eBook Module 1 Concepts of IT (Information Technology)

Module 1:

Concepts of IT(Information Technology)

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Module 1: Concepts of IT (Information Technology)Copyright © 1992–2006 Align Media Inc.All rights reserved06–0713

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Tableof contents

1 Computerfamilies

Chapter objectives 1Types of computers 1Mainframes 1Minicomputers 2Personal computers 3Personal digital assistant 4Supercomputers 5Networks 6The Internet 7Intranets 7Extranets 8Humans or computers 8Review exercises 9

2 Hardwareconcepts

Chapter objectives 13Hardware basics 13Bits and bytes 14CPU 14Bus standards 15Ports 15PCMCIA slots 16USB ports 16Plug–and–Play 16Expansion card 16Speed versus cost 16Analog versus digital 17Review exercises 17

3 Memoryand storage

Chapter objectives 21Capacity 21CPU cache 21RAM 22

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Module 1: Concepts of IT (Information Technology)

ROM 22Diskette drives 22Diskettes 23Handling diskettes 23Formatting disks 24Zip disks 24Hard disks 25CD–ROMs 25CD–ROM drives 26DVD–ROM drives 27Tape drives 27Review exercises 28

4 Peripheraldevices

Chapter objectives 31Screen monitor 31Keyboard 33Mouse 34Trackball 34Lightpens 35Printers 36Plotters 37Modems 38Scanners 39Joysticks 39Touch–screen technology 39Digital cameras 40Cameras 41Microphones 41Speakers 42Review exercises 43

5 Networkbasics

Chapter objectives 47Information technology 47Networks 48LANs and WANs 48Wireless LAN 49Reasons for networks 49Workstations 50Servers 50Client / server architecture 51Nodes 51Domains 51Network interface cards 51Cabling 52

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Network connectors 52Telephone networks in computing 52Local vs. shared devices 53Shared drives 53Teleworking 54Review exercises 54

6 Operatingsystems

Chapter objectives 59Software and data files 59File names and extensions 60Purpose of operating systems 61Running multiple applications 62Operating system evolution 62DOS 62Graphical user interfaces (GUI) 63Windows 3.1/3.11 64Windows 95 65Windows NT Workstation 66Windows 2000 Professional 67Windows 98 67Windows Me 68Windows XP 68Windows NT Server 69Windows 2000 Server 70Windows 2003 Server 70Novell NetWare 70Unix 70Linux 71Review exercises 71

7 Systemsdevelopment

Chapter objectives 75Analysis and design of computer programs 75Programming and testing of computer programs 76Review exercises 77

8 Applicationsoftware

Chapter objectives 79Software versions 79Application programs 79Wordprocessing applications 80Spreadsheet applications 80

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Presentation applications 81Database systems 82Desktop–publishing applications 82Graphic art design applications 83Contact management applications 84Large–scale computer applications 84Review exercises 85

9 Additionalsoftware

Chapter objectives 89World Wide Web browsers 89Electronic mail programs 90Games 90Reference tool software packages 91Educational software packages 91Virus programs 92Antivirus programs 92Utilities programs 93Review exercises 94

10 Overviewof the Internet

Chapter objectives 97Understanding the Internet 97Origins of the Internet 97The World Wide Web (WWW) 98Web browsers 98Links 99Web sites 99Web servers 100Internet addresses and domain names 100Domain types 101Web addresses 101Search engines 101E–mail 102E–commerce 103Review exercises 104

11 Health, safety,and environment

Chapter objectives 107Ergonomics 107Safety 108The environment 108Review exercises 109

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12 PCsecurity

Chapter objectives 111Information security 111Passwords 111Understanding viruses 112Effects of viruses 113Preventing infection 114Checking for viruses 115Review exercises 115

13 Intellectualproperty

Chapter objectives 117Understanding copyrights 117Proprietary, shareware and freeware software 118Review exercises 118

14 Indexof terms

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Page 6 •

1 Computerfamilies

Chapter objectives By the end of this chapter you will be familiar with the following topics:

• Types of computers• Mainframes• Minicomputers• Personal computers• Personal digital assistant• Supercomputers• Networks• The Internet• Intranets• Extranets• Humans or computers

Types of computers Computers can be classified roughly as follows:

• Mainframes

• Minicomputers

• Personal computers

• Supercomputers

• Networks

Mainframes A mainframe is a computer to which thousands of terminals can be connected so that thousands of users work at the same time. A terminal consists of, basically, a screen monitor

Tell students that sometimesthe distinction between types

of computers becomesblurred.

Remark that mainframeswere the first type ofcomputer developed.

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and a keyboard. That is, a terminal has no computing power of its own—the computing power resides in the main computer (the mainframe), and all users share that power.

Mainframes are normally used by large corporations with tens of thousands of employees and government agencies. IBM is the largest manufacturer of mainframe computers in the world.

Some uses of a mainframe could be

• Processing incoming stock trades at a bank

• Running an Internet server at an online auction Web site

• Replacing a large number of smaller servers at a large business

Minicomputers A minicomputer is a computer to which tens or hundreds of terminals can be connected so that tens or hundreds of users work at the same time. That is, a minicomputer is like a State that as PCs have

become more powerful, thedistinction between personal

computers andminicomputers has become

blurred.

Page 2 • 1 Computer families


mainframe, but it is less powerful. As in the case of mainframes, the users share the computing power of the minicomputer.

Minicomputers normally are used by medium–size corporations, by departments of large corporations and departments of government agencies. IBM, Hewlett–Packard and Digital manufacture minicomputers.

Personal computers A personal computer, in its simplest form, can be described as a computer to which only one terminal (i.e., only one screen monitor and one keyboard) is attached. That is, a personal computer is like a mainframe or a minicomputer with only one user—hence its name “personal computer” or “PC” for short. Of course, since it has to serve the needs of only one user, a personal computer has less computing power than a minicomputer or a mainframe. However, this is not to say that PCs are not powerful. Quite the contrary, PCs can be used to run company departments or small businesses. Also, bear in mind that a standard PC nowadays has more computing power than a mainframe did thirty years ago. The cost of PCs has come down so much that they have become commonplace in corporations the world over and are becoming in the home as common as VCRs or CD players. PCs are manufactured by companies like IBM, Compaq, Hewlett–Packard, Dell, etc.

PCs can be desktop PCs, notebooks or palmtops. A desktop PC is a PC designed not to be portable but to sit on your desk more or less permanently. In a desktop PC, the computer, screen monitor and keyboard come as three separate pieces of hardware.

