor and control users actions to preventfrom inadvertently damaging or losing data by displaying warning or errormessages. These alerts serves as fail-safe mechanisms against unintentionallydestructive actions. Computer viruses and other rogue programs, on the otherhand, are designed to function in a manner diametrically opposed to virtuallyall "legitimate" software programs. Viruses load and run without users requestingthem to run; they hide inside normal programs called host programs and runwhen the hosts are run. Viruses act without prompting users for permission andwithout warning users of the consequences of their actions. When virusesencounter errors, they recover or attempt to recover without printing errormessages and without asking users to assist in correcting error-related conditions.In a nut shell, computer viruses are designed to operate secretly, behind the

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scenes, so that their missions can be accomplished without, and not becompromised by, user input.

What Can Viruses do?Virus stands for Vital Information Resources Under Seize. Virus can do anythingwhich a software programs can do, but it does it secretly. It can format disks,copy, rename and delete files, clone themselves with new configurationinformation, modify file dates and attributes, call other computers to uploadand download files, and so on. If the action can be performed by computersoftware, it can be performed by a computer virus. Technically speaking virusis a program that modifies other programs to include an viral codes in it. Tomeet the minimum criteria for computer virus design the program must :

• be executable

• be capable of cloning itself

• convert other executable objects into viral clones

Nowhere in the definition of computer viruses is there any mention of nonprompted, secret operations, of destructive actions, or of spreading acrossmultiple computer installations. Rogue programmers have added those twists,but a program need not conduct such activity to qualify as a computer virusbut the important property of the virus is the replication and doing things insecrecy.

From the merely amusing to the absolutely disastrous, there is practically nolimit to what extent virus affects computing activity. The ability of viruses tocorrupt important databases and programs can cause great problems. It canalter just a small bit of data here and there, such as adding a zero to multiplycertain figures by 10 or moving a decimal point a place or two, either in acarefully calculated or a random manner. In text files, a virus may changeone name for another.

Virus can execute a normal DOS routine at the most inappropriate time sothat it causes the most harm. For example, when save a file command is given,the virus might change the command to FORMAT, destroying all the data onthe disk to the file was to be saved.

The .COM and .EXE infector viruses interrupt normal computing activity at thefirst available opportunity to take control of the system while they copythemselves to new .COM and .EXE files. They may attach to the file externally.Or they may find internal spaces that will accommodate the virus code withinthe coding for the program selected as a host.

Some of the .COM and .EXE infector remain resident in the system's memoryso that they can enter in the boot sector of a disk to make this a more

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comfortable environment for virus replication and other activity. They can alsoalter applications programs so that they are more accommodating to theneeds of the virus. A virus may seek out a system file that is already hidden,or change a file that it has infected into a hidden one that will not show upin directories. A number of viruses hide in or alter for their own purposes thesoftware that control a system's internal clock. Often one of the first actions ofa virus is to check the time and date in a system to see if these match the virus'sprogrammed activation time. Another frequent first action by a virus is to checkif there are any new files or disks accessible within the system for it to infect.If not, it may immediately pass control back to the operating system orapplication program and remain dormant until a suitable infection opportunityarises.

Viruses may run concurrently with the operating system or application programsthey have infected, carrying out their tasks either openly or hidden in thebackground. There are generic application infectors programmed to gaincontrol of application programs when these are run, make whatever changesthe virus has been instructed to do, then pass control back to the application.These viruses either hide in the application and take over some of its functionsor more frequently, attach themselves to the beginning or end of files. Virusescan prevent the user from accessing the data, even if the data is not destroyed?Showing error messages like "File not found" and "Error reading drive".

Many viruses slows down the computing operations because of the sheer loadthat their reproductive activity imposes, particularly if there are bugs in thevirus. Good example of this is the Christmas virus. But they can also be madeto do this deliberately in various ways, either to annoy users or to make thesystem virtually unusable.

Why Virus is created?With the ongoing growth in the popularity and raw processing power ofpersonal computers, more and more people have access to computers thanever before. This increased exposure has led to an explosion in the numberof talented programmers, both self-taught and professionally trained. The risein the number of computer programmer is parallel to this growth. TheComputer viruses are designed by these programmers. After the programhas been designed and compiled, programmer must build a convincing cloakthat tricks users into dumping viral code inside their uninfected computers.

People create viruses. A person has to write the code, test it to make sure itspreads properly and then release the virus. A person also designs the virus'sattack phase, whether it's a silly message or destruction of a hard disk. So whydo people do it?

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For some people that seems to be a thrill. If that sort of person happens toknow computer programming, then he or she may funnel energy into thecreation of destructive viruses.

The second reason has to do with the thrill of watching things blow up. Manypeople have a fascination with things like explosions and car wrecks. Creatinga virus that spreads quickly is a little like that -- it creates a bomb inside acomputer, and the more computers that get infected the more the fun.

The third reason probably involves bragging rights, or the thrill of doing it.Sort of like Mount Everest. The mountain is there, so someone is compelledto climb it. If you are a certain type of programmer and you see a securityhole that could be exploited, you might simply be compelled to exploit thehole yourself before someone else beats you to it.

Of course, most virus creators seem to miss the point that they cause realdamage to real people with their creations. Destroying everything on aperson's hard disk is real damage. Forcing the people inside a large companyto waste thousands of hours cleaning up after a virus is real damage. Evena silly message is real damage because a person then has to waste timegetting rid of it. For this reason, the legal system is getting much harsher inpunishing the people who create viruses.

How virus get into the system?After the virus has been created by the programmer they have to think of away how to insert this virus into other system without users knowledge. Someprogrammers use infected start-up disks or everyday program disks as viralcarriers. They distribute pirated (illegally copied) editions of expensivecommercial software using system disks that they've infected. When users bootup the contaminated disks, the embedded bugs are released and quicklyspread throughout their systems. Other programmers choose to bury their viralcode inside useful utility programs such as directory sorters or print spoolersor into any executable program . Then they distribute their softwares to trustingusers through user group disk libraries, bulletin boards, swap meets, andelectronic mail.

It is logical for viruses to be designed to enter systems through the files theyare most likely to encounter when they arrive. So the .COM, .EXE, or .SYS filesthat are part of every DOS system are the obvious targets. Other operatingsystems have similar vulnerabilities. There are also system files that are notlisted in directories, and so provide a good place for viruses to hide.

Many executable files tend to be activated during the initial booting upprocedure as soon as the computer is switched on. Consequently, many virusesare designed to attached themselves to these files because they are always

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present in DOS, they perform powerful, vital functions, and they are usuallythe first to be run every time the computer is started.

Electronic mail i.e e-mail systems are the most recently used method manyprogrammers use to spread viruses. They create virus definitions that spreadthemselves to all the members in the address list thereby spreading.

Nowadays worms are more popular than viruses. These worms or viruses arehidden in the attachment once the user clicks or downloads the attachmentthe system gets infected.

What Systems are at most risk from viruses?Nowadays all viruses are greatly made to affect the networking subsystem.Microsoft Operating systems are more prone to viruses. It is very difficult todesign a virus for Unix based system due to its internal architecture.

Nowadays 75 % of the viruses are affecting Windows NT/2000/XP and 2003operating systems.

Mailservers cannot be left behind. The latest MyDoom is in the picture.

How Viruses Spread?There are many ways for a virus to enter your system:

• Email attachments

• Database replications

• Shared network files and network traffic in general

• World Wide Web (WWW) sites

• FTP traffic from the Internet (file downloads)

• Floppy disks brought in from outside the organization

• Electronic bulletin boards (BBS)

• Pirated software

• Demonstration software

• Computer labs

The most likely virus entry points are email, Internet and network connections,floppies; modems or other serial or parallel port connections. In today’sincreasingly interconnected workplace (the Internet, intranet, shared drives,removable drives and email), virus outbreaks now spread faster and wider thanever before.

How viruses spread in the network?The latest breed of computer viruses is after LANs (Local Area Networks). Mostof them have support to attack the network operating system. Network systemoperators now face a difficult task in preventing the spread of viruses. The most

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popular LANs are Micro computer LANs.

The way the LAN normally functions is that applications are loaded on the fileserver and the users sitting at the nodes can access the files on server as if theyare on a local drive although the drive is attached to the file server.

Let's now consider file infector viruses. When a node communicates with thesever, first the TCP/IP protocol (in case of Windows) is loaded in the node'smemory, followed by the network file redirector. This is a memory residentprogram, and its function is to redirect any request for a remote drive. Allrequests for remote resources are pipelined by the redirector.

Here again, two cases arise:

• Clean files on server being infected by virus files on node.

• Clean files on node being infected by virus files on server.

In the first case, suppose after logging in, the user executes an infected file onthe node. The file infector virus attached to the file will become memory-resident and hook crucial interrupts like INT 13 H, 21 H. The user now executessome program on the server. The redirector deftly executes the program withoutOS knowing about it. Our watchful virus is sitting in the node's memory andas soon as it sees that the file being executed is an EXE file, it issues an OScall to open the file in read-write mode. The redirector interprets this call andpasses it on to the server. The virus now executes the OS calls to attach its codeto the file executed on the server. The redirector redirects these calls, so thefile on the server gets infected. However, in this situation, files executed by theserver (thus, not involving the node) would not be infected, because our virusesare memory-resident on the node. From the node, it can only infect files onserver executed from node but cannot occupy the server's memory.

In the second case, the files on server are infected. Execution of an infectedfile brings the virus into the server's memory. Now, when clean file is executedby server, it gets infected. What is an infected file on the server is accessed bythe node? Well, the redirector redirects the call, the infected file is picked upfrom server's hard disk, loaded in to the node's memory and executed. Thisexecution brings the virus code into the node's memory also. Any EXE fileexecuted on node, even if accessed from the node's local disk will now getinfected. This second case is thus the most dangerous one.

Types of VirusesThousands of viruses are known to exist with more being created each day.Computer viruses exist in Windows, OS/2, Mac, DOS, and UNIX environments.Computer viruses can be roughly classified into the following categories:

• Macro viruses

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• File viruses

• Boot viruses

• Multi-partite viruses

• Polymorphic or mutation viruses

• Stealth viruses

Macro VirusesMacro viruses are perhaps the newest type of virus. The first macro virus, writtenin Microsoft’s Word macro language, was discovered in August, 1995. Currently,thousands of macro viruses are known to exist and include viruses written inthe macro language of Microsoft’s Excel, Word and AmiPro applications.

Since a macro virus is written in the language of an application, not theoperating system (OS), it is platform independent and can spread betweenDOS, Windows, Mac, and even OS/2 systems. That is, macro viruses can bespread to any machine that runs the application the virus was written in. Anymachine running Word, for example, whether it is a PC, Mac or something else,is vulnerable to Word documents that contain a macro virus.

This in itself is revolutionary. Now add the ability to travel by email, plus thetremendous interconnections of networks, the World Wide Web and theincreasing power of the Macro language (Word, Excel, etc.), and you’ve gotyourself a real threat.

File Viruses (Parasitic Viruses)File viruses attach themselves to executable files and are at least partiallyactivated whenever the host file is run. File viruses are typically TSR (terminate-and-stay-resident), direct action or companion programs.

TSR viruses, which are among the most common of viruses, reside in memoryand attach themselves to executable programs when they are run. It is in thisway that TSR viruses spread to other programs on the hard drive, floppies ornetwork.

A direct action virus loads itself into memory to infect other files and thenunloads itself, while a companion virus acts to fool an executable file intoexecuting from a .COM file. For example, a companion virus might create ahidden PGM.COM file so that when the PGM command is executed, the fakePGM.COM runs first. The .COM file invokes its virus code before going on tostart the real PGM.EXE file.

Boot VirusesBoot-sector viruses, the most common type of virus, move or overwrite a disk’soriginal boot sector data and replace it with an infected boot code of their

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own design. Floppies and hard drives are the most susceptible to beingoverwritten by a boot sector virus. Then, whenever the infected system ispowered on (boots up), the virus loads into memory where it can gain controlover basic hardware operations. From its place in memory, a boot virus canquickly spread to any of the other drives on the system (floppy, network, etc.).

Multi-partite VirusesMulti-partite viruses share some of the characteristics of boot sector viruses andfile viruses: they can infect .COM and .EXE files, and the boot sector of thecomputer’s hard drive.

On a computer booted up with an infected floppy, a typical multi- partite viruswill first make itself resident in memory and then infect the boot sector of thehard drive. From there the virus may infect a PC’s entire environment.

Not many forms of this virus class actually exist. They do, however, accountfor a disproportionately large number of infections.

Polymorphic or Mutation VirusesPolymorphic (mutation) viruses are unique in that they are designed to eludedetection by changing their structure after each execution--with somepolymorphic viruses, millions of permutations are possible. Of course, thismakes it harder for normal antivirus programs to detect or intercept them. Itshould be noted that polymorphic viruses do not, strictly speaking, constitutea separate category of virus; they usually belong to one of the categoriesdescribed above.

Stealth VirusesStealth viruses, or Interrupt Interceptors, as they are sometimes called, takecontrol of key DOS-level instructions by intercepting the interrupt table, whichis located at the beginning of memory. This gives the virus the ability to dotwo important things:

1. take control of the system by redirecting the interrupt calls, and

2. hide itself to prevent detection.

How a Virus WorksA virus is very similar to a standard piece of software that you would pay forin the stores, but with some key differences. Unlike normal software it will installand run itself, usually to perform malicious damage, and replicate throughyour systems.

Like biological viruses, they replicate quickly and can be difficult to eliminate.They may attach themselves to almost any type of file and are spread as thesefiles are copied between people's computers.

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Besides replication, viruses have another common trait; a damage routine thatwill deploy the malicious payload. This payload could simply show a messagebox or a picture on your screen, but it could also change or delete files, formata hard disk or many other types of damage.

Before the Internet, most viruses were spread on floppy disks as they passedbetween computers, but the Internet has provided a much quicker and easierto exploit method of transferring these malicious programs. E-mail is now oneof the most commonly heard-of methods of virus replication and can spreadthrough entire enterprises in minutes, costing the companies millions of poundseach year in clean-up procedures.

Every computer virus has a lifecycle that starts when they are created andfinishes when they're completely eradicated. Below is a summary of thatlifecycle, with a description of each stage.

Stage 1 - CreationUntil a few years ago, creating a virus required a lot of complex programmingknowledge. However as computers have become easier to use and understand,only basic knowledge is required. Viruses are usually created by the misguidedindividual who wishes to cause widespread damage to computer systems.

Stage 2 - ReplicationViruses replicate themselves to cause widespread damage, and usually try toconceal their replication. Floppy disks, CD-ROMs, any other type of media,plus e-mail and web pages are all perfect replication vehicles for a virus.

Often viruses are "dormant" for a period of time after their initial release, whichmeans it can travel undetected and infect as many systems as possible before"activating" and delivering their payload.

Stage 3 - ActivationViruses that have been created to cause damage often activate on certaintriggers. It could be a time delay (as described above), or a particular actionperformed by the user or computer that has been infected.

Some viruses without damage routines don't activate, but can run repetitivetasks on your PC in the background. This could reduce the amount of availablememory on your computer, processor time or even slowly fill your hard drive.

Stage 4 - DiscoveryThis phase usually comes after activation, but not always. When a virus isdetected and isolated, it is sent to the International Computer Security Association(ICSA) in Washington, to be documented and distributed to anti-virus developers.Discovery of a virus often takes place at least a year before it actually causesa threat to the general computing community.

