IT Fundamental

8/3/2019 IT Fundamental

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COMPUTER

FUNDAMENTALS


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Some Basic Terms

Hardware - the equipment associated with a computer system

Software - the instructions that tell a computer what to do

Information -consists of facts and items of knowledge. It

can be anything that has meaning to people .

Ex-Name & Address ,Map

Data - is information in which it can be processed.

Ex - A word processed letter stored on a floppy disc


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Applications SoftwareApplications Software -- software that issoftware that isused to solve a particular problemused to solve a particular problem

ProgramProgram -- set of stepset of step--byby--step instructionsstep instructionsthat directs the computerthat directs the computer

Computer ProgrammerComputer Programmer -- person whoperson whowrites programswrites programs

UserUser -- people who purchase and usepeople who purchase and usecomputer softwarecomputer software


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Hardware

The equipment associated with a computer system


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Data Processing

A computer is a machine that accepts data (input) andprocesses it into useful information (output).

INPUT(DATA)

PROCESSOROUTPUT

(INFORMATION)

Figure 1.1 A simplified representation of a computer


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Primary Components of a Computer System

Input Devices accept data in a form the computer can use.

The Central Processing Unit (CPU) has the electronic

circuitry for manipulating input into the information wanted.

Memory temporarily holds data and instructions needed

by the CPU.

Output Devices make the processed data available for use.

Secondary Storage Devices store additional data and

programs.


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Primary Components of a

Computer System


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CPU transforms raw data into processed information

CPU consists of electronic circuits that;interprets and execute program instructions

communicate with I/O and Storage devices

Memory or Primary storage

hold data both before and after it is processedholds instructions (programs) needed


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General computer concept

The computer as an information-processing device performsfive basic functional operations.

The Input function

The Output function

The Storage (Memory) function

The Arithmetic/Logic (ALU) function

The control function


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CPU

Input Storage Output

Arithmetic/

LogicControl

Information

Control

Figure 1.4 Functional Block Diagram of a Digital Computer


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Flow of Information

All information that the computer possesses must

be entered via the Input function

Depending on the type of information, it may be

used to tell the computer what to do instructions

OR

it may be used as data in arithmetic or logical

operations Data


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the information tells the computer where the nextinformation is stored or what to do with the next packet of

information obtained

it will be routed to the Arithmetic/Logic function for

processing and back to await its next use

As an instruction,

As data,

All instructions and data are placed in the

memory (storage)


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All instructions and data are placed in the

memory (storage)

Instructions and data are processed sequentially as

required by the stored program and the

intermediate/final results are returned to storage

The output function displays the results of the internal

processing of information when called upon by the control

function


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Common Input Devices

Typing on a keyboard Pointing with a mouse

Writing with a pen-based

computer system

Speaking to a voice inputsystem

Scanners.

Document readers.


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MouseMouse

Amouse is an input device designed to fit snuglyAmouse is an input device designed to fit snugly

under a hand while it is moved about over a tableunder a hand while it is moved about over a table

Uses of mouseTo select options from a menu or from a set of icons.

To position the cursor when editing text or using a design

packages.

To select an object in a drawing or a piece of text to becopied, moved or deleted.


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Document ReadersDocument Readers

OMR, OCR and MICROMR, OCR and MICR-- A document reader is aA document reader is adevice which read data straight from adevice which read data straight from aform.form.

ExExOptical Mark Recognition(OMR)Optical Mark Recognition(OMR)

Optical Character Recognition(OCR)Optical Character Recognition(OCR)

Magnetic Ink Character Recognition(MICR)Magnetic Ink Character Recognition(MICR)


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Optical Mark RecognitionOptical Mark Recognition. (OMR). (OMR)

OMR is a system of reading lines or marks which haveOMR is a system of reading lines or marks which havebeen made in exactly the right positions on a card orbeen made in exactly the right positions on a card ordocument.document.

Applications of OMR

The documents to be read have empty boxes to takethe marks. These have been preprinted on to the

documents together with information telling the userwhat to do. The person preparing the data makes pencilor ink marks in the appropriate boxes.