State that although theacronym PC is used to refer

to Intel–basedmicrocomputers, other

microcomputers (e.g., theMacintosh) are also personal

computers.

1 Computer families • Page 3


As its name indicates, a notebook is a PC the size of an 8.5” by 11” notebook. Notebooks have been designed with portability in mind—the computer itself, screen monitor and keyboard are all integrated into a single case that is light in weight and easy to carry. Before manufacturers managed to fit a whole PC into an 8.5” by 11” case, a portable computer was called a “laptop”, for users could work with it by placing it on their laps. All major computer manufacturers make notebooks, including IBM, Compaq, Hewlett–Packard, Toshiba, Dell, etc.

A palmtop is a PC of reduced size that can be held on one’s hand. Palmtops offer great portability, but sacrifice screen size and the comfort of a regularly sized keyboard. Popular palmtops include those manufactured by Hewlett–Packard.

Personal digitalassistant

Personal digital assistant (PDA) is a small mobile hand–held device that allows you to store and retrieve information for personal or business use. A PDA is commonly used for keeping track of your appointments, addresses, telephone numbers, email addresses, play music, and record voice memos. The most recent PDAs allow you to retrieve your emails, and get access to the Internet by either connecting to a telephone jack, (whereby a special modem may need to be purchased), or wirelessly by buying a wireless modem or by connecting to certain types of digital mobile phones. For this type of connection you need to subscribe to a wireless data



network service. Lastly, there are some PDAs which allow you to access your email and the Internet without having to purchase any additional hardware or software.

PDAs are often referred to as handheld devices due to their compact size (they often fit in the palm of your hand). Most PDAs have a small keyboard, as well as an electronically sensitive pad that allows you to enter the desired information using a stylus pen. PDAs work on either a Windows–based (e.g., Windows CE) or a Palm operating system. The more enhanced PDAs are equipped with a word processor, spreadsheet, money manager, and e–books reading programs. Some of these programs, however, are mini versions of their desktop counterparts. For example, the Compaq handheld device (the IPAQ) has the Windows CE operating system, with Microsoft Word and Microsoft Excel. The version of these applications perform only the basic wordprocessing and spreadsheet capabilities. For example, you cannot insert tables in Word for Windows CE, add pivot tables in Excel for Windows CE, etc.

PDAs run on rechargeable batteries that can be replaced, or simply on standard alkaline batteries. Other PDAs run on permanent rechargeable batteries. A PDA usually has anywhere between 2 MB to 32 MB of memory. Additional memory can be installed in the form of small storage cards. Normally, two MB of memory is sufficient to enter information in the address books, to maintain an active calendar, take notes, and load useful programs. To store large software programs, digital photographs, or audio recording, more memory may be necessary.

One of the most useful features of a PDA is that you can enter information and have the same information in your desktop computer or vice versa. This exchange of information is available when you purchase a cradle with your PDA. This cradle is connected to your desktop or your laptop, and allows you to synchronize the information which is in your PDA with the information in your desktop or laptop.

Supercomputers Supercomputers are extremely powerful machines that can be general–purpose machines (like mainframes) designed to complete different types of tasks, or specific–purpose machines that have been designed to perform a particular type of task (e.g., solve specific types of mathematical equations). In either case, supercomputers are used to perform tasks that would

Indicate that supercomputersare used for both pureresearch (e.g., proving

complex theorems in puremathematics) and to solve

practical problems (e.g.,predicting hurricane paths).



take too long to complete by less powerful computers (e.g., performing all the mathematical calculations necessary for accurate weather forecasting for the evening news broadcast).

Supercomputers are extremely expensive machines. Thus, in most cases they can be afforded only by governments, universities and very large corporations. However, the organizations that have invested in supercomputers often rent their computing power to smaller companies so that they can have complex problems solved in time without having to purchase a supercomputer.

Some uses of a supercomputer could be

• Predicting the weather

• Playing chess

• Researching climate change

• Physical simulations

Networks A computer network is a group of computers that have been interconnected with one another for the purpose of sharing data or devices.

A network can be as simple as two desktop PCs sharing a printer or as complex as several hundred or even thousands of machines, some of which could be notebooks, desktop PCs, minicomputers, mainframes or supercomputers.

State that a network is acomputer system itself made

up of computers.



The Internet The Internet consists of thousands of computers of all types around the world which are interconnected in a variety of ways (e.g., through the telephone system or through cable) so that they can send and receive data. These computers are called Internet servers, and they reside in universities, government agencies, corporations and other organizations.

You do not need to have an Internet server to connect to the Internet and thus send or receive, for example, electronic mail to and from other people also connected to the Internet. Instead, individual users can connect to an Internet server maintained and serviced by a company which is an Internet service provider (ISP). For a monthly or yearly fee, you can connect to the Internet server of an ISP through the telephone line via a modem attached to your PC. That is, your PC can be connected to the Internet server of an ISP, which in turn is the gateway to the rest of the Internet worldwide.

Once you are connected to the Internet, you can send and receive electronic mail, see on your screen the pages of information, advertisements, job offerings, product catalogues, etc. that tens of thousands of different companies have posted on the Internet’s World Wide Web (WWW), etc. If you choose to do so, you can also create (or have created by someone else) your own page of information and post it on the Internet’s World Wide Web so that visitors can see what you have to offer or say.

Intranets Intranets are proprietary, smaller versions of the Internet. A large company may decide to post a corporate directory of names, positions, addresses and phone numbers of its employees on the Internet for all employees to see. However, if the company does not want the rest of the

State that the Internet is theworld’s largest network.

Remark that intranets arebecoming widespread.



Internet users to access that information, it may decide to create its own private Internet (an intranet) to which only company employees have access.

Extranets Extranets are similar to Intranets, which are proprietary smaller versions of the Internet. Typically large companies provide services to their employees over the corporate Intranet. This works for all employees working on–site. However, if employees are not on location at the office they may still need to access the corporate Intranet. In this case an Extranet is used.

An Extranet uses various Internet protocols, telecommunications systems and security measures to allow employees to securely access the Intranet remotely.

Humans orcomputers

Humans are excellent at performing creative tasks. However, computers excel at redundant tasks that require speed and accuracy.

In the modern computing environment computers perform many tasks that a human would either not want to do, or not be capable of doing. For example, consider a bank that receives orders for stock market trades. The bank may receive several thousand requests per second, a rate that no human could keep up with. Also, the trade would have to be executed exactly as requested, any mistakes could cost money. A computer excels at tasks like these.