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Step 5 - AssimilationAnti-virus developers then deconstruct the virus to find telltale signs of it'sexistence, and how to safely remove it. Depending on the virus, this could takeanywhere from a single day to six months. Once assimilated, the virus"definition" is sent to all computers running the anti-virus software. The softwarecan then use this definition to detect it.

Stage 6 - EradicationIf enough users across the globe ran up-to-date anti-virus software, theseviruses would very easily become extinct. However at the moment no knownvirus has been completely eradicated. Luckily enough users have protectionagainst these malicious files for old viruses to not pose a significant threat.

Virus Examples :I LOVE YOU VirusAn analysis of the computer code showed that while the virus does indeeddelete files from personal computers, it multiplies itself quickly, sendingduplicates via e-mail and a program used to access Internet Relay Chat, atext based online messaging system. Because the virus accesses and sendscopies of itself to everyone in a victim's e-mail address book, it literally clogsup the Internet with junk mail, much like a plumbing clog, grinding everythingto a halt.

The virus only targets users running Microsoft Windows operating system,attacking the Outlook e-mail program and the Internet Explorer browser, bothof which are made by Microsoft.

The victim activates the virus by opening the e-mail, then clicking on theattachment inside. Opening the e-mail of its own does not activate theprogram. Once activated, the program accesses pieces of the Windowsoperating system, essentially turning on the parts of Windows it needs tospread. First, it opens the Internet Explorer Web browser and attempts todownload more virus code from one of four different web sites. The downloadedcode is then used to obtain passwords from the user's computers.

Finally, it goes into Microsoft Outlook's address book and creates e-mailduplicates of itself, sending the virus to everyone in the address book. If theuser has the e-mail-to-fax function activated, the virus is sent via fax, thoughthe program is actually printed out as computer code, which presents nodanger to the fax machine.

The best defence, experts said, is to simply leave any unusual or unknownattachments unopened. Instead of clicking on them, just delete the entire e-mail.

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Code RedWorms use up computer time and network bandwidth when they are replicating,and they often have some sort of evil intent. A worm called Code Red madehuge headlines in 2001. Experts predicted that this worm could clog theInternet so effectively that things would completely grind to a halt.

The Code Red worm slowed down Internet traffic when it began to replicateitself, but not nearly as badly as predicted. Each copy of the worm scannedthe Internet for Windows NT or Windows 2000 servers that do not have theMicrosoft security patch installed. Each time it found an unsecured server, theworm copied itself to that server. The new copy then scanned for other serversto infect. Depending on the number of unsecured servers, a worm couldconceivably create hundreds of thousands of copies.

The Ida Code Red Worm, which was first reported by eEye Digital Security, istaking advantage of known vulnerabilities in the Microsoft IIS Internet ServerApplication Program Interface (ISAPI) service. Un-patched systems aresusceptible to a "buffer overflow" in the Idq.dll, which permits the attacker torun embedded code on the affected system. This memory resident worm, onceactive on a system, first attempts to spread itself by creating a sequence ofrandom IP addresses to infect unprotected web servers. Each worm thread willthen inspect the infected computer's time clock.

Upon successful infection, the worm would wait for the appointed hour andconnect to the www.whitehouse.gov domain. This attack would consist of theinfected systems simultaneously sending 100 connections to port 80 ofwww.whitehouse.gov (198.137.240.91).

The U.S. government changed the IP address of www.whitehouse.gov tocircumvent that particular threat from the worm and issued a general warningabout the worm, advising users of Windows NT or Windows 2000 Web serversto make sure they have installed the security patch.

W95.CIHThe CIH virus, also known as Chernobyl, was first discovered in June 1998 inTaiwan. According to the Taipei authorities, Chen Ing-hau wrote the CIH virus.The name of the virus derived from his initials.

CIH is a destructive virus with a payload that destroys data. On April 26, 1999,the payload triggered for the first time, causing many computer users to losetheir data. In Korea, it was estimated that as many as one million computerswere affected, resulting in more than $250 million in damages.

CIH is a virus that infects the 32-bit Windows 95/98/NT executable files, butcan function only under Windows 95/98 and ME. It does not function underWindows NT or Windows 2000. When an infected program is run under

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Windows 95/98/ME, the virus becomes resident in memory.

Although Windows NT system files can be infected, the virus cannot becomeresident or infect files on a computer running Windows NT or Windows 2000.The virus does not function under DOS, Windows 3.1, or on Macintoshcomputers. Once the virus is resident, the CIH virus infects other files whenaccessed.

The files infected by CIH may have the same size as the original files, due tothe unique infection mode of CIH. The virus searches for empty, unused spacesin the file. Next, it breaks itself up into smaller pieces and inserts its code intothese unused spaces.

W32.Blaster.WormW32.Blaster.Worm is a worm that exploits the DCOM RPC vulnerability (firstdescribed in Microsoft Security Bulletin MS03-026) (users are recommendedto patch this vulnerability by applying Microsoft Security Bulletin MS03-039)using TCP port 135. The worm targets only Windows 2000 and Windows XPmachines. While Windows NT and Windows 2003 Server machines arevulnerable to the afore mentioned exploit (if not properly patched), the wormis not coded to replicate to those systems. This worm attempts to downloadthe msblast.exe file to the %WinDir%\system32 directory and then execute it.W32.Blaster.Worm does not have a mass-mailing functionality.

The worm also attempts to perform a Denial of Service (DoS) on the MicrosoftWindows Update Web server (windowsupdate.com). This is an attempt toprevent you from applying a patch on your computer against the DCOM RPCvulnerability.

Systems Affected are Windows 2000, Windows NT, Windows Server 2003,Windows XP

[email protected]@mm is a mass-mailing worm that searches the Windowsaddress book for email addresses and sends messages to all the recipientsthat it finds. The worm uses its own SMTP engine to send the messages.

The subject and attachment name of the incoming e-mails are randomlychosen. The attachment will have one of the extensions: .bat, .exe, .pif, or .scr.

The worm exploits a vulnerability in Microsoft Outlook and Outlook Expressto try execute itself when you open or preview the message.

Email spoofing: Some variants of this worm use a technique known as"spoofing" by which the worm randomly selects an address it finds on aninfected computer. The worm uses this address as the "From" address when itperforms its mass-mailing routine. Numerous cases have been reported in

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which users of uninfected computers received complaints that they sent aninfected message to another individual.

For example, Trishal R. Doshi is using a computer infected with [email protected] is neither using an antivirus program nor has the current virus definitions.When W32.Klez.gen@mm performs its email routine, it finds the email addressof Dilip Davis. The worm inserts Dilip's email address into the "From" portionof an infected message, which it then sends to Ajay Harsora. Then, Ajaycontacts Dilip and complains that he sent him an infected message; however,when Dilip scans his computer, Norton AntiVirus does not find anything,because his computer is not infected.

If you are using a current version of Norton AntiVirus and you have the mostrecent virus definitions, and a full system scan with Norton AntiVirus, which isset to scan all the files, does not find anything, your computer is not infectedwith this worm.

Systems Affected by this virus are Windows 95, Windows 98, Windows NT,Windows 2000, Windows XP, Windows Me.

[email protected]@mm (also known as W32.Novarg.A) is a mass-mailingworm that arrives as an attachment with the file extension .bat, .cmd, .exe, .pif,.scr, or .zip.

When a computer is infected, the worm sets up a backdoor into the systemby opening TCP ports 3127 through 3198, which can potentially allow anattacker to connect to the computer and use it as a proxy to gain access toits network resources.

In addition, the backdoor can download and execute arbitrary files.

There is a 25% chance that a computer infected by the worm will perform aDenial of Service (DoS) on February 1, 2004 starting at 16:09:18 UTC, whichis also the same as 08:09:18 PST, based on the machine's local system date/time. If the worm does start the DoS attack, it will not mass mail itself. It alsohas a trigger date to stop spreading/DoS-attacking on February 12, 2004.While the worm will stop on February 12, 2004, the backdoor component willcontinue to function after this date.

Systems Affected are Windows 2000, Windows 95, Windows 98, Windows Me,Windows NT, Windows Server 2003, Windows XP.

Protection Against VirusesYou can protect yourself against viruses with a few simple steps:

If you simply avoid programs from unknown sources (like the Internet), andinstead stick with commercial software purchased on CDs, you eliminate

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almost all of the risk from traditional viruses. In addition, you should disablefloppy disk booting -- most computers now allow you to do this, and that willeliminate the risk of a boot sector virus coming in from a floppy diskaccidentally left in the drive.

You should make sure that Macro Virus Protection is enabled in all Microsoftapplications, and you should NEVER run macros in a document unless youknow what they do. There is seldom a good reason to add macros to adocument, so avoiding all macros is a great policy.

You should never double-click on an attachment that contains an executablethat arrives as an e-mail attachment. Attachments that come in as Word files(.DOC), spreadsheets (.XLS), images (.GIF and .JPG), etc., are data files andthey can do no damage A file with an extension like EXE, COM or VBS is anexecutable, and an executable can do any harm and thus they should not bedouble-clicked.

Anti Virus TechnologiesAnti Virus solutions have deviced a variety of techniques to detect, cure andimmunise against viruses. Each of these technologies has its advantages anddrawbacks. These technologies are constantly being modified and refined tobe effective against the new viruses that are continuously being written.

Virus detection using SignaturesA virus writer writes a virus using a specific logic. The logic used to write a virusdistinguishes it from other viruses. The logic for a virus program has a uniquesequence which is known as the signature of the virus.

An anti virus software uses this signature to detect the virus. While selecting asignature from a virus the anti virus developer should take care that the sequenceis long and unique enough so that it does not cause any false alarms.

The draw back of this method isIt cannot detect new viruses until the virus signature database is updated todetect the new virus. As viruses increase the signature database grows so largethat the time taken to scan for viruses is very large. Polymorphic viruses, whichmutate continuously are difficult to detect.

Virus detection using TSR Guards :Anti virus softwares use TSR (Terminate and Stay Resident) programs to detectand prevent virus like activity. The TSR acts like a guard checking all activityon the computer. When the TSR detects an activity that it feels is suspicious itgives an alarm to the user. The user should respond to the alarm.

The draw back of this method isThe computer is slowed down because every activity is checked by the TSR.

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TSR's occupy memory. The user should understand every alarm given by theTSR and should respond correctly. Any wrong response would cause the virusto spread on the computer making the TSR ineffective.

TSR Guards are ineffective in non technical computer environments becausethe user may not respond correctly.

Virus detection using Checksums:Anti virus softwares use checksums of programs to detect if a program isinfected. A checksum is a number generated by using the complete contentsof the file. The checksum is unique to every file. A single one byte change willresult in a change in the checksum. The anti virus software first calculates andstores a checksum for every program on the disk. It later compares the currentchecksum program against its previously stored checksum. A change wouldbe taken as a virus infection.

The draw back of this method isAny change in the checksum is taken as a virus infection. Legitimate changes likerecompilation is also confused as a virus, resulting in false alarms.

Updates to softwares is also confused as a virus, resulting in false alarms. Cannotbe used in development environment.

What to look for in an Anti-virus Software

Q. Does the anti-virus package come with a DOS boot disk and does it askyou to create an emergency repair disk during installation?

A. It is essential that the package comes with a DOS boot disk and asks theuser to create an emergency repair disk during installation. These diskscome in handy when the system is attacked by a virus that does not allowthe OS to load. Using the DOS boot disk, one can boot the system andrun the virus cleaning procedure through DOS. The emergency repair diskmaintains a copy of the system's Master Boot Record (MBR) as well as start-up files such as io.sys, msdos.sys and command.com. In case the systemMBR is destroyed, it can be replaced using this disk.

Q. Does the anti-virus package offer option for scanning the boot record anda complete file scan immediately after pre-install scan?

A. Very often, users install an anti-virus package after their machines arealready infected. It is very essential for the anti-virus package to offer theoption of scanning at least the boot records during the installation process.Once the installation is complete, the software should offer to scan theMaster Boot Record as well as all files at start-up to ensure that the virusis removed before you perform any other operations.

Q. Does the application check for file integrity?

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A. Certain viruses, when infecting a particular files, change the size of the file.The change could be either an apparent increase or decrease in the filesize. When an anti-virus software checks files for viruses, it uses methodssuch as checksum, and CRC (cyclic redundancy check) to keep a checkon file integrity. They take a 'fingerprint' of each file and store it in anintegrity file. Later, the file is examined and its fingerprint matched with thestored version.

Q. How often can the user download virus signature updates?

A. Anti-virus software developers should have the latest virus signature fileson their Web site for download as soon as a new virus is discovered. Theyshould provide users with regular newsletters via e-mail, informing themabout the posting of the signature update files. This will allow users toupdate their version of the application and ensure that new viruses do noteffect their machine.

Q. Does the anti-virus software have the option of performing a heuristicanalysis?

A. A heuristic analysis is a method of detecting viruses that have the capabilitiesof changing their signatures with each infection in an attempt to avoiddetection. As far as possible, select the 'heuristic analysis' option beforeperforming a virus scan.

Q. Is the anti-virus package capable of analysing and disinfecting compressedarchives such as .ZIP and .ARJ files, as well as disinfecting files within thearchive?

A. Many good anti-virus programs can detect and disinfect most knownviruses but it is very essential for the software to be capable of scanningand disinfecting infected files within a compressed archive. If files fromwithin the archive need to be extracted for scanning, there is a possibilitythat the user might accidentally execute an infected file.

Different Antivirus SoftwaresAntivirus software is must-have protection. When you're seeking total systemcoverage each of the following anti virus mentioned below provides superbvirus protection for Windows-based PCs. Because every system is unique,evaluate several of these antivirus products to find the software best suited foryour PC and your level of experience.

PC-cillin Internet Security Suite 2004Trend Micro PC-cillin Internet Security provides comprehensive and easy to useprotection from viruses, hackers, and other Internet-based threats. Its newadvanced features go far beyond standard antivirus and firewall protection,

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helping to safeguard your PC from new emerging threats like network viruses,spam email, inappropriate web content, and Spyware programs that cancompromise your privacy.

The new Network Virus Emergency Center provides the most advanced protectionfrom today’s fast spreading network viruses such as MSBLAST, SOBIG, andCode Red. It proactively warns users about new network virus outbreaks andscans for these viruses at the network firewall level where they attempt topenetrate your PC. If network virus activity is detected it can automaticallyinvoke the Internet Lock feature stopping the virus from infecting the PC andspreading to other computers.

PC-cillin Internet Security also now includes a powerful new anti-spam scannerthat detects and flags annoying and potentially dangerous junk email. Forpeople on the go, the Firewall Profiles feature allows you to quickly adjustsecurity control levels for your different network environments such as home,work, Wi-Fi, and on the road. As always, Trend Micro PC-cillin Internet Securityis backed by award-winning technical support.

FeaturesComprehensive Virus Detection and RemovalTrend Micro PC-cillin Internet Security helps make the detection and removalof viruses more precise and powerful. The enhanced Personal Firewall helpsprevent intrusion from hackers and the new breed of Network Viruses. TrendMicro Damage Cleanup Services can now be triggered as soon as a virus iscaught to keep your system functioning properly.

Enhanced Network Virus ProtectionWith the Network Virus Emergency Center, consumers can now get the samelevel of protection as big corporations from network viruses such as KLEZ,MSBLAST, and SOBIG. If a network virus is detected, Trend Micro PC-cillinInternet Security can automatically shut off the PC’s network access, stoppingthe spread of the virus.

Anti-Spam FilteringUsers can now configure Trend Micro PC-cillin Internet Security to identify andblock unsolicited and junk e-mails. Filtering sensitivity can be set for High,Medium, or Low based on personal preference.