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Optical Character Recognition (Optical Character Recognition (OCR)OCR)

An optical character reader can recognizeAn optical character reader can recognizecharacters from their shape. As with OMR light ischaracters from their shape. As with OMR light isreflected from the paper and form the ink. In OCRreflected from the paper and form the ink. In OCR

however the reader has to workout what thehowever the reader has to workout what thecharacters are.characters are.

Magnetic Ink Character Recognition.(MICR)

An MICR reader recognizes characters formed frommagnetic ink


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The Processor and Memory:

Data Manipulation

The CPU is responsible for transforming

raw data into processed information.

The CPU consists of electronic circuits that interpret

and execute program instructions, as well as communicate

with the input, output, and storage devices.

Memory or primary storage holds data input to the

system, both before and after it is processed. It also holds the

programs needed by the CPU.


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Common Output Devices

Screens can produce lines of written or numericaldata and / or color graphics displays.

Printers produce printed materials under the control

of a computer program.


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There are several ways to produceThere are several ways to produceoutput:output:** Text output.Text output.* Graphics output.* Graphics output.* Sound output.* Sound output.

* Video output.* Video output.


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Basic Clarification of PrintersBasic Clarification of Printers

Character printers.Character printers. -- Prints one character at a time.Prints one character at a time.

Line printersLine printers Prints one line at a time.Prints one line at a time.

Page printersPage printers Prints one page at a time.Prints one page at a time.

Basic methods of producing printouts

Impact printers:

Form characters or images by striking mechanismSuch as print hammer or wheel against an inkedribbon leaving an image on paper.


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Impact printers: conti

Dot matrix printer

This mechanism enable the print control up to thedot level on the paper, can be used to produce bothtext and graphics


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NonNon--Impact printersImpact printers

Form characters or images without making directForm characters or images without making directphysical contact between printing mechanism andphysical contact between printing mechanism andpapers.papers.


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Laser printerLaser printer

Excellent print quality and font selection.Excellent print quality and font selection.

Fast printing and high quality graphics with color, highFast printing and high quality graphics with color, highresolutionresolution

Medium level noise but high cost.Medium level noise but high cost. Primary disadvantages are expensive maintenance and thePrimary disadvantages are expensive maintenance and the

high cost of toner cartridges.high cost of toner cartridges.

Ink-Jet printers

Ink jet printers transfers characters and images to thepaper by spraying a fine jet of ink.Offers nearly thequality of laser printing but not the speed, Low cost

alternative for high quality printing


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MonitorMonitor

Provide soft copy out put comes in either monochrome orProvide soft copy out put comes in either monochrome orcolor.color.

Amonochrome display a single color against a differentAmonochrome display a single color against a differentcolor backgroundcolor background

Color display can show variety of colorsColor display can show variety of colors..Plotters

It is a specialized output device designed to produce high quality graphics

in a variety of colors.Type of plottersPen plotterElectrostatic plotter.Thermal plotter.


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Storage Devices and Stored Data

Secondary Storage is Needed

Since

Memory is limited in size and

is temporary (volatile).


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Magnetic Storage

The operation of both disk drives and tape units is

virtually the same:

one records data on a flat platter coated with

a magnetic material,

while

the other records data on a thin band of flexible plastic

coated with magnetic material


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Magnetic Disks

Metal or plastic disk coated with magnetic oxide.

Types

Disk Packs

Hard DisksDiskettes

Data is recorded as magnetic spots on concentric tracks

Rotation

ActuatorDisk

The magnetic disk

Head


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Diskettes

Also called floppy disksTwo primary types

3 1/2" Diskette

5 1/4" Diskette

3 1/2" Diskette

Double Sided / Double Density (DD): stores 720 Kbytes.Double Sided / High Density (HD): stores 1.44 Mbytes.


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Hard Disks

Set of disks, but metallic, not plastic.