As another example, consider a political Web site that critiques the actions taken by a government. A computer is not capable of creating quality, unique commentary that a human would want to read. A computer could not provide insight into the words and actions of a human. This is a task that a human could excel at.



R E V I E W E X E R C I S E S

Remarks Make sure that copies of any files needed to complete the following exercises have been saved to the folder My Documents (or to some other suitable folder) in your system. Then, use the resulting copies in My Documents to complete the exercises whenever required, unless otherwise indicated.

Exercise one List below three different types of computers.

Exercise two Briefly describe below what a computer network is.

Exercise three What are companies that allow users to connect to the Internet for a monthly or yearly fee called?

Answer—Any three of:mainframes, minicomputers,

personal computers,supercomputers, networks.

Answer—A computer networkis a group of computers that

have been interconnectedwith one another for the

purposes of sharing data ordevices.

Answer—Internet serviceproviders (ISPs).



Exercise four List below the name of three major manufacturers of notebooks.

Exercise five What are the two hardware devices a terminal basically consists of?

Exercise six What types of computers can be part of a network?

1 Desktop PCs

2 Supercomputers

3 Notebooks

4 Mainframes

5 Minicomputers

6 All of the above

Exercise seven Intranets are private, smaller versions of the Internet.

1 True

2 False

Exercise eight Write below what “WWW” stands for.

Answer—For example, anythree of: IBM, Compaq,

Hewlett–Packard, Toshiba,Dell.

Answer—A screen monitorand a keyboard.

Answer—Choice 6.

Answer—True.

Answer—”World WideWeb”.



Exercise nine Write below what “ISP” stands for.

Exercise ten Which is the largest manufacturer of mainframe computers in the world?

1 Compaq

2 Hewlett–Packard

3 IBM

4 Toshiba

5 None of the above

Answer—”Internet serviceprovider”.

Answer—Choice 3.




2 Hardwareconcepts


• Hardware basics• Bits and bytes• CPU• Bus standards• Ports• PCMCIA slots• USB ports• Plug–and–Play• Expansion card• Speed versus cost• Analog versus digital

Hardware basics The two main components of a computer are the software and the hardware. Both components are required for the computer to perform useful work. Typically the user interacts with the software which in turn interacts with the hardware. Hardware is any physical piece of equipment that helps the computer to run, this includes external devices like

• Keyboards

• Printers

• The mouse

• Monitors

• Trackballs

But more often hardware refers to internal devices like

• Central processing units (CPU)

• Hard drives

• RAM

• Video cards

• Audio cards

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• Motherboards

Once given instructions from the software, these devices act together to add and subtract numbers, store information, play sounds, display pictures and video, print documents and access the Internet.

Bits and bytes Understanding computers begins with understanding the concept of a bit. In computing, a bit is the smallest piece of information that can be created, identified, stored and transferred.

Generally speaking, all a computer can do is to detect two different electrical states—whether voltage is present (turned on) or not present (turned off). The ON electrical state is represented by a one (1), and the OFF electrical state is represented by a zero (0). That is why we normally say that computers internally work with just 1s and 0s (the binary system)—all the graphics, colours, text, calculations, sounds, etc. that your computer produces are ultimately a huge combination of 1s and 0s. In other words, everything that a computer produces is the result of switches (called “gates”) which are constantly turned on and off at high speed to form combinations of voltage and lack of voltage.

In a string of 1s and 0s, each 1 and each 0 is a bit. Combinations of the bits can represent letters of the alphabet, symbols, etc. For example, the upper case letter B would be represented by 01000010; the lower case letter b by 01100010; number 9 by 00111001; and the ampersand (&) by 00100110. Notice that each of the combinations lists eight bits. A combination of eight bits is called a byte.

CPU The CPU (central processing unit), microprocessor or, simply, processor, is a chip in your computer where information is processed.

The speed and capabilities of your microcomputer largely depend on the kind of CPU it has. Most personal computers use CPU chips manufactured by Intel Corporation. Most PCs being sold today use Intel’s 80686 (Pentium II) CPUs or Intel’s 80586 (Pentium) CPUs. Previous (and slower) Intel CPUs (such as the 80486, 80386, 80286, etc.) have been discontinued and are now obsolete or are being retired from corporations to be replaced by the newer (and faster) ones.

Aside from Intel Corporation, there are other chip makers in the market, For instance, the original Apple Macintosh used the Motorola 68000 chip as its microprocessor. Digital produces the Alpha chip and IBM, in conjunction with Motorola, produces the Power PC chip.

Each CPU has a timer or clock that handles instructions at a constant rate. This timer works on a cycle which is measured in Hertz. If the CPU has to perform complicated instructions,

Remark that computersystems ultimately

understand only whethervoltage is present (ON) or

not present (OFF), and thateverything a computer system

does can be expressed interms of 1’s (ON) and 0’s

(OFF).

Tell students that the CPU isthe most important

component in a computersystem. In fact, one can think

of the CPU as being thecomputer while everythingelse (memory, disk drives,

etc.) as being mereperipheral devices.

Page 14 • 2 Hardware concepts


then it may take several cycles to complete its task. The faster the clock’s speed the faster the data processing time. For example, a 486 chip with a 66 MHz clock speed is faster than a 486 chip with a 33 MHz clock speed. At the time of writing, chips running at 133, 166, 200 and 233 MHz are common and Pentium chips running at 266 and 300 MHz are becoming increasingly popular.

Bus standards Transfer of data is a large part of what the CPU must do in any process. For example, there is transfer of data when loading files from a disk. Likewise, images projected on the screen must go through a data channel. The primary factor limiting the data transfer speed is the size of the input/output bus. Thus, aside from the type of CPU (Pentium, II, Pentium, etc.) and CPU clock speed (200 MHz, 166 MHz, etc.), the input/output bus also plays an important role in the overall speed at which a personal computer works. As it might be expected, the data transfer capabilities of the input/output bus have been improved over the years.

Ports So far, we have discussed the internal concepts of data transfer but, as you know, the computer must communicate with other devices that are not internal (e.g., mouse, screen monitor, printer, etc.)—these are called peripheral devices. The screen monitor that you use to view the document that you type is considered an output device since the computer must send the appropriate commands to the monitor. The keyboard, on the other hand, is an input device since the computer receives the commands from the keyboard. Each of these devices must be connected through an I/O (input/output) port.

There are serial ports and parallel ports. Though a serial port could be used to connect a printer to the computer system, normally printers are connected through a parallel port. Parallel ports are named LPT1, LPT2 or LPT3. For example, most often you will see that a laser printer is connected to the PC via the parallel port LPT1.