URL Filtering and Parental ControlManage the sites your family can view with Parental Control, also known asURL Filtering. Permitted lists and restricted lists can block or allow connectionsto Web sites you deem appropriate.

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Advanced Privacy and Spyware ProtectionTrend Micro PC-cillin Internet Security helps prevent third parties from monitoringyour Internet use and blocks malicious programs and websites from accessingyour personal information. Spyware Protection is designed to detect andremove annoying Spyware programs from tracking your surfing behaviours,stealing passwords or account information, and creating dangerous backdoors into your system.

Panda Antivirus Platinum v7.0An innovative security solution that adapts perfectly to the needs of today'ssmall businesses and professionals , protecting information from viruses andhackers with a single product.

FeaturesEliminates all types of viruses.Panda Antivirus Platinum 7.0 detects and eliminates all types of viruses, Trojanhorses, worms, malicious ActiveX controls and Java applets. Thanks to itsadvanced technology, it is effective against new, unknown viruses. Install it andprevent any nasty surprises when sending and receiving e-mails, downloadingfiles or working on the Internet.

Protects against hackers: includes firewall protection.Panda Antivirus Platinum 7.0 incorporates a latest generation firewall thatstops hackers from destroying, stealing or corrupting your information. Turningyour computer into a fortress against Internet threats, keeping data in andunwanted viruses out.

Completely automatic daily updates against new viruses.Panda Antivirus Platinum 7.0 discreetly utilizes your Internet connection toautomatically incorporate new updates against new viruses.This process is fast and transparent, so you can continue to work withoutdistractions. And don't forget that all registered Panda Software clients haveaccess to daily automatic updates against viruses.

Maximum speed and stability.Your time is money! Panda Antivirus Platinum 7.0 respects the normal workingfunctions of your computer while its Ultrafast engine exhaustively scans anddisinfects the entire system. Platinum 7.0 will keep your information safe andyou won't even notice it's there.

McAfee VirusScan 2004Trusted by over 2 million satisfied users worldwide, McAfee VirusScan protectsyour PC, files and email address book from high-risk, productivity-killing

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viruses, worms and trojans like Bugbear, Slammer, Code Red, Nimda, SirCamand Nicehello.Easy to use and always on guard, VirusScan automatically checks for virusupdates and software updates. So your protection is always up-to-the-minute.And it's from McAfee Security, the most trusted name in online security.

Features

Email ScanningVirusScan automatically scans inbound (POP3) and outbound (SMTP) emailand email attachments for most popular email clients, including MicrosoftOutlook, Outlook Express, Netscape Mail, Eudora, Pegasus and others.

Instant Message ScanningVirusScan scans Instant Message attachments sent via AOL Instant Messenger,Yahoo Messenger and Windows Messenger.

ScriptStopperMany of the fastest spreading viruses, like I Love You, use scripts to infect yourPC. ScriptStopper detects then stops these threats.

WormStopperWormStopper stops mass-mailing worms like Sobig by detecting activity thatmay indicate a new, undetected worm which is active on your PC. Like emailsent to more than 40 recipients or more than five e-mails sent in less than 30seconds.

Detects SpywareProtecting loss of data and privacy, VirusScan detects potentially maliciousdesktop applications like spyware, adware, Web dialers and more.

Windows Explorer integrationAccess VirusScan directly by selecting files and clicking the VirusScan icon inthe Windows Explorer window.

MS Outlook ScanningVirusScan integrates directly on the MS Outlook toolbar for instant, on-demandscanning of older email or folders.

Silent UpdatingVirusScan silently updates virus definitions (DATs), without interrupting yourwork, ensuring your computer is always up-to-date.

Symantec Norton Antivirus 2004Symantec's Norton AntiVirus 2004 is the world's most trusted antivirus solution.

• It protects email, instant messages, and other files by automatically

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removing viruses, worms, and Trojan horses. New built-in features alsodetect certain non-virus threats such as spyware and keystroke loggers.

Features

• Expanded threat detection alerts you to certain non-virus threats such asspyware and keystroke logging programs.

• Scans compressed file archives before you open them and risk infectingyour computer. (Not available on Windows Me/98.)

• Includes product activation procedure to ensure authenticity.

• Automatically removes viruses, worms, and Trojan horses.

• Scans and cleans both incoming and outgoing email messages.

• Detects and blocks viruses in instant message attachments.

• Downloads new virus protection updates automatically to protect againstnew threats.

• Worm Blocking detects worms such as “Nimda” in outgoing mail.

• Script Blocking defends against fast-moving script-based viruses such as“ILoveYou” and “Anna Kournikova.”

• Worm Blocking and Script Blocking can detect new threats even before virusprotection updates are created for them.

LAB EXERCISE 26.1 : Virus Scanning using Anti-Virus Software

Objective: To be familiar with different Anti-virus software and the common charac-teristics which are present on all of them.

Tasks:1. After installing one of the common Anti-virus software mentioned above, scan the

entire computer for viruses.2. Once scanned, it will give a list of the files repaired as well as quarantined files, in

that case what do the quarantined files mean.3. Try scheduling a scan and verify whether it works out.4. Try the Startup scan option and verify whether it affects the normal operation of

the PC.5. Perform the liveupdate of installed antivirus software.

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CMS COMPUTER INSTITUTE Laptop & Palmtop ComputersCMS COMPUTER

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27PC ENGINEERING

Types and Classes of Portable ComputersThree basic form factors describe most of the PC-compatible portable computerson the market today:

Laptops, Notebooks, and Subnotebooks. A fourth type, are the hand-held/palmtops. The definitions of the first three types are fluid, with the optionsavailable on some systems causing particular models to ride the cusp of twocategories. The categories are based primarily on size and weight, but thesefactors have a natural relationship to the capabilities of the system becausea larger case obviously can fit more into it.

LaptopsAs the original name coined for the clamshell-type portable computer, thelaptop is the largest of the three major form factors. Typically, a laptop systemweighs 7 pounds or more and is approximately 9×12×2 inches in size,although the larger screens now arriving on the market are causing all portablesystem sizes to increase. Originally the smallest possible size for a computer,laptops today have become the high-end machines, offering features andperformance comparable to a desktop system.

Indeed, many laptops are being positioned in the marketeither as desktop replacements or as multimedia systemssuitable for delivering presentations on the road. Becauseof their lesser weight, laptops typically are used by salespeople and other travellers who require the features theyprovide.

However, many high-performance laptops are now beingissued to users as their sole computer, even if they travelonly from the office to the home. Large active-matrixdisplays, with 64MB–256MB of RAM, and hard drives ofup to 20GB or more in size are all but a reality, withvirtually all systems now carrying fast CD-ROM or DVD

Laptop & Palmtop Computers


Fig. 27.1 Laptop

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CMS COMPUTER INSTITUTE Laptop & Palmtop Computers

drives; onboard speakers; and connectivity options that enable the use ofexternal display, storage, and sound systems. Some models even includecombo DVD-CD/RW drives and wireless Wi-Fi network capabilities.

To use them as a desktop replacement, you can equip many laptops with adocking station (or a less expensive port replicator) that functions as the user’s“home base,” enabling connection to a network and the use of a full-sizemonitor and keyboard.

For someone who travels frequently, this arrangement often works better thanseparate desktop and portable systems, on which data must continually bekept in sync. Naturally, you pay a premium for all this functionality. Cutting-edge laptop systems can cost at least twice the price of a comparable desktop.

NotebooksA notebook system is designed to be somewhat smaller than a laptop in nearlyevery way: size, weight, features, and price. The dividing line between whatwe might call a notebook or laptop system is somewhat fuzzy. You’ll find thatthese categorizations are somewhat flexible. Weighing 5–7 pounds, notebookstypically have smaller and less-capable displays and lack the high-endmultimedia functions of laptops, but they need not be stripped-down machines.Many notebooks have hard drive and memory configurations comparable tolaptops, and virtually all are equipped with CD-ROM or DVD drives and soundcapabilities.

Designed to function as an adjunct to a desktop system rather than areplacement, a notebook can actually be used as a primary desktopreplacement for all but the most power-hungry users.

Notebooks typically have a wide array of options because they are targetedat a wider audience, from the power user who can’t quite afford (or who doesn’twant the size and weight of) the top-of-the-line laptop to the bargain hunterwho requires only basic services.

SubnotebooksSubnotebooks are substantially smaller than both notebooks and laptops andare intended for users who must enter and work with data on the road, as wellas connect to the office network. Weighing 2 to 2.5kgs., and often less thanan inch thick, the subnotebook is intended for the traveller who feelsoverburdened by the larger machines and doesn’t need their high-endcapabilities.

Usually, the first component omitted in a subnotebook design is the internalfloppy drive, although some include external units. You also will not find CD-ROM drives and other bulky hardware components built in, although some

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machines, such as IBM’s ThinkPad X21, use a detachable module (or “slice”)that fits under the main system to carry CD-ROM or DVD drives and floppydrives. However, many subnotebooks do include large, high-quality displays,plenty of hard drive space, and a full-size keyboard (by portable standards).

As it is common in the electronics world, devices become more inexpensiveas they get smaller, but only up to a certain point at which small size becomesa commodity and prices begin to go up. Some subnotebooks are intended(and priced) for the high-end market, such as for the executive who uses thesystem for little else but email and scheduling but who wants a lightweight,elegant, and impressive-looking system. Subnotebooks range in pricedepending on features.

Different Laptop BrandsThere are several vendors for laptops available. Few of them are listed below

• Compaq • IBM Think Pads • Toshiba

• DELL • Acer

Desktop v/s laptop:First of all, a big misconception about laptops needs to be removed. Laptops,if purchased correctly, do not need a desktop to function. Laptops are "desktopreplacements", that is they replace desktops. There is no need to purchase adesktop, if you have a laptop. Almost everything a desktop can do, a laptopcan do.

However, a laptop has some fundamental differences from a desktop. One ofthese is expandability. If you purchase a laptop, there is only so much you canchange or upgrade at a later time. Desktops do not have this limitation.Everything in a desktop can be replaced.

Another fundamental difference is price. A laptop is portable, but you pay forthis portablity in upfront purchase price. Laptops will cost additional price overa similar desktop system. This additional cost is due to the laptop specificcomponents such as batteries, specialized hard drives and other laptopspecific hardware.

Palmtop (Handheld Mini-Notebooks)The rarest category (at least outside of Japan these days) is the palmtop PC.Not to be confused with the PDAs (such as the Palm or Handspring series) orthe PocketPC, these handheld mini-notebook computers run Windows 9x anduse standard applications and external accessories. Palmtop computers aretypified by the Libretto series from Toshiba (now discontinued outside of Japanbut still available on the used market in North America). Librettos weigh abouta kilogram, feature a built-in hard disk, have screens of 8 inches or less in size,

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and offer a tiny keyboard with an integral TrackPoint device.

These systems don’t offer the faster or more power-hungry Pentium II/III/Celeron processors but are fully functional PCs that run normal Windows andnormal applications using various Pentium-class CPUs. Some of the newestJapan-market Librettos use the Transmeta Crusoe processor, which can emulatePentium and similar x86 CPUs. If you can find a palmtop on the used orrefurbished market, this type of system is ideal as a secondary system forsomebody who travels and demands the smallest and lightest, yet fullyfunctional, PC.

Palmtops such as the Libretto offer a standard layout of keys, but with the keysspaced much more closely together than with a standard keyboard. As such,this class of system is very difficult to use for extensive typing, but for simplefield work, email, or Internet access—or anything that doesn’t require a lot ofdata entry—they are incredibly useful.

Personal Digital AssistantsIntroductionPersonal Digital Assistants (PDA's) are small portable handheld computers thatorganize data, such as your schedule, address book, appointment calendarand to-do list. PDA's are also designed to work with your desktop PC byconnecting the two devices with a serial cable. Your PDA will include softwarethat will manage tasks on your desktop PC and synchronize tasks with yourPDA.

Before you buy your PDA you need to consider a variety of factors. Do youwant just a basic electronic pocket organizer with personal informationmanagement (PIM) functions? Do you need to coordinate your information withothers who are connected through a network? Will you need to download e-mail and other information from the Internet to your PDA? Will you need your

PDA to take down notes during meetings? Will you need a larger PDA witha bigger screen and more memory, or will you want to travel with your PDAin your pocket?

If you know how you expect to use your PDA it will help you decide whatsize, display type, amount of memory, operating system, handwriting software,power source and other amenities you'll need.

Size of PDA'sThe size of a PDA can range from that of a credit card to a notebookcomputer. The number of features and the computing power usually increasewith the size. Credit card size units typically offer only basic PIM functionsand have about 512Kb of RAM. Because the units are so small, the screen

may be difficult to read, and there's little room for buttons, so entering data


Fig. 27.2 PDA

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can be tedious or require you to connect to a desktop PC and to use the PC'skeyboard.

Palm size computers are the most popular PDA. In fact, many people consider"PDA" and "palm computer" to be synonymous. Smaller than a paperback butlarger than a deck of cards, palm computers fit easily in the palm of your hand.The units are too small to include a keyboard, so you enter commands anddata by pressing surface mounted buttons or by tapping the display with astylus. Most PDA's also let you "write" text and include some sort of handwritingrecognition software - a few even recognize spoken commands.

Larger handheld PDA's range in size from a thick checkbook to a smallnotebook computer. These units have room for more memory and expansionslots, a half height or even full size VGA display and a keyboard with touchtype capabilities. With increased size you get increased computing power andversatility, but you lose the advantages of pocket portability. These larger unitsalso usually cost more than smaller ones.

Operating Systems for PDATwo operating systems dominate the PDA market - Microsoft's Windows CE and3Com's Palm OS. Usually Windows CE devices have more memory andfunctionality. The Windows CE operating system comes with a large set ofstandard applications and its interface uses a variation of the familiar Windowsdesktop. The standard applications are Microsoft Pocket Outlook which includesCalendar, Contacts, Tasks, and Inbox (which sends and receives e-mail),ActiveSync (which synchronizes data with your PC), Calculator, Channels (whichdownloads information from the Internet), Connections (which provides Internetaccess and communications), PC Link, Solitaire and Voice Recorder. The PDAmanufacturer may add other applications as well.

Devices based on 3Com's Palm operating system tend to operate faster -starting up faster after you turn them on, running applications and finding datafaster etc. They have a reputation for being easy to set up, learn, and use, andhave a much longer battery life. They are also known for their popular PIMapplications and extensive support from third-party developers, with thousandsof software, shareware, and freeware titles to choose from. The PIM applicationsinclude Date Book, Address Book, Mail, To-Do List, Memo Pad, Expense, andCalculator, along with Security, Games, and HotSync technology (synchronizesdata with your PC).

PDA display typesPDA's use displays that are smaller versions of those used in notebookcomputers, but as PDA's are small the display usually covers most of the frontof the unit and is therefore the most visible feature. It's important to have a

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display that's as bright and legible as possible on a PDA that is within yourbudget. A typical palm size PDA has a resolution of 320 x 240 pixels with fourshades of grey. More expensive colour models offer 256 colors. Nearly allPDAs have a liquid crystal display (LCD), backlit touch-screen with a stylus fortapping commands, selecting items, and writing text.

Monochrome LCD is the least expensive and most energy-efficient choice,providing greyscale images and text.

Passive matrix is a type of LCD color display on mid-level units that providesgood color images when you view it straight on. There are three types ofpassive-matrix displays (i) double-layer supertwist nematic (DSTN); (ii) colorsuper-twist nematic (CSTN); (iii) High-Performance Addressing (HPA). Recentimprovements in CSTN make it a great budget alternative to active matrix.