Usually 5 1/4" or 3 1/2"

Enclosed in PC so doesn't need special environment

(also called Winchester disks)

Direction of motion

Actuator

Heads

Disks

The multi disk drive

(Hard disk drive)


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Optical Storage

Data is recorded with a laser hitting a layer of metallic

material, producing tiny spots on the disk's surface.

Data is read by scanning the disk with a laser,

picking up reflections from the spots on a lens.

CD-ROM

(Compact Disk Read-Only Memory)

Similar to audio CD media.

Can hold up to 600 Mbytes of information.

Slower access time than magnetic disks.


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Write-Once, Read Many (WORM) Disks

Written once by user,

then becomes a read-only media.

Combined Magnetic and Optical Recording

eg.Magneto-optical (MO) disks


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Magnetic Tape

Information recorded in binary form bymagnetization of spots on tape coated with

ferrous oxide.

Inexpensive means of storing large amountsof information.

Useful for operations that require sequential

processing and for backing up.


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Secondary Storage

Additional storage separate from the CPU and memoryMagnetic disk - oxide-coated disk - can be a diskette or hard

disk.

Magnetic tape .

CD-ROM, compact disc read-only memory optical storage.


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The CompleteHardware System

Hardware devices attached to a computer are called

peripheral equipment.

With personal computers, some peripherals may be

built into the same physical unit.

In large computer systems, the input, processing,

output, and storage functions may be in separate rooms,

buildings, or even separate countries.


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Classifications of Computers

Mainframes and Supercomputers

Minicomputers

Personal Computers and Workstations


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Mainframes and Supercomputers

Capable of processing large amounts of data atvery high speeds

Large, expensive over $1M.


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Minicomputers

Smaller, slower and less costly than mainframes.Used by many small businesses.

Personal Computers (PCs) and Workstations

Small, inexpensive - $500 - $3000.

Used for business and home use.

High performance workstations are

often used for scientific andengineering work.

Distinction between PCs and

workstations becoming hazy as

PCs become more powerful.


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Data CommunicationsThe process of exchanging data over communications

facilities.Computer networks that connect computers and their

resources are becoming more widespread.

A network that connects computers in one location is called a

local area network (LAN).


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Software

Packaged software for PCs usually comes on diskette or

CD-ROM for installation on the hard drive.

"User friendly" software can be learned with a minimum

of training.

Application Soft are


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Application Software

Word processing / desktop publishing lets you create,

edit, format, store, print text and graphics in a document.

Electronic spreadsheets organize business data into rows

and columns for analysis.

Database managementprograms allow users to manage

large collections of interrelated data.

Graphics packages display information in visual forms:maps, charts, and visual presentations.

Data communications software allows for accessing

remote computers via phone lines.


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Programming

Programs are written in a variety of programming

languages.

Some languages are very English-like (high level) while

others are more difficult to follow (low level).


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Computer People

The Management Information Systems (MIS), or

Computing Services, orInformation Services department

is usually responsible for computer resources within an

organization.

Data entry operatorsprepare data for processing.

Computer programmers design, write, test, implement,update, and maintain the programs that process data.


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Systems analystsplan and design computer systems.

The chief information officer (CIO) oversees the MISdepartment and is responsible for the technological goals and

operations of the entire organization.


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NUMBER SYSTEMSNUMBER SYSTEMS

DECIMAL SYSTEMDECIMAL SYSTEM

Notice the simplicity of multiplying 12Notice the simplicity of multiplying 12 1414

by using the present system:by using the present system:

14

12

14

168


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BINARY SYSTEMBINARY SYSTEM

The same type of positional notation is used in theThe same type of positional notation is used in the

binary number system as in the decimal system.binary number system as in the decimal system.