Parallel ports are faster than serial ports because they can transfer data one byte at a time.

Serial ports are labelled COM1, COM2, COM3 or COM4. Serial ports are normally used to connect devices like the mouse, modem and others to the computer. For example, most often the mouse is connected to the PC via the serial port COM1.

Serial ports are not as fast as parallel ports because they can transfer data only one bit at a time.

Indicate that the bus standardis important when deciding

what computer system topurchase.

Tell students to be careful notto bend or break the pins in

the ports and connectors.

2 Hardware concepts • Page 15


PCMCIA slots Laptop computers used to lack a standard for expansion slots. This lead to a small, proprietary expansion–board market for laptops, which, among other things, made it difficult for a laptop user to increase the amount of memory in his or her system. Japanese memory vendors solved this problem by forming the Personal Computer Memory Card Industry Association (PCMCIA) and by designing a standard for plug–in memory cards. The standard became so popular that it was readily extended to include modems and hard disks as well.

USB ports Universal Serial Bus (USB) is a plug–and–play interface between a computer and an add–on device, for example audio players, joysticks, keyboards, telephones, webcams, scanners, and printers. USB ports allow you to add a new device to your computer without having to add an adapter card or even having to turn the computer off.

The advantage of a USB port as opposed to parallel ports is the speed at which the data is transferred. USB ports support a data speed of 12 megabits per second. This speed accommodates a wide range of devices, including MPEG video devices, data gloves, and digitizers.

Plug–and–Play In earlier computer systems, users were required to tell the computer that a new device was being added to the computer. Plug–and–Play (PnP), on the other hand is a capability developed by Microsoft in 1995 for its operating systems which allows users to plug a device (e.g., Web Cam, scanner, digital cameras, etc.) into a computer and have the computer recognize the presence of the device immediately. This is an improvement to having to tell the computer, through the operating system, that you are plugging a new device.

Expansion card An expansion card (also known as a board card, or an adapter card) is circuitry designed to provide expanded capability to a computer. It is provided on the surface of a fiberboard and then plugged into one of the computer's expansion slots in its motherboard. Expansion cards may come in one of two sizes designed to match standard slot dimensions. A card can actually contain the capability within its circuitry (e.g., video card) or it can control, through an extended connection, a device such as a hard disk drive.

Speed versus cost In terms of computer hardware, speed and cost are closely related. The more expensive the hardware the better the performance. For this reason only large corporations, universities and government agencies can afford the most expensive supercomputers. Low–end personal computers can provide adequate performance and still be affordable for most families.

In decreasing order of performance and cost

Tell students to exercise carewhen inserting PCMCIA

cards in their slots.



• Supercomputers

• Mainframes

• Servers

• Personal computers

Analog versusdigital

Computers work with digital signals. Digital signals are signals that fluctuate only between distinct discreet values. Computers use binary digital signals, they can only recognize a 1 or a 0. No other values, for example 0.5, 2, etc., are recognized. The main advantage of a digital signal is that it is resistant to errors. Any loss of signal, say a 1 falling to a 0.9, will just be rounded back up to a 1.

Analog signals are signals that have continuous, non–broken, values. If an analog signal represents a 0 and then changes to represent a 2, the signal will take on each value in between 0 and 2. At some point it will be 0.3, 0.7895, 1.78, etc. Computers cannot process analog signals directly, but many common signals, music and voice for example, are analog. Because of this analog to digital conversion is common. For example, your voice is an analog signal. When you talk into a phone it is converted into a digital signal so the computerized network can process it. The digital signal is again converted into analog when your voice is played through a speaker on the other end.





Exercise one Write below what “I/O” stands for.

Exercise two What numerical system do computers use to manipulate and store data?

1 The decimal system

2 The binary system

3 None of the above

Exercise three How many bits does it take to make a byte?

1 Two

2 Eight

3 Ten

4 Sixty

Exercise four Write below what “CPU” stands for.

Exercise five Everything else being equal, which one of the CPUs below is the fastest one?

1 Intel 80386

2 Intel 80286

3 Intel Pentium

4 Intel 80486

Answer—”input/output”.

Answer—Choice 2.

Answer—Choice 2.

Answer—”Centralprocessing unit”.

Answer—Choice 3.



Exercise six Which one of the devices below is an output device?

1 Mouse

2 Keyboard

3 Screen monitor

4 All of the above

Exercise seven List below the two main types of ports used by personal computers.

Exercise eight The primary factor limiting a PC’s data transfer speed is the size of its input/output bus.

1 True

2 False

Exercise nine Through which of the following ports would a laser printer be normally connected to the computer?

1 COM1

2 LPT1

3 COM4

4 None of the above

Exercise ten Which of the problems below was the PCMCIA standard created to solve?

1 The small size of screen monitors in laptop computers

2 The number of incompatible designs for CPUs

3 The lack of a standard for expansion slots in laptop computers

4 None of the above

Answer—Choice 3.

Answer—Parallel and serial.

Answer—True.

Answer—Choice 2.

Answer—Choice 3.



Exercise eleven What is the major difference between a USB port and a Parallel port?

Exercise twelve List below three devices which can be plugged into your computer without you having to tell the computer that a new device is being plugged. Then, name the capability to allow you to perform the above mentioned task.


3 Memoryand storage


• Capacity• CPU cache• RAM• ROM• Diskette drives• Diskettes• Handling diskettes• Formatting disks• Zip disks• Hard disks• CD–ROMs• CD–ROM drives• DVD–ROM drives• Tape drives

Capacity Your computer can store data. Storage capacity is measured in units called bytes, where one byte is equivalent to eight bits. One kilobyte (1K) is equivalent to 1,024 bytes, and one megabyte (1MB) is 1,024 kilobytes or, 1,048,576 bytes—for simplicity, approximately 1,000,000 bytes. As a rule of thumb, you can consider that a letter of the alphabet occupies one byte.

CPU cache Accessing data stored on hard disks is a relatively slow process compared to the speed of the CPU. Because of this, data that is used often is stored temporarily in main memory. Data in main memory can be accessed much faster than data in hard disks but it is still somewhat slow compared to the CPU speed. Therefore, any data that is used often and is already stored in RAM is copied into the fastest type of memory: CPU cache. CPU cache is similar to main memory in that it is volatile and is a type of random access memory. However, CPU cache is embedded into the CPU chip itself.

Remark that graphics take alot of space.