Active matrix, also called "thin film transistor" (TFT), is the brightest, sharpest,clearest, and most expensive type of LCD flat panel display that is practicalfor PDA's.

Memory requirement for PDAPDA's are usually supplied with 512-Kb of system RAM in credit card modelsand up to 16 MB in larger models. Many models also provide expansion slotsfor more memory. The operating system and built-in application programs arestored in ROM. To enable you to upgrade some manufacturers place theoperating system in a socketed ROM module which can be removed from itssocket and replaced with a new one. Other manufacturers use flash memorywhich can be erased and reprogrammed but will not erase when the poweris disconnected.

Some PDA's include slots for CompactFlash cards. These 50-pin cards aresimilar in function to, but much smaller than, the 68-pin PCMCIA PC cards thatare so popular in laptop and notebook computers. CompactFlash cardsprovide up to 96 MB (and growing) of data storage, but their small, light,energy-efficient design make them ideal for PDA's. (With an appropriate 50-to-68 pin adapter, a CompactFlash card can be used in a PCMCIA Type IIslot).

Some larger handheld PDA's include PCMCIA slots for PCMCIA cards. Thereare three types of PCMCIA cards and slots:- Type I, Type II and Type III.

Type I cards are 3.3 millimetres thick and are used mostly as additional ROMor RAM. Type II cards are 5.5 millimetres thick and used mostly as modems.Type III cards are 10.5 millimetres thick and used mostly as virtual disk drivesbut most PDA's are not large enough to accommodate these.

A Type I slot holds one Type I card; a Type II slot holds one Type II card ortwo Type I cards. A Type III slot holds one Type III card or one Type I and one

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Type II card.

Data Transfer from PC to PDAThe most common method for transferring data to your desktop PDA/PC isvia a cable through a serial port. However, many PDA's can communicate witheach other through an infrared port. These ports use the same technology asthe remote control for your TV or VCR but with a higher data transfer rate (aboutthe same rate as a parallel port). The infrared port on a PDA should conformto the IrDA standard specified by the Infrared Data Association. Any two PDA'srunning the same operating system, in close proximity, and in a straight lineof sight to each other should be able to exchange data through their IrDA ports.

Inserting text into a PDALarger PDA's have actual keyboards but medium and small PDA's require youto enter information through the touch screen with the stylus. Most systems letyou tap letters on an on-screen "keyboard" or write letters on an on-screentablet. Palm OS and Windows CE come with handwriting recognition softwareie. Graffiti and Jot which allow you to print letters individually. However, youmust form your letters precisely according to the software's rules, which cantake some time to adjust to. Some PDA's come with natural handwritingrecognition software. Instead of following the software's rules for writing letters,you train the software to recognize your own handwriting. The advantage isthat you don't have to learn the PDA's writing rules - the disadvantage is thatnatural handwriting recognition is less accurate, although the accuracy mayimprove with training.

Power sources for PDAMore memory, CompactFlash cards, color screens, voice recording--there aremany cool features and accessories for PDAs, but they need battery power towork. Most PDAs come with either alkaline batteries (usually AA size) or arechargeable battery pack. Many also include a small backup battery toprotect the memory when your main batteries run out. One set of alkalinebatteries usually lasts a few weeks with normal use; rechargeable battery packstypically last several hours between charges. And not by coincidence, the PDAsthat come with rechargeable battery packs usually consume more power thanthose that come with only alkaline batteries. Many PDAs have power-management settings to help the batteries last longer. For example, you canset the backlight or the PDA itself to turn off after a few minutes of idle time.

The most common types of rechargeable battery packs are nickel cadmium(NiCad), nickel metal hydride (NiMH), and lithium ion. A larger PDA may havea smart battery pack that provides the PDA with information about its powerstatus so that the PDA can conserve power intelligently.

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Accessing e-mail and Internet on a PDAMany PDAs are designed with the assumption that you'll check e-mail throughyour desktop PC and download the messages to your PDA for future reading.You can also download Web magazines, audio programs, and news subscriptionservices if your PDA supports these features. However, some PDAs include abuilt-in modem or a slot where you can add one, allowing you to send andreceive e-mail directly. Setting up a PDA to work with an Internet ServiceProvider's (ISP) e-mail server can be a tedious, time-consuming process--especially if you've never done it before--but you should only have to do it once.One reason for the added time and complication is that the communicationsoftware on many PDAs is less sophisticated and has fewer automatic setupconveniences than the corresponding software on desktop PCs.

Before setting up the PDA, you need your e-mail address, password, ISP's dial-up telephone number, and the following information about your e-mail system:your protocol to receive e-mail; your incoming-mail server name; your outgoing-mail server name; and your primary and secondary DNS name server addresses.You may also need to know if your ISP wants you to use IP header compressionor to enable software compression.

You can find this information on your ISP's Web site or by contacting itscustomer service department. Among the PDAs that support e-mail directly,most work with POP3, IMAP4, SMTP, and LDAP protocols, with POP3 being themost common.

Larger PDAs based on Windows CE may include Pocket Internet Explorer, aslimmer version of Microsoft Internet Explorer. Tapping your stylus on a touchscreen that's running Pocket Internet Explorer is a convenient and fun way tosurf the Web, but don't expect to watch streaming videos or to listen to soundclips; these functions are not yet supported.

How Tablets Work

When Steve Jobs ended years of speculation in 2010 by announcing the iPadtablet device, he helped launch a new era in computer hardware. Thoughtablet PCs have been around for years, the iPad was the first device to use theform factor successfully in the consumer market. And Apple's success benefittedother companies as well as tech enthusiasts looked for alternatives to Apple'sapproach.

So what exactly is a tablet? At its most basic level, a tablet PC is a mobilecomputing device that's larger than a smartphone or personal digital assistant.There's not a strict cutoff size for tablet devices -- the iPad line sports a screensize of just under 10 inches but other tablets can be larger or smaller. In

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general, if the computing device uses an on-screen interface and doesn'tinclude a phone, it's a tablet.

To confuse matters, some manufacturers produce hybrid devices that are parttablet, part laptop computer. The device might come with an attached keyboard-- the screen swivels or folds down to cover the keyboard and voila, you havea tablet!

In 2010, Lenovo introduced a prototype device called the IdeaPad U1 at theConsumer Electronics Show in Las Vegas, Nev. At first glance, it looked likea normal laptop computer. But if you detached the screen from the base, thelaptop converted to a tablet computer with its own, independent operatingsystem. Lenovo rebranded the device, naming it the Lenovo LePad andlaunching it in China in 2011.

Although tablets come in a variety of shapes, sizes and feature sets, they sharemany similar characteristics. Nearly all have a touch-screen interface and anoperating system capable of running small programs. They don't necessarilyreplace the need for a more robust computer, but they create a new space forcomputing devices.

What Makes Tablets TickIf you were to crack open a tablet computer to take a look inside, you'dnotice three things pretty quickly. First, you've just voided your warranty.Second, the manufacturer has packed all the tablet's components togetherto create a snug, efficient fit. And third, most of the components you'll seeare similar to what you'd find in a standard computer.

The brain of a tablet is its microprocessor. Typically,tablets use smaller processors than full-fledgedcomputers. This helps save on space and cuts down onheat generation. Heat is bad for computers -- it tends tocause mechanical failures.Tablet computers typically draw power from arechargeable battery. Battery life for tablets varies betweenmodels, with eight to 10 hours being the average. Sometablets will have replaceable batteries. But others, likeApple's iPad and iPad 2, don't allow you to switch outa battery without taking it to a store or voiding yourwarranty.Depending on the manufacturer, a tablet computer maybe underpowered on purpose. Computer CPUs executecommands in clock cycles. The more clock cycles a CPU


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runs per second, the more instructions it can process. Some tablets haveunderclocked processors, meaning the CPU is set to run fewer instructions persecond than it's capable of executing. The reason for making a CPUunderperform on purpose is to reduce heat production and conserve batterylife.While you might be irritated to learn your new tablet isn't performing at fullspeed, the truth is most tablets don't need the extra processing power. Programsfor tablets tend to be less complex and robust than computer programs. Thecommon term for these programs is applications or apps.Besides the CPU and battery, other components you'll likely find in a typicaltablet include:

" accelerometers

" gyroscopes

" graphics processors

" flash-based memory

" WiFi and/or cellular chips and antennas

" USB dock and power supply

" speakers

" a touch-screen controller chip

" camera sensors, chips and lensesAccelerometers and gyroscopes help the tablet determine its orientation so thatit displays graphics in either portrait or landscape mode. The graphicsprocessor or GPU takes the load off of the CPU when it comes to generatinggraphics. The WiFi or cellular components let you connect your tablet to acomputer network. The tablet may also have a Bluetooth receiver, allowing itto interface with other Bluetooth devices. One thing you won't find in mosttablets is a fan -- there's just not enough space.

Touch Screens and Tablets

There are two basic methods of creating touch screens for tablet devices:resistive screens and capacitive screens. Manufacturers have to choose betweenthe two -- they don't work together.

Resistive systems detect a touch on a screen through pressure. Tablets thatrequire a stylus often use resistive screens. But how does it work?

Resistive systems have a layer of resistive material and another layer ofconductive material. Spacers hold the two layers apart. When the tablet is on,an electric current runs through both layers. If you put pressure on the screen,it causes the two layers to come into contact with one another. This changes

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the electrical field for those twolayers.

Imagine you own such a tabletand you've decided you wantto activate a game. You useyour stylus to tap the gameicon on your tablet's screen. Thepressure from your touch causesthe two layers in the resistivesystem to touch, changing theelectric field. A microchip insidethe tablet interprets this changein the field and translates it intocoordinates on the screen. Thetablet's CPU takes thesecoordinates and maps them

against its operating system. The CPU determines that you have activated theapp and launches it for you.

Resistive screens can be susceptible to damage. If you use too much pressure,you may cause the resistive and conductive layers to be in constant contact.This will cause the tablet to misinterpret commands. Resistive screens also tendto have poorer resolution than capacitive screens.

A capacitive system also detects changes in electrical fields but doesn't relyon pressure. A capacitive system includes a layer of material that stores anelectrical charge. When you touch a conductive material to this screen, someof that electrical charge transfers over to whatever is touching it. But thematerial must be conductive or the device won't register a touch. In other words,you can use anything to touch a resistive screen to register a charge but onlyconductive material will work on a capacitive system.

Capacitive systems tend to be more robust than resistive systems since youdon't have to press down as hard to register a touch. They also tend to havea higher resolution than resistive systems.

History of TabletsThe idea of the tablet computer isn't new. Back in 1968, a computer scientistnamed Alan Kay proposed that with advances in flat-panel display technology,user interfaces, miniaturization of computer components and some experimentalwork in WiFi technology, you could develop an all-in-one computing device.He developed the idea further, suggesting that such a device would be perfect

The Apple iPhone uses acapicitive touch-screeninterface, as do many tabletcomputers.


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as an educational tool for schoolchildren. In1972, he published a paper about the deviceand called it the Dynabook.The sketches of the Dynabook show a device verysimilar to the tablet computers we have today,with a couple of exceptions. The Dynabook hadboth a screen and a keyboard all on the sameplane. But Key's vision went even further. Hepredicted that with the right touch-screentechnology, you could do away with the physicalkeyboard and display a virtual keyboard in anyconfiguration on the screen itself.

Key was ahead of his time. It would take nearly four decades before a tabletsimilar to the one he imagined took the public by storm. But that doesn't meanthere were no tablet computers on the market between the Dynabook conceptand Apple's famed iPad.

One early tablet was the GRiDPad. First produced in 1989, the GRiDPadincluded a monochromatic capacitance touch screen and a wired stylus. Itweighed just under 5 pounds (2.26 kilograms). Compared to today's tablets,the GRiDPad was bulky and heavy, with a short battery life of only three hours.The man behind the GRiDPad was Jeff Hawkins, who later founded Palm.

Other pen-based tablet computers followed but none received much supportfrom the public. Apple first entered the tablet battlefield with the Newton, adevice that's received equal amounts of love and ridicule over the years. Muchof the criticism for the Newton focuses on its handwriting-recognition software.

It really wasn't until Steve Jobs revealed the first iPad to an eager crowd thattablet computers became a viable consumer product. Today, companies likeApple, Google, Microsoft and HP are trying to predict consumer needs whiledesigning the next generation of tablet devices. While it may have taken timeto hit the ground running, it seems likely we'll be seeing tablet computers onstore shelves for years to come.


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CMS COMPUTER INSTITUTE Installation of Windows VistaCMS COMPUTER

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28PC ENGINEERING

Installation of Windows Vista

Installing Windows Vista Client"Configuring Windows Vista Client," is aimed at information technology (IT)professionals who will be installing and supporting the Windows Vista clientoperating system. The first thing you should recognize is that the installationprocess is a critical task in a computer's life cycle. How you configure aWindows Vista client computer has significant ramifications for how it is usedthroughout its lifetime. Today, with more reliable hardware and software, fewpeople will need to have their operating system reinstalled from scratch. It islikely that the configuration decisions you make during the installation ofWindows Vista will remain in effect until the computer on which you install itis retired from service.As an IT pro, you are responsible for making configuration decisions for peoplewho have placed their trust in you. These people might be customers, workcolleagues, family members, or friends. These people have given you thisresponsibility because they lack your expertise and training. They need you todecide whether their current hardware is capable of running Windows Vista.Do you recommend that they upgrade components? Should they purchase anew computer entirely? Which edition of Windows Vista will best suit theirneeds? What sort of post-installation configuration of device drivers will benecessary? This chapter will help you address all of these questions and willstart you on your journey to better understanding the Windows Vista operatingsystem.

Exam objectives in this chapter:

• Identify hardware requirements.

• Perform a clean installation.

• Install and configure Windows Vista drivers.

Lesson 1: Identifying Hardware RequirementsThe objective of identifying hardware requirements can be boiled down to a

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CMS COMPUTER INSTITUTE Installation of Windows Vista

single question: "Will this computer run Windows Vista well?" Although it ispossible to install Windows Vista on a computer that does not measure upto the minimum requirements, the person's experience in using that computeris not going to be as agreeable as it might be. In some situations, hardwarethat does not meet the minimum requirements will mean that it is simplyimpossible to install Windows Vista at all. This lesson will help you determinewhether a particular hardware configuration is sufficient to run Windows Vista.This lesson will also provide you with an overview of each Windows Vistaedition.

After this lesson, you will be able to:

? Determine Windows Vista client hardware requirements.

? Differentiate each edition of Windows Vista based on its feature set.

? Understand the difference between Windows Vista Capable and WindowsVista Premium Ready specifications.

? Run the Upgrade Advisor.

Assessing Hardware RequirementsAt its simplest, assessing hardware requirements means comparing two listsof specifications. The first list of specifications is what you need to run WindowsVista. The second list of specifications shows the current state of the computeron which you want to run Windows Vista. The four primary hardware componentsthat you need to assess in determining whether you can install Windows Vistaare:

• Processor • RAM • Hard disk drive • Graphics adapter

ProcessorAlthough there are multiple processor architectures, Windows Vista requiresthat a processor have a minimum speed of 800 MHz. The recommendedprocessor speed is greater than 1 GHz. Windows Vista will function on both32-bit and 64-bit architectures. If you want to run Windows Vista on a 64-bitarchitecture, you should ensure that you obtain the 64-bit edition of WindowsVista rather than the standard 32-bit edition. The 64-bit edition of WindowsVista will provide improved performance on 64-bit hardware over the 32-bitedition.