DECIMAL BINARY DECIMAL BINARY

1 = 1

2 = 103 = 11

4 = 100

5 = 101

6 = 110

7 = 1118 = 1000

9 = 1001

10 = 1010

11 = 1011

12 = 110013 = 1101

14 = 1110

15 = 1111

16 = 10000

17 = 1000118 = 10010

19 = 10011

20 = 10100


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101 = 1 23-1 + 0 23-2 +123-3

= 1 22 + 0 21 + 1 20

= 4 + 1 = 5

11.011 = 1 22-1 + 1 22-2 + 022-3 + 1 22-4 + 1 22-5

= 1 21 + 1 20 + 0 2 -1 + 1 2-2 + 1 2-3= 2 + 1 + +

= 3

BINARY ADDITION AND SUBTRACTION

0 + 0 = 0

0 + 1 = 11 + 0 = 11 + 1 = 0 plus a carry over of 1


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BIN ARY SUBTRACTIONBIN ARY SUBTRACTION

00--0=00=0

11--0=10=1

11--1=01=0

00--1=11=1

A few examples will make the procedure forbinary subtraction clear;


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Decimal Binary Decimal BinaryDecimal Binary Decimal Binary

9 1001 16 100009 1001 16 10000--55 --101101 --3 113 11

1001004 110113

BINARY MULTIPLICATION ANDDIVISION

0 0 = 0

0 1 = 01 1 = 11 0 = 0


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DECIMAL BINARY DECIMAL BINARYDECIMAL BINARY DECIMAL BINARY

1212 1100 1021100 102 11001101100110

1010 10101010 88 10001000

120 00001100

00001100

1111000

816 1100110000

0 1 = 01 1 = 1

Here are the two examples of division:


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DECIMAL BINARY DECIMALDECIMAL

55 101 2.416101 2.4165 25 101 11001 12 29.00005 25 101 11001 12 29.0000

101 24101 24101 50101 50

101 48101 4820201212

80807272

8p.t.o


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BINARYBINARY

10.011010101

11101.0011001100

101001100100001100100001100


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CONVERTINGDECIMALNUMBERS TOCONVERTINGDECIMALNUMBERS TO

BINARYBINARY

125125 2 = 62 + remainder of 12 = 62 + remainder of 1


3131 2 = 15 + remainder of 12 = 15 + remainder of 11515 2 = 7 + remainder of 12 = 7 + remainder of 1


33 2 = 1 + remainder of 12 = 1 + remainder of 111 2 = 0 + remainder of 12 = 0 + remainder of 1

125 = 11111012125 = 11111012


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CONVERTINGBINARY NUMBERS TOCONVERTINGBINARY NUMBERS TODECIMALDECIMAL

11 2626 = 64= 64

11 2525 = 32= 32

11 2424 = 16= 1611 2323 = 8= 8

11 2222 = 4= 4

00 2121 = 0= 011 2020 = 1= 1


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conversion of decimal fractionsconversion of decimal fractions

0.865 1 2-1 = 0.875 0.5 = 0.375

0.375 1 2-2 = 0.375 0.25 = 0.125

0.125 1 2-3 = 0.125 0.125 = 0


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BINARY NUMBER COMPLEMENTSBINARY NUMBER COMPLEMENTS

11011 1101111011 11011

--10100 = 0110010100 = 01100

00111 1 0011100111 1 00111

Carry is dropped

BINARY CODED DECIMAL NUMBER


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BINARY CODEDDECIMALNUMBER

REPRESENTATION

BINARY CODE DECIMAL DIGIT

0000

0001

0010

00110100

0101

0110

0111

10001001

0

1

2

34

5

6

7

89

This is known as a binary coded decimal 8, 4, 2, 1

code or simple BCD

.


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OCTAL ANDHEXADECIMALNUMBEROCTAL ANDHEXADECIMALNUMBERSYSTEMSSYSTEMS

1213 in octal is 11213 in octal is 1 83 +283 +2 82 + 182 + 1 81 + 381 + 3 80 = 512 +128 + 8 + 3 = 651 in decimal.80 = 512 +128 + 8 + 3 = 651 in decimal.

111110111 = 767 octal110110101 = 665 octal

11011 = 11 octal

Eg:


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For instance, to convert decimal 200 to an octalFor instance, to convert decimal 200 to an octalrepresentation, we divide as follows:representation, we divide as follows:

200200 2525 reminder is 0reminder is 0




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