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Being as physically close as possible to the processor has important advantages. The distance, and therefore time, is as short as possible between the processor and memory. The CPU cache doesn't have to compete with any other devices for access to the CPU. Finally, a typical CPU will have between one and three levels of cache with level 1 (L1) being the closest and fastest and level 3 (L3) being the slowest. Cache sizes typically range from 128KB to 2MB or more, with L1 cache being smaller than higher levels.

RAM Aside from the CPU, there are other chips on the motherboard inside your PC. Among these are the chips making up the main memory of the microcomputer. This memory is the main memory, or RAM (for random access memory), or what people refer to as, simply, the memory of the machine.

RAM is the memory used by the computer to store all the data that you enter, as well as the programs that you use. Yet, note that RAM is volatile memory, which means that whatever is stored in it will disappear as soon as the computer is switched off.

A typical PC these days should come equipped with at least 30 MB of RAM. Increasingly, however, PC’s equipped with 64 MB and 128 MB of RAM are becoming more common.

ROM Another type of storage is ROM (read–only memory). Unlike RAM, ROM is not volatile and its contents will remain in memory even when the computer is powered down. The information stored in ROM is electronically built into the physical ROM chips. ROM is the reason that your computer does something when it is turned on. ROM usually contains instructions to perform initial diagnostic functions and then continue with other booting (startup) instructions. The computer may read instructions from ROM but no data may be stored in (written to) ROM. This is the reason why this type of memory is called read–only memory.

Diskette drives As we said before, the main memory of the computer (RAM) is volatile—as the computer is switched off, all information in RAM disappears. Since you would like to keep the data that you create (letters, tables, graphics, etc.), you must store them on disks before it disappears from the main memory.

Indicate that, everything elsebeing equal, more RAM

results in a higher speed.

Warn students that usersnormally should not tamper

with the PC’s ROM.

Say that one diskette drive isnormally enough for most

PCs.

Page 22 • 3 Memory and storage


Diskette drives are the devices where diskettes are inserted so that information can be stored (saved) in them. Disk drives are identified by labeling them as A:, B:, etc.

Normally, the first diskette drive (if you have two, normally the one above or the one on the left) is drive A:, and the second one is B:. A typical microcomputer system has at least one diskette drive.

Diskettes A diskette is a storage medium where you can record your programs and data. PCs nowadays are normally equipped with disk drives that use 3.5" high–density double–sided diskettes that can store up to 1.44 MB of data.

The table below summarizes the different types of diskettes that may be encountered, depending on how recent or old the computer system is.

Handling diskettes Although diskettes are somewhat sturdy, they must be handled with a certain amount of care. For instance, they should not be brought close to strong magnetic fields (e.g., those produced by a TV set, VCR, and telephone units) or placed in warm places (e.g., on your car dashboard on a hot sunny day). Doing so increases the risk of losing the data stored in them.

New users are always concerned with transporting their disks while travelling. Generally speaking, disks should be packed with care and not near any magnetic field (portable telephones, etc.). Disks can be processed through airport security scanners without apparent damage, but, as a standard precaution, disks should be handed over to airport security scanner attendants and a request should be made that the disks not be sent through the luggage scanner. Better safe than sorry.

Indicate that 5.25” disketteshave fallen into disuse.

Size Disk side usability Density Capacity Status

3.5” Double–sided High 1.44 MB Current

3.5 Double–sided Standard 720 K Discontinued

5.25” Double–sided High 1.2 MB Discontinued

5.25” Double–Sided Standard 360 K Discontinued

Warn students thatmishandling of diskettes canresult in the loss of valuable

data.

3 Memory and storage • Page 23


When inserting a diskette in a drive, push it gently until it locks into place. If inserted the wrong way (e.g., upside down), the diskette will not go into the drive.

To remove a diskette from a diskette drive, press the eject button located on the computer to the left or right of the diskette drive.

Formatting disks Different types of disks, but mainly diskettes and hard disks, need to be formatted before they can be used.Different operating systems require the files on a disk to be organized in different ways.

Formatting a disk prepares the disk to store information in various ways expected by operating systems.

Bear in mind, however, that formatting a disk will completely erase all of the contents of the disk and the information lost will not be recoverable. Only format a disk if you have a backup of all your data.

Each method of storing data is called a file system. Some common file systems are

• FAT (Windows)

• NTFS (Windows)

• EXT3 (Linux)

• REISER (Linux)

In general, the various file systems are not compatible with each other. However, most modern operating systems are capable of reading multiple file systems. Still, care must be taken when formatting disks to ensure that all your data will be compatible.

Zip disks A Zip disk is a storage medium, similar to regular diskettes, on which you can record your programs and data on a magnetic tape. The main difference between diskettes and Zip disks is the storage capacity. Various models of Zip disks can hold 100MB, 350MB or 750MB.

Zip disks have the same practical limitations as all magnetic tape disks. They should not be

• brought near magnetic fields

• stored in very hot or very cold places, or in direct sunlight



• brought through airport security scanners

When inserting a Zip disk in a drive, push it gently until the drive pulls the disk. If inserted the wrong way (for example, upside down), the disk will not go into the drive.

Finally, to remove a Zip disk from a Zip drive, press the eject button located to the left, right or below the Zip drive.

Hard disks A hard disk is basically the same thing as a diskette, but it can store more data (500 MB, 800 MB, 1.3 GB, 3 GB, 30 GB, 40 GB etc.). A hard disk is a single unit with the drive containing it (i.e., the hard disk is not inserted or removed from its drive). The hard disk drive is normally drive C:. A microcomputer normally has one hard disk.

In a local area network, the different workstations may be sharing a centralized hard disk of high capacity (10 or 40 GB, etc.). In a network, the centralized hard disk in the server is usually drive F:.

The speed of the hard disk primarily depends on its access time. Each hard disk has an access time that indicates how long it takes to access information.

CD–ROMs A CD–ROM is a compact disk (CD) into which data has been saved (normally by the manufacturer) but into which you (the user) cannot save. That is, CD–ROMs are disks from which data can be retrieved (i.e., from which data can be read), but into which no data can be saved (i.e., into which data cannot be written). Atypical CD–ROM can store approximately up to 650 MB’s.

Colloquially, CD–ROMs contain memorized data that can only be read. This is why they are referred to as compact disks with read–only memory (CD–ROM). Thus, the CD–ROMs

State that the PC may beginto malfunction if the hard

disk is close to becoming full.

Tell students to exercise carewhen handling CD–ROMs.



available in the market contain information which users want to retrieve but which they normally do not want to alter. For example, dictionaries, thesauri, encyclopedias, maps, movie listings with movie clips, magazines and many others are sold in CD–ROM format. The advantage that CD–ROMs have over traditional books or magazines is that they can contain not only text or pictures, but also sound and video.