RAMNot only do you need enough RAM to run the operating system, but you alsoneed extra RAM to run applications. Most people like to run several applicationsat once, such as a word processor, e-mail client, web browser, and chatprogram. When a computer begins running out of available RAM, it begins

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to use the page file. A page file is a special file, usually hidden, that is usedto hold parts of programs and data files that do not fit within the computer'sphysical memory. Data is moved from the paging file to memory and backagain as required. The page file is sometimes called the swap file. The morea computer uses the page file, the slower the computer gets. You can oftenimprove the speed of a computer more by increasing the amount of RAM ithas than you can by increasing its processor speed. Windows Vista has aminimum recommended RAM of 512 MB and a recommended RAM of 1 GB.

Hard Disk DriveHaving enough free space on the volume to install the operating system is onething, but you will need space for an office productivity suite, all that e-mailthat arrives, and space to install the latest and greatest games. Although astandard Windows Vista installation will consume approximately 7 GB of harddisk drive space, the recommended minimum amount of hard disk drive spaceis 20 GB, and the recommended amount is 40 GB. If you had only 7 GB ofhard disk drive space, you would not be able to install any extra applications!

Graphics CardWindows Vista has two graphics interfaces: the basic interface and the moreadvanced Windows Aero interface. Windows Aero is more aesthetically pleasing,but Windows Vista is still fully functional if using only the basic interface. Theminimum requirement to run the basic interface is a graphics adapter that isDirectX 9 capable. You can find information on whether a graphics adapteris DirectX 9 capable on the vendor's website or on the product packaging. Torun Windows Aero, a graphics adapter needs:

• DirectX 9 capacity

• A WDDM Driver

• Hardware Pixel Shader 2.0

• 32 bits per pixel

• A minimum of 128 MB graphics memory

Comparing Windows Vista EditionsTo the uninitiated, one of the most challenging things about Windows Vistais the number of editions it comes in. Each edition, or SKU (Stock Keeping Unit),is aimed at a particular target audience, and each edition has a particularprice point. It is likely that in your job as an IT pro, you will have to providerecommendations to friends, family, and customers about which edition ofWindows Vista will best suit their needs. To understand the differences betweeneditions, you should first know the meaning of several terms.

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• Active Directory Domain Active Directory directory service domains arerarely used in the home environment but are common in medium andlarge enterprises. Active Directory domains require a computer running aWindows server operating system.

• Aero The new Windows Vista graphical user interface (GUI), which is moreefficient and aesthetically pleasing than the Windows XP or Windows 2000interfaces.

• Media Center Allows a computer to play live and recorded standard andHDTV, movies, music, and pictures all through a single application.

• Full Hard Drive Encryption Enables a hard disk drive to be encrypted onthe volume level rather than at the individual file and folder level.

• Tablet PC capacity The ability to run on a Tablet PC and accept pen-basedinput from the screen.

• Multiprocessor support The ability to use more than one processor.

• Parental controls Allows parents to restrict the websites and games thattheir children's user accounts can access.

Windows Vista StarterWindows Vista Starter is the most basic version of Windows Vista. This editionsupports only a single 32-bit processor. Starter cannot be used in a domain,cannot run the Aero GUI, does not support Media Center or full hard driveencryption, and cannot be run on a Tablet PC. This edition allows only threeapplications to run simultaneously and does not support inbound networkconnections. This edition does not support parental controls. This affordableedition is primarily aimed at computer users in emerging markets.

Windows Vista Home BasicWindows Vista Home Basic differs from the starter edition in that it comes inboth 32-bit and 64-bit editions. Home Basic Edition cannot be used in adomain, cannot run the Aero GUI, does not support Media Center or full harddrive encryption, and cannot be run on a Tablet PC. Home Basic does supportparental controls and allows users to have more than three applications openat once.

Windows Vista Home PremiumLike Windows Vista Home Basic, Windows Vista Home Premium cannot beused in a domain. It does, however, support the Aero GUI, it can be run ona Tablet PC, and it supports Media Center functionality. Home Premiumsupports parental controls and allows users to have more than three applicationsopen at once.

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Windows Vista BusinessWindows Vista Business supports Aero and Tablet PC functionality. A WindowsVista business PC can also be a member of a domain. Windows Vista Businessdoes not support Media Center and does not support full hard disk driveencryption.

Windows Vista EnterpriseWindows Vista Enterprise supports Aero and Tablet PC functionality. A WindowsVista Enterprise computer can be a member of a domain and can use full harddisk drive encryption. Windows Vista Enterprise does not support Media Centerfunctionality. Windows Vista Enterprise is not available through regular retailchannels and is available only to organizations that have their computerscovered by Microsoft Software Assurance or a Microsoft Enterprise Agreement.

Windows Vista UltimateWindows Vista Ultimate supports all features of Windows Vista Enterprise andWindows Vista Premium. Computers running Windows Vista Ultimate can takefull advantage of Media Center functionality and can also be members of anActive Directory domain.

32-Bit and 64-Bit EditionsWindows Vista is available in both 32- and 64-bit editions. Although it ispossible to run a 32-bit edition of Windows Vista on a computer with a 64-bit processor, it is not possible to run a 64-bit edition of Windows Vista on acomputer with a 32-bit processor. The primary advantage of a 64-bit editionof Windows Vista is that it allows a computer to use significantly more RAMthan the 32-bit edition. The 64-bit editions of Windows Vista are generally usedfor specialized computing requirements, such as industrial design or computergenerated special effects.

Practice: Evaluating a Computer Prior to Installing WindowsVistaIn these practices, you will evaluate whether or not a computer is capable ofrunning Windows Vista. The first practice is an evaluation of the hardwarerequirements. The second practice involves running the Upgrade Advisor.Practice : Evaluate Computer Hardware Prior to InstallingWindows VistaThe Windows Vista Upgrade Advisor is limited in that it can run only on a subsetof the operating systems that are actually available. You might be considering,for example, running Windows Vista on a computer that has an operatingsystem such as Linux installed. In this case, you need to make your ownevaluation of the computer's hardware capacity.

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1. Review the minimum and recommended hardware requirements of WindowsVista.

2. Enter the computer's BIOS. When you power on a computer, it informs youwhich key to press to enter setup or BIOS.

3. Use BIOS to determine how much RAM is installed on the computer, asshown in Figure 28-1.

4. Use BIOS todetermine the sizeof the hard diskdrive installed inthe computer.

5. Use BIOS todetermine theprocessor speed ofthe computer.

6. Log on to thewebsite of themanufacturer ofyour computer'sgraphics adapter.Check whether the

graphics adapter meets the minimum or exceeds the recommendedspecifications for windows Vista.

Lesson 2: Installing Windows Vista

Although the installation process is straightforward, as an IT pro, you willneed to make several important decisions that will influence the configurationof the computer. This includes setting initial disk and volume configuration,security, and network discoverability options. Depending on the hardwareconfiguration of the computer on which you install Windows Vista, performingan installation can take some time. You need to understand the ramificationsof each decision. In some cases, if you choose the wrong option, the onlyremedy will to be to start over from the beginning. In this lesson, you willlearn about the Windows Vista installation process, a process that is likelyto become very familiar to you over the course of the next few years as anIT pro.

Performing the Windows Vista Installation

The first step in an average Windows Vista clean installation is inserting the

Fig. 28.1 Using BIOS todetermine the amount ofRAM a computer has


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installation DVD into thecomputer's DVD-ROM drive andallowing the computer to boot offthe DVD-ROM. Some computerswill not automatically boot fromthe DVD-ROM drive. This bypassis often implemented for securityreasons because it is possible toboot into an alternate operatingsystem if you can boot from theDVD-ROM drive. To change thecomputer boot order so that theDVD-ROM drive is checked first,you need to enter the computer'sBIOS. From here it is possible toconfigure the boot order.

The first screen in the installation process, shown in Figure-28.2 below, askswhich language you want to install, the time and currency format, and thekeyboard layout you want to use. These selections are important because tryingto install an operating system in a foreign language is a difficult skill to master!Keyboard layout is also important; even keyboards from other English-speaking countries might superficially seem to use the same layout as a U.S.keyboard, but some of the keys are in different positions. If you are installingWindows Vista for someone who needs access to multiple keyboard layouts,it is possible to add these alternative layouts once Windows Vista is installed.The user can then switch between them as necessary.

Fig. 28-2 Select language,time and currency format,and keyboard layout

The next step in the installation process is the Install Windows page. Clickingthe Install Now button begins the installation. You also have the option ofrepairing your computer. If you click What To Know Before Installing Windows,you are reminded to:

? Verify that your computer meets the minimum hardware requirements.

? Have your installation media ready. At this point, of course, the media isin the drive!

? Ensure that you have located your 25-character product key.

? Have determined what antivirus software you will install after installationcompletes. A link to Windows OneCare is provided in the Welcome screenafter you complete installation. OneCare is a fully featured subscription-based application available from Microsoft that you can use to protect


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against viruses and to ensure that your computer has appropriate securitysettings. You do not have to select OneCare as your antivirus or securitysolution, and many other vendors have released comparable products.

? Prepare a name for the computer that you will enter during installation.If you are installing in an Active Directory environment, you should alsoknow the name of the domain that you want to join the computer to.

? Ensure that your Internet connection is working.

Clicking Install Now begins the installation process. After a moment, you areasked to enter the 25-character product activation key in the text box shownin Figure 28-3 and to select whether or not you want to automatically activateWindows when the computer connects to the Internet. It is possible to useWindows Vista for 30 days before you need to activate it online or bytelephone. Until you are an expert at installing Windows Vista, you shouldensure that you are completely happy with the installation and configurationprior to performing activation. That way, if you find something problematic,you will be able to reinstall from scratch without having to worry about a prioractivation using your 25-character product key.

If you want to enter the product key later, you receive a dialog box asking ifyou are sure. After it is installed, Windows Vista reminds you each day untilthe grace period expires that you need to perform the activation process.

Windows Product ActivationWindows Product Activation (WPA) is the method Microsoft uses to ensure thatWindows Vista is installed on only a limited number of computers. You shouldrecord each unique key and the computer that it is tied to in a table or in adatabase in case you misplace the installation media. Several separate

identifiers are used in the WPA process:

? Hardware ID An identifier that is generatedusing information generated from a computer'shardware configuration

? Product ID A 25-character unique key suppliedwith the installation media

? Installation ID An identifier that Windows Vistacreates from the hardware ID and product ID

During the WPA process, the Product ID andHardware ID are sent to Microsoft. A single ProductID cannot be tied to more than one Hardware ID.If the activation check finds that the Product ID has


Fig. 28.3 Enter the product key

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not been activated and tied to a Hardware ID, both IDs are recorded and theinstallation is activated. If the activation check finds that the Product ID is tiedto a different hardware ID, the activation fails.

MORE INFO Windows Product ActivationFor more information on Windows Product Activation, consult the followingwebsite: http://www.microsoft.com/technet/windowsvista/library/plan/e35edd60-9784-491d-8c51-7affbb42df30.mspx?mfr=true

Microsoft allows you to reinstall and reactivate Windows Vista on the samecomputer once. Trying to do so again results in WPA failing, and you needto contact Microsoft support. If you substantially change your hardwareconfiguration, you also need to reactivate Windows Vista. Changing a singlecomponent does not force reactivation, but changing multiple components-for example, motherboard, network card, and graphics adapter-forcesreactivation. This is to guard against people installing multiple copies ofWindows Vista on different computers by swapping hard disk drives around.

NOTE Wait until your system settlesWe have found that until you have installed a new operating system a few times,you are likely to want to reinstall once or twice. With Windows Vista's hardwarerequirements, you will probably consider upgrading some of your hardwareafter you have installed to improve your experience. For this reason, werecommend that you do not go through the activation process until you arepositive you are happy with your current configuration. That way, if you findyou have to revise your hardware configuration, you do not have to worryabout activation problems.

Selecting an Edition of Windows VistaThe next stage in the installation process, shown in Figure 28.4, involvesselecting the edition of Windows Vista that you will install. The Windows Vistainstallation media ships with all editions of Windows Vista; however, you canactivate only the version of Windows Vista that you have purchased. Eachunique 25-character product key is tied to a specific edition of Windows Vista.If you install an edition that does not match your 25-character product key,you will either have to reinstall from scratch after the 30-day activation periodhas expired or purchase the edition that you have installed. If you purchasea new edition, you will receive a new unique 25-character product key.

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Fig.28.4 Select the editionof Windows Vista that youhave purchased

For example, if you install Windows Vista Ultimatebut have purchased Windows Vista Business orHome Basic, you will need to reinstall from scratchor purchase a license for Ultimate. There is anexception to this rule. If you purchase Ultimate butaccidentally install another edition, you will beable to perform an in-place upgrade to Ultimate.When you are sure, select the I Have Selected TheEdition Of Windows That I Purchased check box,and click Next.

Performing a Custom InstallationThe option to upgrade is presented only if you run the Windows Vistainstallation routine from an existing Windows XP or Windows Vista installation,and the computer meets the upgrade requirements. If you have booted off theWindows Vista installation media, only the Custom option is available.

The Where Do You Want To Install Windows page shows a list of all disks andpartitions available on the computer. From this page, you can load a driverfor a disk drive if one is not already included with Windows. This is oftennecessary only with special high performance disks or redundant array ofindependent disks (RAID) arrays. If your hard disk drive is not visible when youreach this part of the installation routine, you need to install the appropriatehard disk driver.

Clicking Drive Options (Advanced) brings up tools, shown in Figure 28.5, thatyou can use to create a new partition, format, extend a partition across multipledisks, or load a driver. It is not necessary to use the advanced drive optionsunless you want to create multipleseparate partitions. Extending volumes

across partitions and disks is beyond the scope of the 70-620 exam. Windows Vista automatically creates andformats a partition if you do not use any of the advancedoptions.

Generally speaking, you will want to allocate as muchspace as possible to the partition that will host the WindowsVista volume. By default, all applications are installedonto the volume that hosts Windows Vista. Most peopledo not delete applications that they have installed unless



Fig. 28.5 Drive options

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they have to, which means that over time, the amount of disk space used onthe volume that hosts Windows Vista fills. This is especially the case if the personthat you are building the computer for likes to play computer games. Moderngames take up many gigabytes of disk space. If someone installs a new gameeach month, that person might use more than 100 GB of storage capacity withina year! If you are ever asked to free up disk space on someone's computer,you should check whether the user has installed any games.There are also good reasons to partition disks. Windows Vista allows you tocreate mirrored volumes across separate disks as a way of protecting data.Although you will want to ensure that the volume that hosts Windows Vista hasas much space as possible, setting up a separate volume to host data, suchas Microsoft Office documents, simplifies setting up redundancy and alsogreatly simplifies configuring backups.

CAUTION Disks, partitions, and volumesThese three terms are sometimes used interchangeably in technicaldocumentation. This can be confusing for readers. A disk is the physical harddisk drive. A partition is a logical segmentation of a hard disk drive. A volumeis a formatted storage area contained within a partition. If you open WindowsExplorer, you are able to view only volumes. The only way that you can viewdisks and partitions is through the Disk Management tool, which is accessiblethrough the Computer Management console.

After these stages of the process are complete, the installation routine beginscopying files from the Windows Vista media to the newly created volume.Features are then installed. After these aspects are completed, the installationreboots.Your input is not required until the Windows Vista routine reaches the ChooseA User Name And Picture page. Here you are asked to enter a username anda password and to select a picture to represent your user account. You will needto enter the password twice and provide a password hint, as shown in Figure28-6. It is important for you to note that this account automatically becomesa member of the local administrators group. For this reason, you should makethe username and password memorable, though be careful to keep them bothsecured. Whoever has access to this username and password pair has completecontrol of this computer. For this reason, you should also ensure that the hintyou provide is not too obvious. Unlike previous versions of Windows, WindowsVista ships with a built-in Administrator account that is disabled by default.The next step is to enter a computer name. Windows Vista offers a name basedon the user-name you entered in the preceding step. You should select a name

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that is informative rather than wildly imaginative.Good computer names relate to the computer's role.Accounts01 is an excellent name for a Windows Vistacomputer used in a company's accounting department.