CD–ROM drives are the drives into which CD–ROMs are inserted. They are also designated by a letter followed by a colon (e.g., D:, E:, etc.).

CDs are a type of optical storage media, as opposed to the magnetic storage media, such as diskettes. Information on a CD is written and read through a laser beam. Data storage consists of millions of indentations burnt into a reflective metallic surface. CDs have a number of advantages over diskettes. For example, a CDs capacity ranges up to 6 gigabytes; (six billion bytes compared to the 1.44 megabytes (MgB) of the diskette. One CD holds the equivalent of 500 diskettes worth of data. Furthermore, CDs last up to seven times longer than diskettes.

CD–ROM drives CD–ROM drives are the drives where CD–ROMs are inserted so that the information contained in them can be read into the computer system. Software such as complex games require that the CD–ROM containing the program or accompanying data files be left in the CD–ROM drive while using the software.

Today, there are different types of CD–ROM drives that allow different capabilities, as shown below.

Comment that 12x speed CD–ROM drives are standard.

Drive Type Read And Write Capability

CD–ROM drive (Compact Disk–Read Only Memory

Reads audio CD, CD–ROM, CD–R, Photo CD

CD–ROM multiread drive (Compact Disk–Read Only Memory, Multi-read)

CD–ROM, CD–R, CD–RW, CD–i, Photo CD

CD–R drive (Compact Disk–Recordable)

Reads CD–ROM and CD–R, some read CD–RW (Writes once on CD–R disks)

CD–RW drive (Compact disc Rewritable)

Reads CD–ROM, CD–R, and CD–RW (Writes and rewrites on CD–RW disks)

DVD–RAM (Digital Versatile disc – Random–Access–Memory)

Reads all CD formats. Reads DVD ROM. Reads and writes DVD disks



DVD–ROM drives A DVD–ROM drive is basically the same as a CD–ROM drive with only a few differences. A DVD–ROM drive has two lenses on its swivel; one to read the CD–ROM layers, and one to read DVD–ROM layers. The data on a DVD–ROM is in the middle of the disc thickness, in order to accommodate double–sided disks, and the data on a CD–ROM is near the surface of the CD–ROM disk. Hence, a DVD–ROM drive can read both CD–ROMs and DVD–ROMs. Another difference between a DVD–ROM drive and a CD–ROM drive is the revolutions per minute (RPM) value. Even though DVD–ROM drives have a much lower RPM value than a CD–ROM drive, data transfer rates are much higher than a CD–ROM drive at equivalent revolutions per minute (RPM). This is the case due to the fact that the data is compressed by the use of a greater number of smaller data pits and a smaller track pitch (the distance between tracks). For example, a 1X DVD–ROM drive transfers data at 1,250 KBps, whereas a 1X CD–ROM drive transfers data at only 150 KBps.

Tape drives Tape drives, and their associated data cartridges, are high capacity, long term storage media. Tape drive data cartridges can have a capacity of hundreds of gigabytes. The tape drive is housed inside a computer, like CD–ROMs and diskette drives, and the data cartridges are inserted into it.

Tape drive data cartridges were developed from Digital Audio Tapes (DAT) and can either resemble an audiocassette or a small rectangular cartridge. They are ideal for backup purposes because of their high capacity, but even more because of their reliability. Data cartridges can last for many years without becoming corrupted or damaged.

There are two major disadvantages of tape drives

• files must be accessed sequentially; to get to a file on the middle of the tape, the tape must be "fast forwarded" to that point

• compared to hard disks or other large storage media, tape drives are very slow

These downsides are mostly irrelevant when used in long term data storage.





Exercise one 1 byte is exactly equivalent to

1 12 bits

2 10 bits

3 8 bits

4 1,024 bits

Exercise two 1 kilobyte is exactly equivalent to:

1 1,000 bytes

2 1,024 bytes

3 1 million bytes

4 None of the above

Exercise three 10 megabytes are exactly equivalent to:

1 10 million bytes

2 1,048,576 bytes

3 10,485,760 bytes

4 10,048,576 bytes

Answer—Choice 3.

Answer—Choice 2.

Answer—Choice 3.



Exercise four Write below what “RAM” stands for.

Exercise five Write below what “ROM” stands for.

Exercise six When the PC is turned off, the data (i.e., the documents, worksheets, graphics, etc.) stored in RAM are lost.

1 True

2 False

Exercise seven What is the storage capacity of a double–sided, high–density, 3.5” diskette?

1 1.44 MB

2 360 KB

3 650 MB

4 1,024 bytes

Exercise eight How is the hard disk normally labelled in a standard PC?

1 B:

2 C:

3 F:

4 A:

5 None of the above

Answer—”Random accessmemory”.

Answer—”Read–onlymemory”.

Answer—True.

Answer—Choice 1.

Answer—Choice 2.



Exercise nine A hard disk’s access time indicates:

1 The storage capacity of the hard disk

2 The amount of RAM the PC has

3 The speed of the hard disk

4 None of the above

Exercise ten How much data can a typical CD–ROM approximately store?

1 10 MB

2 100 GB

3 1.44 MB

4 650 MB

Exercise eleven What is the major difference (s) between a CD–ROM drive and a DVD–drive? Name two differences.

Answer—Choice 3.

Answer—Choice 4.


4 Peripheraldevices


• Screen monitor• Keyboard• Mouse• Trackball• Lightpens• Printers• Plotters• Modems• Scanners• Joysticks• Touch–screen technology• Digital cameras• Cameras• Microphones• Speakers

Screen monitor The screen monitor, among other things, allows you to see what you type. It is the standard form of output. Older monitors (e.g., those used during the 1970’s) could display only monochrome text, not colors or graphics. Today, standard monitors are color graphics monitors, which can display both text and graphics in up to several million colors. Some examples of graphics monitors are EGA (Extended Graphics Array), VGA (Video Graphics

Indicate that, like in the caseof TV sets, some monitors are

better than others.

Page 31


Array) or SVGA (Super Video Graphics Array). Today, SVGA color graphic monitors are standard.

Monitors have characteristics like interlacing or non–interlacing, dot–pitch resolution and refresh rate. The electron beam in a computer monitor paints the screen at least 6 times per second; else, the human eye will probably detect flicker. Some video systems tried to achieve a higher screen resolution—sharper images—by a mechanism known as interlacing which actually involved retracing the screen at a rate of 43 times per second. When exposed to interlaced monitors, some users have a tendency to develop eyestrain headaches. Thus, when purchasing a high–resolution video system (such as 1024 x 768) check that it is non–interlaced.

The most common monitor sizes are and 15”, although 17” monitors are becoming more common. Many manufacturers also offer large 21” monitors. The latest monitors in the market, today, are the Flat Panel LCD monitors. These monitors are thin and compact. LCD monitors provide the best picture quality, and use less power than the standard VGA monitors. Furthermore, the viewable area of a Flat Panel LCD monitor is the same as its

Page 32 • 4 Peripheral devices


specified size. That is, a 15” LCD monitor has a viewable area of 15” which is not the case in the standard monitors.

Keyboard The keyboard is the standard device for sending information into your computer system. It looks and works pretty much like a typewriter keyboard. (It has the letters of the alphabet, the Shift keys can be used to type in upper case, etc.)

The keyboard also has additional keys such as Ctrl (Control), Alt (Alternate) and ESC (Escape). These keys are known as constraint keys (or control keys) and their purpose varies depending on the software being used at the time. For example, if you are in Excel for Windows, pressing the key F1 while holding down the Alt key creates a chart sheet, whereas if you are in Wordperfect for DOS (an older version of WordPerfect), it invokes the thesaurus that comes with the program. Programs that have been designed to run under Windows 98, Windows 95 or Windows NT Workstation share many of these key combinations. For example, in many Windows programs, pressing S while holding down the Ctrl key saves the current file.

Let students know that thereare keyboards with different

ergonomic designs available.

4 Peripheral devices • Page 33


Some keyboards are cordless, and are equipped with Internet Hot Keys allowing quick access to the Internet with a touch of a key.

Mouse A mouse is a pointing device that allows you to execute commands by pointing and clicking, instead of typing. Most programs require the use of a mouse. For example, sophisticated programs such as Excel and Word for Windows are used with a mouse, whereas, “simple” in–house “utility” programs such as those used by airport ticket agents are normally used with only the keyboard.

You can operate Windows–based programs using keyboard commands, but generally this method is limiting and inconvenient.

Trackball A trackball is a device similar to a mouse in that it allows you to execute commands by pointing and clicking, instead of typing. A trackball contains a ball embedded in a socket that can be rotated, the rotation of the ball moves the pointer on the screen. Buttons on the trackball serve the same purpose as those on the mouse and are typically clicked with the thumb.

Remark that mice come intheir standard form, but also

as track balls, miniature micefor palmtops, etc.



Trackballs are not as common as they once were and are now typically used in more specialized applications. They are for example embedded into public terminals, used in air traffic control, submarines, and arcade games.

Lightpens A lightpen is a pointing device similar in looks to a regular ink pen. There are two types of lightpens:

• Those that are light sensitive and can be used directly on a CRT monitor, similar to a touchpad (they cannot, however, be used on LCD, plasma or other monitors)

• And those that are used on a specialized pad and can be used like a mouse

Lightpens are often used by artists to create digital images. Because most artists are used to drawing on paper with a pencil, paintbrush, etc., it can be awkward to draw with a mouse. Lightpens solve this problem because they can be held and used just like an ink pen.



Printers A printer allows you to obtain a hard copy (i.e. on paper) of your work. There are three main types of printers for PC use: dot–matrix printers, inkjet printers and laser printers.

If you look carefully at the printout produced by a dot–matrix printer you will notice that the characters are made up of little dots. The term “matrix” comes from the fact that the head of the printer (which prints the characters on the paper) is a matrix of pins. Which pins get fired depends on the shape of the symbol being printed. Dot–matrix printers can print both text and graphics. The quality of their output has improved dramatically.

Inkjet printers are quiet and produce a better quality print than dot–matrix printers. The inkjet is a derivative of the dot–matrix in that it sprays ink dots onto the page. Because of their low cost, high quality and versatility, high–resolution color inkjet printers are now quite common among home users.

State that the price of laserprinters has come down

considerably to make themaffordable to many home

users.



In business, most offices use laser printers because they offer fast, high–resolution printed output for both text and graphics.

Plotters A plotter is a specialized type of printing device that allows you to produce a hard copy of a document. Plotters do not "spray" ink onto paper like an inkjet printer, instead, a pen "draws" out an image onto paper just as a person would draw a picture.

Plotters are no longer used in the home or office because they are very slow compared to inkjet and laser printers.

Plotters excel at drawing lines and are generally used when intricate line drawings are required such as Computer Aided Design (CAD) drawings, technical drawings, and blueprints.



Modems You can send and receive data over short and long distances with your computer if you connect it to a modem that in turn connects to the telephone line. For example, if your PC is equipped with a modem, and you have the appropriate software, you can connect to the Internet to browse the pages of information available on the Internet’s World Wide Web, send and receive electronic mail, etc. Also, with a modem–equipped computer, you can work with a server in, say, Vancouver or Toronto as if it were sitting on your desk.

Before you can use a modem to transmit information you have to get first a telecommunications software package. A computer program of this type will allow you to interact with your remote station through your modem. Special parameters, besides the telephone number you are dialing, need to be set in your modem before a successful telecommunications session can take place. These are the baud rate (the speed at which signals are to travel), the parity (for data loss checks) and the duplex (to confirm data reception).

An internal modem comes in the shape of a card that plugs directly into a specific slot in your computer’s motherboard (the printed circuit board where the CPU, RAM chips, etc. are plugged). An external modem is connected to the computer via a cable and port.

Suggest to students that forInternet use, a high–speed

modem is recommended.



Scanners Scanners are devices that allow you to take printed information (e.g., photographs) and convert them into digital data that can then be manipulated with computer software. That is, as a printer is used to take digital information and output it on paper, a scanner is used to take information on paper and input it into a computer system.

A flatbed scanner looks and is operated like a small photocopying machine—the page of printed information to be scanned is placed on the scanner bed, the cover is lowered, and it is scanned into the computer system to which the scanner is attached.

Joysticks Joysticks are devices used to replace the mouse and keyboard when playing computer games. Current joysticks allow you not only to control the movement of objects on the screen (e.g., of spaceships) but also come equipped with triggers to execute commands (e.g., shoot down enemy spacecraft). With some of them the user can even feel the effect of recoil when shooting.

Touch–screentechnology

Aside from the keyboard and the mouse, sophisticated systems can be built which use touch–screen technology (Touchpad) to send information into your computer system. For example, a

Remark that, although lessexpensive, hand–held

scanners require a ”steadyhand” when using them.



point–of–sale system can be designed in such a way that the cashier operator touches buttons which appear on the screen in order to carry out all point–of–sale operations at a store.