NOTE Label a computer clearlyAlthough it is not critical in the home, it is easy to losetrack of computer names if you work in a largeenvironment. In such an environment, you shouldlabel the exterior of a computer with its computername. That way it is easier to track the computerdown when you get a message in the server log that

something has gone wrong with a particular client computer.

The next stage of the installation process asks whether you want to installupdates. The options are as follows:

? Use Recommended Settings This installs important and recommendedupdates and helps make Internet browsing safer. It also contacts Microsoftto see if there are solutions to any problems you encounter, such as amissing hardware driver.

? Install Important Updates Only Download and install any importantsecurity updates Microsoft has issued since Windows Vista's release.

? Ask Me Later Do nothing at the moment. A warning is provided that thecomputer might be vulnerable to security threats.

Although it might seem obvious that using the recommended settings is thebest solution, there are good reasons why you might select Ask Me Later. Ifyou are installing 100 Windows Vista computers, you will not want each oneof them downloading a copy of the same files over your company's Internetconnection from the Windows Update servers. Windows Update is a freeservice through which Microsoft provides patches and updates to your software.It is possible to install Windows Server Update Services (WSUS), an additionalcomponent that runs on Windows Server software that allows an organizationto have a local Windows Update server. Each of the 100 Windows Vistacomputers would be able to retrieve all released updates over the company'slocal area network (LAN) rather than each of them downloading them fromthe Internet. If your organization is charged for the amount of traffic downloadedover its Internet link, implementing WSUS can bring significant cost benefits.The installation routine then asks you to review your time and date settings,


Fig. 28.6 Configguring ausername and password

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as shown in Figure 28.7. Be sure to set the correcttime zone and date for your computer. If yourregion shifts to daylight savings during the summermonths, ensure that the Automatically Adjust ClockFor Daylight Saving Time check box is selected.During installation you do not need to set WindowsVista's time more accurately than the closestminute. When the computer is connected to theInternet, it synchronizes with time servers that keeptime using an atomic clock. By default, once aweek all Windows Vista computers synchronizewith a time server located at time.windows.com.Many people use their home computers to tellthem the accurate time rather than calling thetelephone company's automated service.

After completing the configuration of the time and date,the installation process presents the Select Your Computer'sCurrent Location dialog box, as shown in Figure 28.8.Setting a computer's location determines how it interactswith the local network. Setting the network to Homeconfigures the network to attempt to discover peer-to-peer network devices. Setting the network to Workconfigures Windows Vista to attempt to discover domainresources. Configuring the network to Public Locationmeans that the computer will not interrogate other deviceson the network. In all cases, the Windows Firewall isactive. The settings in this dialog box determine how

inquisitive Windows Vista is about other devices on the local network.Microsoft recommends that if you are unsure of what to choose, you shouldselect Public Location. Making a selection here completes the installation.

Fig. 28.7 Setting yourcomputer's time zone

Fig. 28.8 Selecting acomputer's location

Quick Check

1. How long do you have after installation to activate Windows?

2. You have purchased Windows Vista Ultimate but have accidentally installedWindows Vista Home Premium. What step should you take to remedy theproblem?

Quick Check Answers

1. You have 30 days to activate Windows after installing it.

2. Perform an upgrade to Vista Ultimate.



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Dual BootingDual booting is the process by which you select an operating system to runduring boot. When a computer is configured to dual boot, each operatingsystem is installed on a separate volume. Those volumes can be separatepartitions on the same hard disk drive or separate partitions on separate harddisk drives. Although virtual machines are making dual booting less popular,there are several reasons to dual boot. These include:

? Your organization requires you to run either Windows 2000 or WindowsXP but has asked you to also test Windows Vista.

? You are a developer who wants to switch between multiple operatingsystems, such as Windows Server 2003 and Windows Vista.

? Your computer does not have enough memory to run different operatingsystems within virtual machines.

When configuring dual booting, you need to ensure that you install WindowsVista after you install Windows XP. If you have to rebuild a computer that dualboots and you install Windows Vista prior to XP, there might be problems withthe way that the boot menu functions.When you dual boot, you are presented with a text menu asking you whichoperating system you want to run. To select Windows XP, or any other operatingsystem released prior to Windows Vista, use the arrow keys to select EarlierVersion Of Windows, as shown in Figure 28.9. Selecting Earlier Version OfWindows automatically boots Windows XP. If you have multiple earlier operatingsystems, such as Windows XP and Windows Server 2003, selecting EarlierVersion Of Windows brings up the original boot loader. From there you canselect between earlier versions of Windows as you would have prior toinstalling Windows Vista. If you install a version of Windows released after

Windows Vista-for example, Windows LonghornServer-this is listed as an option on the WindowsVista boot menu.

Fig. 28.9 Choosing Windows XP by selecting Earlier Version OfWindows in the boot manager

It is possible to change which operating systemyou want to boot by default in the System Propertiesdialog box. To configure which operating systemto boot by default, perform the following steps.

1. Click Start.

2. Right-click Computer, and then click Properties.This opens the View Basic Information AboutYour Computer window.


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NOTE Alternative methodsIt is also possible to get to this window by opening System inControl Panel. You will find that there are many ways to accessimportant Windows Vista tools. There is no right way to do it;just find what works for you.

3. On the Tasks pane, click Advanced System Settings.

4. In the User Account Control dialog box, click Continue.

5. In the Advanced tab of System Properties, click the Settingsbutton in the Startup And Recovery area.

6. Use the Default Operating System drop-down list, shown inFigure 28.10 to select the default operating system forWindows startup.

Fig. 28.10 Configuring thedefault startup operatingsystem Practice: Installing Windows Vista Business

Select Practice 1 or 2, depending on whether you want to install Windows Vistaon a computer with or without an existing operating system. If you have a freshcomputer or are installing on a virtual machine, you should select Practice 1.If you want to configure Windows Vista in a dual boot configuration withWindows XP, Windows 2000, or Windows Server 2003, do Practice 2. Practice2 assumes that you have a fresh unpartitioned hard disk drive available.Practice 1: Installing Windows Vista Business on a Computer Without anOperating SystemIn this practice, you will install Windows Vista Business on a computer thatmeets the mini-mum hardware requirements outlined previously, "IdentifyingHardware Requirements." If you want to install Windows Vista to dual boot,you should do Practice 2 rather than Practice 1.

NOTE Windows Vista Virtual Server SettingsIf you are using Virtual Server 2005 R2, you should ensure that Virtual Server2005 R2 is upgraded to SP1. If configuring Windows Vista as a virtual machine,allocate a minimum of 512 MB of RAM to the virtual machine, although 1024is better. Allocate 25 GB of disk space to the virtual hard disk drive and ensurethat Undo Disks are enabled.

1. Ensure that the Windows Vista installation DVD is in the DVD-ROM driveand turn on the computer.

2. The Windows Vista installation routine should start automatically, and afterseveral moments you should see the language options screen. Set theoptions appropriate to your language, currency, and keyboard layout, andclick Next.


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3. On the Install Windows page, click Install Now. This begins the installationprocess.

4. The next screen is the WPA page. On this page, clear the AutomaticallyActivate Windows When I'm Online check box. You will perform WPA duringa practice in Chapter 3, "Troubleshooting Post-Installation System Settings."Click Next.

5. On the Do You Want To Enter Your Product Key Now page, click No.

6. In the Select The Edition Of Windows That You Purchased dialog box, clickWindows Vista Business, and then select the I Have Selected The EditionOf Windows That I Pur-chased check box.

7. Click Next. On the next page, review the Windows Vista license terms, andthen select the I Accept The License Terms check box. Click Next.

8. Because you are installing on a clean system, the Upgrade option isdisabled. Click Custom.

9. On the Where Do You Want To Install Windows page, ensure that the diskthat you want to install Windows on is selected. Click Drive Options(Advanced).

10.Click New to create a new partition on the allocated space. By default,a new partition is allocated all remaining space on the disk. Click Apply.This creates a new partition.

11.Click Format to create a volume on the newly created partition. A warning,shown in Fig-ure 1-13, informs you that all data stored on the partitionwill be deleted. Because the partition is newly created, there is no datato lose.

Fig. 28.11 Partition deletion warning


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12.Windows automatically formats the partition using the NTFS file system.When the installation routine has finished formatting the partition, clickNext.

13.You need to wait for some time while Windows copies files, installs featuresand updates, and then completes the installation. The installation rebootsduring this process.

14. In the Choose A User Name And Picture page, assign the username VikramPatel and the password P@ssw0rd. You need to enter the password twice,and you should enter a hint to remind you of what the password is. ClickNext.

NOTE Setting your own username and passwordThe practice items in this book assume that the initial username set up is VikramPatel and the assigned password P@ssw0rd. If you decide to use a separateusername and password pair, substitute it each time you see Vikram Patel.

15. In the Type A Computer Name dialog box, shown in Figure 28.12, type620-Vista. Select a desktop background, and then click Next.

Fig. 28.12 Selecting a computer name and desktopbackground

16.On the Help Protect Windows Automatically page, click Use RecommendedSettings.

17.On the Review Your Time And Date Settings page, select your time zone.If you live in a region that uses daylight savings time, ensure that theAutomatically Adjust Clock For Daylight Savings Time check box is selected.Ensure that the date is correct and that the time setting is accurate to withinseveral minutes of the current time. Click Next.

18.On the Select Your Computer's Current Locationpage, click Public Location.

19.Click Start to complete the installation. WindowsVista now checks the computer's per-formanceand assigns a rating before presenting you withthe logon screen.

? Practice 2: Installing Windows Vista Business in aDual Boot Configuration

In this practice, you will install Windows Vista on thesecond hard disk of a computer that already hasWindows XP installed. If you have performed thefirst Windows Vista installation practice, there is noneed to perform this practice.


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1. Ensure that the Windows Vista installation DVD is in the DVD-ROM drive.

NOTE Preparing for dual bootThis practice is offered for people who do not have enough RAM to run virtualmachines or who want to dual boot their current computer with Windows Vista.There are two basic ways of preparing an existing computer to dual boot. Thefirst is to install a second hard disk drive. The second is to purchase a diskrepartitioning tool. Given the licensing fees and the chance of losing data, werecommend that you purchase a second internal hard disk drive.Several software tools will reliably repartition a disk that currently holds data.The license fee for these tools is around the same cost as a new hard disk drivewith several hundred gigabytes of storage.

2. Turn on the computer. When you see the prompt:

Press any key to boot from CD or DVD

press the spacebar. This starts the Windows Vista installation routine.

3. After several moments, you should see the language options screen. Setthe options appropriate to your language, currency, and keyboard layout,and click Next.

4. On the Install Windows page, click Install Now. This begins the installationprocess.

5. The next screen is the activation page. Clear the Automatically ActivateWindows When I'm Online check box. You will perform product activationin Chapter 3, "Troubleshoot-ing Post-Installation System Settings." ClickNext.

6. In the Do You Want To Enter Your Product Key Now dialog box, click No.

7. In the Select The Edition Of Windows That You Purchased page, selectWindows Vista Business, and then select the I Have Selected The EditionOf Windows That I Purchased check box

8. Click Next, review the Windows Vista license terms, and then select the IAccept The License Terms check box. Click Next.

9. To upgrade to Windows Vista, you need to start the installation processfrom Windows XP rather than booting off the Windows Vista DVD-ROM.Click Custom.

10.On the Where You Do You Want To Install Windows page, click DriveOptions (Advanced).

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11. Locate the new drive that youhave just installed. In Figure28.13, you can see that the newlyinstalled drive is Disk 1. The entiredrive is unallocated, and it hasno partitions. Disk 0, on the otherhand, has a single partition of5.0 GB and a small amount ofunallocated space.

Fig. 28.13 InstallingWindows Vista on asecond disk

12.Ensure that the disk withunallocated space is selected,and click New.

13.By default, all space on the diskis allocated to the new partitionon which you install WindowsVista. Click Apply.

14.Click Format to format the newly created partition with the NTFS file system.When the installation routine has finished formatting the partition, clickNext.

15.You need to wait for some time while Windows copies files, installs featuresand updates, and then completes the installation. The installation rebootsduring this process.

16.At the Choose A User Name And Picture page, assign the username VikramPatel and the password: P@ssw0rd. You need to enter the password twice,and you should enter a hint to remind you of what the password is. ClickNext.

NOTE Setting your own username and passwordThe practice items in this book assume that the initial username set up is VikramPatel and the assigned password is P@ssw0rd. If you decide to use a separateusername and password pair, substitute it each time you see Vikram Patel.

17. In the Type A Computer Name dialog box, shown earlier in Figure 28.12,type 620-Vista. Select a desktop background, and then click Next.

18.On the Help Protect Windows Automatically page, click Use RecommendedSettings.

19.On the Review Your Time And Date Settings page, select your time zone.If you live in a region that uses daylight savings time, ensure that theAutomatically Adjust Clock For Daylight Savings Time check box is selected.Ensure that the date is correct and that the Time setting is accurate to within


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several minutes of the current time. Click Next.

20.On the Select Your Computer's Current Location page, click Public Location.

21.Click Start to complete the installation. Windows Vista now checks thecomputer's per-formance and assigns a rating before presenting you withthe logon screen.

Lesson Summary? If a computer does not boot directly into the Windows Vista installation

routine, you might need to alter the BIOS settings.? Prior to installation, you should ensure that you have your 25-character

product key, have determined what antivirus solution you will implement,have chosen a computer name, and have chosen a user account nameand password for the computer.

? Windows Vista allows you a 30-day activation grace period after thecompletion of the installation process.

? The unique 25-character product key ties you to a specific edition ofWindows Vista. If you install an SKU of Windows Vista higher than the oneyou purchased, you will have to purchase the higher version or reinstallfrom scratch.

? If the disk that you want to install Windows Vista on is not visible duringthe installation process, you will have to install the correct driver.

? The user account that you create during the installation process will be thedefault administrator account for the Windows Vista computer. The defaultbuilt-in administrator account is disabled in Windows Vista.

? Unless you have a special network configuration, you should use therecommended settings when Windows Vista asks whether you want todownload and install updates.

? If you are unsure of which location to specify when the Windows Vistainstallation routine asks you, select Public Location.

? When a computer is configured to dual boot, each operating system isinstalled on a separate volume.

LAB EXERCISE 28.1 : Windows Vista Installation

Objective : To be familiar with the different installation types as installing the OS.

Tasks:1. Install the Windows 98SE OS and observe the different switches with setup

program and try some of the switches.

2. If possible, try out the different installation types i.e. difference between typicaland custom etc.

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CMS COMPUTER INSTITUTE Managing Application on Windows VistaCMS COMPUTER

INSTITUTE

29PC ENGINEERING

Managing Applicationon Windows Vista

Introduction Adding software is usually done with the installation disk or executable, whileadding Windows components can be done within the "Add and RemovePrograms" utility. In order to change or remove a program in Windows Vista,you must either use the "uninstall" utility bundled with the program you wishto remove, or more often, use the "Program and Features" option in theWindows Vista control panel (with the advent of Windows Vista, the WindowsXP "Add and Remove Programs" utility was renamed to "Programs and Features").DO NOT delete folders under your C: drive in an attempt to remove anunwanted program-this can cause serious problems with your operatingsystem, often leading to full operating system reinstalls. The following instructionsapply to all versions of Vista.

How to Remove Programs

1. Click on the "Start" button, located in the lower left corner of your screen.

2. Click on "Control Panel" to access control panel options.

3. The system may warn you that changing these options may negativelyaffect your system. Ignore this warning and proceed.

4. Click on Programs, then Programs and Features.

5. Select the program you wish to change or uninstall. To uninstall, clickuninstall and follow the directions. To change or repair a program, clickon change or repair.

6. It is possible that you'll receive no further notification of the action fromWindows, or it may start a third-party program to assist with removaldeveloped by the software manufacturer.

Things to Remember:

" You may be prompted for an administrative password or some kind ofconfirmation-just enter it and proceed.

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CMS COMPUTER INSTITUTE Managing Application on Windows Vista

" If you can't find the program, it may have been made for an earlier versionof Windows, and you'll need to check the software's documentation.

How to Add/Remove Windows Components In order to add or remove Windows components, you must be an administratoron your computer.

1. Click on the "Start" button, located in the lower left corner of your screen.

2. Click on "Control Panel" to access control panel options.

3. The system may warn you that changing these options may negativelyaffect your system. Ignore this warning and proceed.

4. Click on Programs, then Programs and Features.

5. Click Turn Windows Features on or off, located on the left side of the screen.

6. Follow the instructions in the Windows Features Wizard.

Things to Remember:

" If an item is checked in the Windows Features Wizard, it's already installed.

" If you installed Windows components but did not configure them atinstallation, there will be a list. Click configure and follow the instructions.


Fig 29.1 Remove programs

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Installing Office 2007in Windows VistaMicrosoft Office 2007software is developed byMicrosoft for Windows andother operating systems. Itsmain applications areWord, Excel, Outlook,PowerPoint and Access. It ismost popular suite as it hasbeen the most widely usedsince its versions forWindows 1.0 which waslaunched in 1990.If you want to installMicrosoft Office 2007 onyour system then followthese guidelines:STEP 1. Insert the Office2007 Installation CD intoyour computer's CD drive.It will take few seconds tostart the installat ionprocess. If the installationdoes not start automatically,open 'My Computer', thenopen the "OFFICE12 CD",and double-click the"SETUP.EXE".Microsoft Office WizardA 2007 Microsoft OfficeWizard window will appear(Figure 29.3); allow it toprocess. This procedure willprepare the necessary filesto start installing MicrosoftOffice 2007 on yourcomputer.



Fig 29.2 Add/Remove Windows Components

Fig 29.3

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STEP 2. The ProductKeyNow the setup will promptfor the Office 2007product key. Type theproduct key in the keyfield. Enter five charactersper field in box, and makesure that there are a totalof 25 characters. Afterentering the completeproduct key, cl ick 'Continue ' (Figure 29.2).If you are unable to findthe product key on the CDthen click on the Windowshelp icon on the productkey page to open theMicrosoft help topic page

STEP 3. SoftwareLicense AgreementThe next screen shows theEnd-User LicenseAgreement (EULA). Nowclick the checkbox at thebottom corresponding to"I accept the terms in theLicense Agreement".Without accepting theEULA, the setup will notproceed further, so, it isrecommended that yougo through this once.Then click ' Continue '.(Figure 29.5).



Fig 29.4

Fig 29.5

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Step 4: ChoosingInstallation TypeThe next window shows theinstallation options for MSOffice 2007. If you want toinstall default applicationthat MS Office provides,click the selection button'Install Now'. This will startthe installation process.The other installat ionoptions is Custom Install:Custom Install: Here'swhere you'll find maximumconfigurability. If you havea good idea of how you'llbe using Office and itsindividual applications,this selection will let youtailor the installation moretightly to your specificneeds. (see Figure 29.6).

Step 5: InstallationOptionsThe Installation Optionstab now appears (Figure29.7). Left-click on the rootdirectory called MicrosoftOffice. On the drop-downmenu select Run all fromMy Computer and click onInstall Now.



Fig 29.6

Fig 29.7

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Step 6: File LocationNext, click on the FileLocation tab. Make sure thatthe installation directoryreads C:\ProgramFiles\Microsoft Office (Figure29.8). If you do not want totype this address, you cansimply click the Browse…button and select thelocation where you wish toinstall Microsoft Office2007.

Step 7: User InformationFinally, click on the UserInformation tab (Figure 29.9).In the Full Name, Initials, andOrganization fields fill in yourname, your initials, and TrinityUniversity, respectively. Afterthis information has beentyped click on Install Now tocontinue.Once you're done selectingwhat type of install to do, tobegin installation, click on the'Install Now' button and thiswil l start the process ofinstalling Microsoft Office2007 on your computer. Afterstarting the installat ionprocess, a progress bar willbe displayed showing that



Fig 29.8

Fig 29.9

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Microsoft Office 2007 is currentlybeing installed on your computer.After a few minutes, MS Office2007 will be completelyinstalled on your system andnow you can enjoy working withOffice 2007.

Step 8: InstallationProgressThe Installation Progress windowwill now appear (Figure 29.10).

Step 9: Office OnlineClick on the Go to Office Onlinebutton (Figure 29.11). An InternetExplorer window will open.Follow the on-screen directionsin order to update your MicrosoftOffice software and protectyourself from possible securityvulnerabilities.

Step 10: FinishedCongratulations, yourinstallation and updating ofMicrosoft Office 2007 is nowfinished. Be sure to check fornew updates on a monthly basisvia Office Online to protect yourcomputer from securityvulnerabilities. To access yournew software click on the Startbutton, move to All Programs,Microsoft Office and select theMicrosoft Office product you wishto use.



Fig 29.10

Fig 29.11

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.

LAB EXERCISE 29.1 : Installing Different Application in Windows Vista

Objective: To be familiar with the installation as well as use of the different applica-tions which are commonly used in Windows 98.

Tasks:1. Install one of the in-built utilities such as "Backup" which is present along with

Windows 98 OS.2. Try installing Office 2000 and utilize one of the Office programs such as Word to

create your Resume.3. Now try installing WinZip and verify whether there is any difference by using

WinZip.4. In the Outlook Express, try creating an account, create a mail and send it and

then verify by using a POP3 account or Hotmail account, whether it is actuallyworking i.e. whether one is able to send and receive mails.

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CMS COMPUTER INSTITUTE PC Assembling

Since we've covered the nitty-grittys of the functioning of each of the systemcomponents, it's time to get our hands dirty and actually put together an entiresystem.

Now we're not just talking of any system. Starting with the choice of theindividual components to the loading of the final operating system, we willbe stepping through the entire process of selecting, assembling, configuringand finally tweaking the system so that at the end of it all we have a seriouslypowerful and efficient powerhouse.

The basic principles underlying the assembly and the overall construction ofthe system remain constant, no matter which system you finally decide to build- be it an Internet surfing station to a trailblazing 3D gaming workstation.

Getting it all togetherFirstly, depending upon your budget, plan the purchase of each of the systemcomponents. Given the sheer variety of components available, this could bethe most tiring task while building the computer system. However, here is arule-of-thumb guide in choosing the components.

Each of the system components should be given a "weightage" of importancebefore buying components for the base system (that is, the system excludingperipherals like a printer, scanner etc). Generally, the following is the sequenceof importance that you could consider while deciding on your choice ofcomponents from the most to the least important: monitor, processor, RAM,hard disk, 3D graphics card, motherboard, sound card, CD/DVD drive,speakers, modem, casing, keyboard, mouse, floppy drive etc.

You might change the order of this list depending upon your specific applicationsand allot a greater importance of some components over others. For example,if you need a powerful system for 3D gaming, your 3D graphics card wouldhave greater importance than the choice of hard disk. The reason that greatimportance be given to the monitor is because it is the only component in yoursystem that can never really be "upgraded". While other components like the

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processor, RAM, 3D graphics card etc can be upgraded, your monitor willgenerally see your computer through its entire period of existence. Therefore,one must go in for the best monitor that one can afford and then settle uponother system components.

The following steps give as overview of assembling a computer.

1. Gather all your parts.

2. Open the case and remove the power supply and drive chassis.

3. Set up your motherboard.

• Install the CPU.

• Install main memory.

Tip: It's a good idea to connect everything you can outside the case firstand test each component as you install it. Only when you're sure everythingworks should you disassemble the test setup and install everything insidethe case. (That's why, even though you're putting everything together here,the last step is to "put it all together"). This approach makes troubleshootingmuch easier.

4. Install the video card (if the motherboard doesn't have integrated video)and test it.

5. Install the hard drive(s) and floppy drive.

6. Configure the BIOS.

7. Install your CD-ROM or DVD drive.

8. Install the operating system.

9. Install the sound card (if the motherboard doesn't have integrated audio).

10. Install your other expansion boards, such as internal modem and DVDdecoder board.

11. Put it all together:

• Install the motherboard.

• Install the power supply.

• Attach the add-on boards.

• Conduct another system check.

• Install the rest of the boards.

• Install the parallel and serial port connectors.

• Connect the front panel lights and speaker.Having collected all the components for the system, one can now get downto actually assembling the computer together.

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Step 1Open the system casing

Step 2Remove the backplate of the casing for mounting the motherboard



Step 3Align the motherboard with the mounting screws provided and see that the


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motherboard is fastened at all four corners and at least two places within themotherboard. This will keep the motherboard stable and provide a goodfoundation for the rest of the system's cards.Caution : Beware of static electricity as this can destroy a motherboard andrender it completely useless. To ensure that you are free from any static charge,the best approach is to wear a wrist-strap. This is a device that attaches to yourwrist with the other end attached to a grounded object like a metal pipe. Ifyou can't obtain a wrist strap, it is safest to refrain from wearing any shoes whilehandling the motherboard. This will discharge any static charge you might becarrying. In any case, handle the motherboard by its edges only.Do not completely tighten the screws after you affix the motherboard to thebackplate. Instead, lightly attach the board to the backplate with the help ofthe screws and spacers and tighten these screws only after you mount the cardson the board. This will prevent any unwanted stresses from being built up withinthe system (this is seen when you have to force cards into the slots aftermounting the motherboard). If the motherboard is initially mounted loosely,the cards will easily slide into the slots, as the board will have a little "play"in it. Only after you mount all the cards you should tighten the screws that fastenthe motherboard. The same rule should be applied while attaching themotherboard backplate to the casing-tighten the screws only after mountingthe cards.Also, before mounting the motherboard, you can use the foam that is usedto wrap the board as a backing for it so that the contacts on the undersideof the motherboard do not accidentally touch the backplate. Cut out the foamto the size of the motherboard and mount the board with the foam betweenthe board and the backplate. If there is no foam available, you could alsouse sheets of an old newspaper.

Step 4Mount the processor on the motherboard© CMS INSTITUTE 2005

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Remember to check any jumpers that you may have to set to configure themotherboard to the processor you have. These settings are indicated in themanual that accompanies the motherboard.

Caution : Remember to attach the connector for the CPU fan to the appropriatepoint on the motherboard. Failing to do so would result in your processoroverheating and could even result in permanent damage.

Step 5Mount the RAMThe RAM goes into the slots in only one direction so remember to align thenotches on the RAM to those on the slot.



Step 6Mount the motherboard and backplate in the system casing.

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Step 7Mount the CD/DVD drive© CMS INSTITUTE 2005

Step 8Mount the hard disk drive© CMS INSTITUTE 2005


Step 9Mount the floppy drive

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Step 10Connect the power cables to the motherboardIf you have an ATX power supply, the connectors will only fit into the motherboardin one direction. Align the connector so that the clip on the connector fits intothe one on the power connector on the motherboard socket.© CMS INSTITUTE 2005

Step 11Attach the front panel connectors to the motherboard© CMS INSTITUTE 2005

The indications for attaching the front panel connectors to the motherboardare shown in the motherboard manual.

Step 12Connect the primary IDE channel to the hard diskThe master IDE channel is indicated on the motherboard. Look out for anindication that reads "Pri. Master" or "IDE 0" on the motherboard.

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Step 13Attach the power connector to the hard disk.

Step 14Connect the secondary IDE channel to the CD/DVD driveBy connecting the CD/DVD drive to a separate IDE channel as a master drive,the efficiency of accessing the IDE devices will be much higher than connectingthe CD/DVD drive as a slave to the same channel as the hard disk.© CMS INSTITUTE 2005

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Step 15Attach the power connector to the CD/DVD drive© CMS INSTITUTE 2005

Step 16Connect the floppy drive to the motherboard connector.© CMS INSTITUTE 2005

Step 17Attach the power connector to the floppy diskAfter connecting the IDE and the floppy drives, now would be a good time toget hold a of a few rubber bands or tie-wraps and arrange the floppy, CDand hard disk cables. Group them together and tuck them out of the way ofthe airflow to the processor. This will eventually help your system to run cooler.

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Step 18Connect the serial, parallel and game ports to the motherboardIf you have a baby AT cabinet, you will need to attach these ports to themotherboard by way of the connectors that are supplied. Indications for doingso are outlined in the motherboard manual. This is not necessary for an ATXmotherboard as these ports are built onto the motherboard itself.After attaching these connectors, remember to group the cables together witha couple of rubber bands so that they do not obstruct the CPU fan or airflow.

Step 19Connect the display card


Caution : Remember to handle the card by its edges so as to prevent damagedue to static charge.Insert the card by first aligning the connectors to the socket on the motherboard.Then slide in the card by gently rocking it back and forth so as to ease it intothe slot. Do not try to force the card into the slot. See that the card is firmlyseated in the slot before fastening the screw.

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Step 20Mount the sound cardThis is necessary only if you are using a motherboard that does not have anyintegrated sound card.


Step 21Connect the audio cable from the CD/DVD drive to the sound cardConnect the "Audio out" socket from the CD/DVD drive to the "CD-In" connectoras indicated on your sound card.© CMS INSTITUTE 2005


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Step 22Connect the keyboard to the connector on the motherboard.© CMS INSTITUTE 2005

Step 23Connect the mouse to the port on the motherboardDepending upon which mouse you have, you should connect the mouse toeither the serial port or to the PS/2 port on your motherboard. Remember thata PS/2 mouse should always be connected to the outer PS/2 port on themotherboard while the keyboard is connected to the inner PS/2 port.


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Step 24Connect the VGA connector from the monitor to the display card


Step 25Connect the power cord to the power supply


Caution : Remember to verify that the power point that you are connectingyour computer to is properly earthed. Get this checked by an electrician sothat the delicate electronics in your computer are protected from stray voltagesthat may exist on the power lines.Step 26Connect the monitor's power cord to the monitor

Depending upon the type of power supply your cabinet has, the monitor'spower cord could be either connected to the mains power supply or to aconnector on the SMPS near the main power connector of the computer.

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Step 27Check all connections and cards

You are now nearly ready to power up your system. Before doing so, now'sa good time to check all the connections and cards in your system. Glanceover all the connectors to the drives and cards and see that they are securelyattached with no loose contacts anywhere.

Step 28Switch on the power to the system.Probably the most apprehensive part of building the computer, now's the timeto power up the system. Switch on the mains power and hit the power buttonon the casing. You should hear the hard disk spinning up and the motherboardshould emit a single "beep" signalling that all systems are functional. See thatthe CPU fan and the power supply is running.

Keep an eye out for any signs of instability in the form of the system hangingas this could mean that a setting on the motherboard could be incorrectly setor one of the cards might be loose, Observe the display and verify that theCPU speed indicated on boot-up is the rated CPU speed. If it isn't, shut downthe system and re-check the motherboard jumper settings for your CPU. In mostnew motherboards, these settings will have to be done from the CMOS. Hit"Del" when you see the message at the bottom of the screen to access the systemBIOS of the system.

Step 29Configuring the BIOS

One of the most effective methods to sap that extra power from your computerand enable it to run at full throttle is to tweak the BIOS. By changing parametersin the BIOS, the system could behave in a variety of ways. The system couldrun very smoothly, or it could run erratically or could stop functioning altogether.However, by adopting a systematic approach, a significant amount of powercan be extracted from your system by changing select parameters in yoursystem BIOS.

Step 30Close the system casingNow that your system is up and running and all the components are foundto be running well, the system casing can be closed. Fasten the four or six screwsat the back of the casing securely.

With all the hardware properly set up, you are now ready to load the operatingsystem. Load the operating system and verify that the system is functioningcorrectly and only then connect peripherals like the printer and scanner etc.

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Finally, for sapping that extra power out of your computer, it is recommendedthat you apply the tweaks to maintain the system. There are many utilities thathelp you to access registry settings and other parameters of your hard diskand operating system that can increase the overall speed of your system.

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CMS COMPUTER INSTITUTE Troubleshooting

The average PC has about a bazillion screen savers, application, backgroundcommunications programs (such as fax receive programs), and of course driverprograms for sound boards, network cards, video boards, and the mouse, toname just a few. Determining the source of a problem is really hard when thereare innumerable interactions between hardware and software.

The smart troubleshooter makes the troubleshooting job traceable by breakingdown problems into individual steps. Don't panic, and remember to bemethodical; otherwise, you will thrash helplessly about and get frustrated.Once you are frustrated, you are lost, and you start creating new problems.

The key steps you should take in troubleshooting most PC problems (whileremembering to stay calm and positive). Several of these steps occur beforeyou ever power down and remove the case.

1. Check for operator error-commands or configurations that you may havedone wrong, software or hardware that you may have set up incorrectly,or instructions that you may have reversed (for eg., literally reversing acable or putting a jumper on exactly opposite from the way it needs togo).

2. Check to make certain that everything that should be plugged into eithera direct power source or the PC itself is plugged in correctly, and that theconnection is secure.

3. Check the software, including program files and drivers, to make sure youhave the most current versions installed - and configured properly.

4. Check for external signs of trouble, such as flickering LED power indicatorsor those that don't come on at all, strange sounds or lack of sound, andlack of display.

5. Run appropriate diagnostic programs, which will be present in OS or someother 3rd party utilities.

6. Only when all else fail, disassemble the PC, shut it down, disconnect allpower, remove the case, ground yourself, and go inside to check cable and

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power connections, the proper seating of expansion boards and memorymodules, and anything out of the ordinary.

Diagnostics SoftwareSeveral types of diagnostic software are available for PCs. Some diagnosticfunctions are integrated into the PC hardware or into peripheral devices, suchas expansion cards, whereas others take the form of operating system utilitiesor separate software products. This software, some of which is included withthe system when purchased, assists users in identifying many problems that canoccur with a computer's components. In many cases, these programs can domost of the work in determining which PC component is defective ormalfunctioning.

All versions of Windows from Windows 98 on include a set of diagnostic systemtools (accessed via Start > Programs > Accessories > System Tools) that canhelp you track down many types of system problems. For eg., ScanDisk enablesyou to perform either a surface or thorough scan of your drives and tries tofix errors it finds; Disk Defragmenter defragments and reorganizes your harddrive to make it run more efficiently.

Microsoft's System Information tool provides a host of indispensable dataabout various components of your system, and (is its Tools menu) serves asa gateway for several more "hidden" utilities. These utilities include the Dr.Watson logging tool, which keeps track of operations performed and errormessages generated; System File checker, which seeks out missing or damagedessential files and attempts to replace them; and the System Information Utility(a.k.a. MSCONFIG), which enables you to set up a troubleshooting bootupmode and select which items you really want to load at Windows startup.

These diagnostics are not available directly within Windows 95 or WindowsNT 4. Windows 95 (as well as all later versions) does include Device Manager,one of the tabs available under the System icon in Control Panel. Althoughit's not a diagnostic checker, vital information gets reported there that you needto check when you're having a problem. You may see an exclamation markor red x on a device, indicating a device in conflict or disabled entirely. Oryou may find a needed device driver not present at all when it should be. Oryou may find a note on your hard drive indicating that the drive is runningin MS-DOS compatibility mode (meaning Windows feels the drive isn't set torun properly in Windows, so it's running in a slower mode compatible with MS-DOS).

Common Problems - and SolutionsSome of the more common hardware-related problems are as given belowand the possible ways to get over it as well.

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Your Computer Won't StartThis is perhaps the scariest problem you can encounter. Either nothing at allhappens, or you hear a few familiar or unfamiliar sounds, or even see ablinking light or two, but it all leads to a big fat zero. What can cause yourentire system not to work? Here are some things to look for:

• Make sure the power cable is connected, both to your PC and to eithera power strip/surge suppressor or wall outlet. If the cable is connected toa power strip/surge suppressor, make sure the strip is turned on-and thatother device plugged into the strip are working. (The strip itself could bebad). Make sure that the wall outlet has power.

• Check to see whether the power cable itself is bad. If you have a sparecable or one from another PC, try swapping it for the current cable.

• If your system unit lights up and makes noise but nothing appears on-screen, make sure that the computer monitor is turned on and gettingpower, and that it is connected properly and securely to the monitor outputon your system unit. If you suspect you actually have a monitor problemrather than a system unit problem, try connecting your PC to a differentmonitor.

• If your computer starts up but you receive an error message telling you thatyou have a non-bootable or invalid or non-system disk, you've accidentallyleft a floppy in drive A. Remove it.

• If your system tries to start but then locks up, it's possible you have sometype of damage to your main hard disk. You could have a damaged bootsector, or an internal connection may have worked loose, or your key systemfiles might have become corrupted. Try restarting with an emergency bootdisk (or the Windows Startup disk) and then use Scan Disk to check for harddisk errors.

• If your system appears to start but then generates a series of beeps (withnothing showing on your video display), it's possible that you have aproblem with your video card. (Consider this a probability if you've justinstalled a new video card)! Make sure the video card is seated firmly inits slot, you've switched the appropriate switches on your motherboard (ifnecessary) to recognize the new card. Try uninstalling the new card andreinstalling your old one it's possible the new card is defective.

• A beeping-and-not-starting scenario can also be caused by incorrectsettings in your system's CMOS setup. Check the video and memorysettings, specifically. Another possible cause is a bad memory chip or faultymemory installation. A weak or dead CMOS battery can also cause thisproblem.

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• If nothing turns on - no power lights light, no disk drivers whirr, nothing-it's possible that the power supply transformer in your system unit is bad.

Your Computer Locks UpIn terms of causing extreme user panic, a frozen system is second only to acompletely dead system. What can cause your system to freeze up? Here aresome of the most likely causes:

• It's possible that it's not your entire system that's locked up-it could be yourkeyboard or mouse. Check the connections for both these devices, andmake sure both cables are firmly plugged into the appropriate ports. Ifyou're using a wireless keyboard or mouse, replace your batteries.

• Misbehaving software problems are, perhaps, the greatest cause of frozensystems. If a program is stalled, try switching to another open program,either from the Windows Taskbar or by pressing Alt+Tab to shuttle throughall open programs. If things are still frozen, press Ctrl+Alt+Del (the old"three-fingered salute)" to display the Close Program dialog box; highlightthe program that isn't responding and click the End Task button. If, aftertrying all these actions, your system is still frozen, you'll have to rebootcompletely-press Ctrl+Alt+Del twice to shut down and then restart yourentire system. If even this doesn't shut things down, you'll have to use thePower button on your system unit - or, in the worst of all possible cases,unplug the system unit from its power source.

• Many computer lockups are caused by too many programs trying to usemore memory than is available. It's possible that you'll get a kind ofwarning before a total lockup; if your computer starts to slow down in themiddle of an operating session, it's a sure sign of an upcoming memory-related failure. If the problem recurs, try closing a program or two to freeup system memory-or upgrade the amount of memory in your system unit.

• Since Windows uses free hard disk space to augment random accessmemory, too little disk space can also cause your system to slow down orfreeze. Make sure you've gone through your folders and deleted anynonessential or unused files-especially TMP files in the \WINDOWS\TEMPdirectory.

Finally, any time something weird happens with your system, consider whetherthe problem could have been caused by a computer virus. Make sure you'rerunning some sort of antivirus program system sweep if you start experiencingperformance problems.

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A New Piece of Hardware won't Work - or Messes up yourSystemIt happens to the best of us. You install a new card or external peripheral, andall of a sudden your system either starts working funny or stops workingcompletely. Obviously, something in the new installation caused the problem- but what?

• Make sure that the new hardware is properly installed. If you installed anew internal board, make sure the board is fitted properly in its slot, thatany additional wires or cables are connected properly, and that anyswitches are set appropriately. If you installed a new external peripheral,make sure that its' plugged into the right port, that the cable is firmlyconnected, and that the device is hooked up to and is receiving externalpower (if that's required).

• Some new devices require you to rest specific jumpers or switches on yoursystem's motherboard. Check the item's installation instructions and makesure you've performed this vital step.

• Check your system configuration. It's possible that Windows Plug and Playdidn't recognize your new device, or didn't recognize it properly, or installedthe wrong driver. Try uninstalling both the hardware and its associatedsoftware, and then reinstalling. Use the Add new Hardware Wizard tooverride the standard Plug-and-Play operation.

• Make sure you have the latest version of the item's device drivers. Go tothe vendor's web site and download updated drivers, if necessary. (Whileyou're there, check the online support facilities to see whether any documentedproblems exist between this peripheral and your specific system).

• Look for an interrupt conflict, which could occur if the new device tries touse the same IRQ as an older device. This happens a lot with COM ports- not only is sharing the same port a problem, but some devices (such asmice and modems) don't like to share even- or odd- numbered ports. (Thismeans that you may have a conflict between COM1 and COM3 that couldbe fixed by moving one of the devices to COM2 or COM4). If worse comesto worst, try reassigning the IRQ for your new piece of hardware.

• It's possible that your system's CMOS settings need to be changed. This ismost common when you upgrade or change memory or disk drives. Enterthe CMOS configuration utility on system startup and change the settingsappropriate to the new hardware you added.

Your Hard Disk CrashesAny problem you may encounter with your hard disk is a major problem. That'sbecause everything from your system files to your program files to your data

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files resides on your hard disk.

What are the most common causes of hard disk problems? Here are a fewto look for:

• If your system can't access your hard disk at all, you'll need to reboot usinga system disk or the Windows Startup disk. Run ScanDisk (it's built into theWindows Startup disk) or a third-party hard disk utility from a floppy tocheck drive C for defects, and then fix any found damage.

• If the hard disk utility doesn't get your hard disk spinning again, it may bepossible to "rescue" the data on the damaged hard drive and transfer itto another disk.

• If you encounter frequent disk write errors, it's possible that you have somephysical damage on your hard disk. Run the hard disk utility to check andfix any defects.

• If your disk is working but running slower than normal it probably needsto be defragmented. Run a good disk defrag program (such as Windows'Disk Defragmenter) to get all those noncontiguous clusters lined up properly.

• If you experience a lot of disk write errors or your system runs much slowerthan normal, and if you're using DriveSpace for disk compression, theproblem is probably in DriveSpace. DriveSpace gives your system a prettygood workout and can cause lots of different types of problems. You mayfind that disk compression is more trouble than it's worth; if so, uncompressthe drive! (In these days of cheap hard drives, you're probably better offto install a second hard disk drive than you are to use DriveSpace or somesimilar disk compression utility).

Your Monitor Doesn't Display ProperlyIf your computer is working but your monitor isn't, look for the possible causes:

• Make sure the monitor is plugged in, turned on, and firmly connected toyour PC.

• Try to determine whether it's monitor problem or a video card problem.If you have a spare one handy, plug a different monitor into your PC; ifit works, your old monitor has a problem. If it doesn't, the problem is mostlikely in your video card.

• Make sure that your system is configured properly for your video card/monitor combination. Right-click anywhere on the desktop and selectProperties to display the Display Properties dialog box; use the Settingstab to select the correct hardware and configuration settings.

• If your monitor suddenly goes blank and emits a high-pitched whine, turnoff your monitor - immediately. Leaving the monitor on in this condition

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could damage it. Now check the settings on your video card (or in Windows'Display Properties dialog box); chances are the configuration is set to ahigher resolution than your monitor is capable of displaying. Reconfigurethe settings for a lower-resolution display, and you should be fine.

• If your monitor pops and crackles and maybe even starts to smell (likesomething's burning), turn it off immediately. While it's possible that all thistrouble is caused by dirt building up inside your monitor, it's more likelythat something major-like the power supply-has gone bad, and that it's timeto invest in a new monitor.

Your Modem won't Connect

In this interconnected world, we all need the Internet to survive. What do youdo if your modem won't let you connect/

• Check your cables! If you're using an external modem, make sure it's firmlyconnected to the correct port on your PC, and that it's plugged into andreceiving power from a power strip or wall outlet. If you're using an internalmodem, make sure that card is firmly seated. For all modems, make surethat it's connected to a working phone line - and that you have the cableconnected to the in jack on the modem, not the out jack!

• Make sure your modem is configured correctly. If you're using Windows 98,Me or XP, use the Modem Troubleshooter to track down potential problems.Otherwise, go to Control Panel and start the Modems applet, then run thediagnostics in the Modem Properties dialog box. If problems persist, tryuninstalling and then reinstalling the modem on your system and thencheck whether an updated driver is available from the modem vendor.

• Check your dial-up configuration. Make sure you have the right phonenumbers listed, that you've entered the correct username and password,and that any Internet service provider (ISP) - specific information (such asDNS numbers) is entered properly.

• Check your system network or TCP/IP settings. This isn't so much a problemwith Windows Me/2000/XP, but it can be an issue with Windows 98/NT andother operating system.

Also, remember that just because you can't connect to your ISP doesn't meanthat you have a modem problem. Many ISPs try to connect too many usersthrough too few phone lines, resulting in busy signals, slow connections,dropped connections, or similar problems. See whether your connectionproblems ease up at different times of the day (the after-dinner period is atypical "rush hour" for most ISPs), or if your ISP has different numbers that youcan use to connect. If the problem persists, consider changing ISPs.

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Your Printer won't PrintPrinter problems are quite common-especially after you've just hooked up anew printer to your old system. Here are a few things to look for:

• Make sure that your printer is plugged in and has power, and that it isconnected properly to your PC. A loose printer cable can cause all sortsof bizarre problems.

• Along the same lines, make sure that your printer isn't out of paper, andthat it's online and not experiencing any type of paper jam.

• Make sure that Windows recognizes your printer - and that it recognizesthe correct printer. (Recognizing a similar model from the same manufacturerdoesn't cut it). Make sure that Windows has the correct printer driverinstalled. You may even want to check with the manufacturer to make surethat one has the latest and greatest version of the printer driver.

• If you have more than one printer installed on your system (including faxesand devices that your system sees as printers), check the Print dialog boxto make sure you have the correct printer selected.

• Check for device conflicts. Fax machines and printers frequently interferewith each other, but any two devices, if not configured properly, can causeconflicts.

• Make sure you have enough free disk space to print. Windows will usetemporary hard disk space (called a cache) to store data while a print jobis in process. Try deleting old and unused files (including TMP files in the\WINDOWS\TEMP\ folder) to free up additional disk space.

Date post:	05-Aug-2015
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