Digital cameras A digital camera records and stores photographic images in digital format as JPEG, TIFF, and MPEG file types that can be transferred to a computer as the impressions are recorded. Alternatively, the image can be stored in the camera and can be loaded into a computer later on. For example, you can go on a long vacation and take pictures as you would normally do with a regular camera. Once you are back at your computer you can load your vacation images into your computer and view or print them.

To retrieve photographs from a digital camera it must be plugged into a computer with the necessary software installed. This is usually done through a USB cable on a Windows based computer or through a FireWire cable on a Macintosh based computer.

The number of pictures that a digital camera can hold is dependent on two factors:

• size of the memory card inside the camera

• number of Mega Pixels the camera can support, or put another way, the resolution of the final image

Digital cameras use compact flash memory cards to store pictures (1GB compact flash memory card).The larger the storage capacity of the flash card the more pictures can be stored. Sizes of flash memory range from 16MB up to 2GB or more.

The term "pixel" is an abbreviation for "picture element". A digital picture is composed of a number of dots grouped together to form an image. Each dot is called a pixel. When a camera claims to be, for example, 3.2 Mega Pixels, it simply means that each picture can contain up to 3.2 million pixels. The more pixels that an image contains, the sharper and cleaner it will be. However, more pixels use up more storage space. A 2.1 Mega Pixel camera, creating images with dimensions of 1600 by 1200 pixels, is considered the minimum requirement to produce a good quality 8X10 print.



Creating prints from a digital camera can either be done by using a high quality color printer and photo paper or by taking the flash memory card to a photography store that can process digital images.

Cameras Web cams, video, or homecams are attached to a computer whose current or latest image is being projected through a Web site or from one computer to another. Web cams are being used to hold live meetings or telephone conversations allowing users to be able to see each other (providing both users have a Web cam attached to their computers). In many Web sites, today, we can see Web cams projecting a live view of whatever the Web cam is pointing at. The Web cams in the market, today, offer the capability of sending live photos, and videos.

Microphones A microphone is a device that records sounds. On a computer, a microphone is typically plugged into a sound card. Microphones are useful when combined with a computer because of the abundance of easy to use audio editing software.



Audio editing software has many features including adjusting the volume, filtering out noise, changing the pitch and tone and splicing together multiple sound files.

Speakers Speakers output sound and are used in computers to play sounds from the operating system, (e.g., a beep indicating an error), music, audio in movies, voice in a slide presentation, sound from video games etc.

Speaker systems specifically made for computers are readily available. These systems will have from two to five individual speakers and can be plugged directly into a sound card.

Speaker cable connected to sound card.

Conventional speakers can be connected to a computer through an audio receiver capable of digital to analog conversion.





Exercise one Which of the following is not a standard PC screen monitor size?

1 14”

2 15”

3 16”

4 17”

Exercise two The function of the Alt and Ctrl keys varies depending on the program being used.

1 True

2 False

Exercise three What type of device is a mouse?

1 A pointing device

2 A storage device

3 A processing device

4 None of the above

Answer—Choice 3.

Answer—True.

Answer—Choice 1.



Exercise four List below the main three types of printers.

Exercise five With the help of a modem you can:

1 Connect to the Internet to browse the World Wide Web

2 Connect to the Internet to send and receive electronic mail

3 Control a computer remotely

4 All of the above

Exercise six Briefly describe below the purpose of a scanner.

Exercise seven List below the main two types of scanners available.

Exercise eight What are joysticks mainly used for?

Answer—Dot–matrix, inkjetand laser.

Answer—Choice 4.

Answer—To take informationon paper and input it into a

computer system.

Answer—Hand–held andflatbed.

Answer—To replace themouse and keyboard when

playing computer games.



Exercise nine List below four different multimedia hardware devices.

Exercise ten Touch–screen technology can be used under some circumstances to replace:

1 The screen monitor

2 Speakers

3 The mouse and keyboard

4 All of the above

Exercise eleven What does a Personal Digital Assistant (PDA) allow you to do? And how does it differ from a desktop or laptop? (Name two major differences).

Exercise twelve Name two ways in which you can access e–mail and the Internet using a Personal Digital Assistant (PDA).

Answer—For example, anyfour of: sound cards,

speakers, microphones,digital photographic

cameras, video cameras.

Answer—Choice 3.



Exercise thirteen Name two ways in which a Web cam is used in today’s markets.


5 Networkbasics


• Information technology• Networks• LANs and WANs• Wireless LAN• Reasons for networks• Workstations• Servers• Client / server architecture• Nodes• Domains• Network interface cards• Cabling• Network connectors• Telephone networks in computing• Local vs. shared devices• Shared drives• Teleworking

Informationtechnology

Large networks with hundreds or thousands of computers, such as those found in businesses, schools, hospitals and government offices, can be difficult to maintain.

Hardware fails over time; main memory may become corrupted, a hard disk might fail or a mouse can break. All of these things must be fixed in a timely manner or worker productivity will suffer.

Operating systems slow down, or even fail, as more programs are installed. Programs themselves can become obsolete and need to be updated. These things must also be taken care of.

Typically an Information Technology (IT) department is used to install and maintain the network of computers. The IT department will respond to users to fix hardware and software problems as well as upgrade and install new components. The IT department can also enforce a company's security and usage policies.

Page 47


Networks A computer network is a group of computers that have been interconnected with one another for the purposes of sharing data or devices.

A network can be as simple as two desktop PCs sharing a printer or as complex as several hundred or even thousands of machines, some of which could be notebooks, desktop PCs, minicomputers, mainframes or supercomputers.

LANs and WANs Like most things in life, networks come in sizes. Local area networks (LANs) are networks that reside within a limited area. For example, within a single office, or multiple offices within a city, or within a province–wide company.

Wide area networks (WANs), on the other hand, connect LANs over large geographical areas as large as a whole country (national networks) or around the globe (international networks). A WAN may include more than one organization (e.g., several universities, hospitals, government agencies, etc.).

Remark that networksappeared after personal

computers were available.

Indicate that LANs havebecome widespread in

corporations of all sizes.

Page 48 • 5 Network basics


Wireless LAN A wireless LAN is one in which a user can connect to a local area network (LAN) through a wireless connection.

Using technology from the different manufacturers, a wireless LAN adapter can be made to fit on a Personal Computer Memory Card Industry Association (PCMCIA) card for a laptop or notebook computer.

Reasons fornetworks

Sharing is the main reason for networking computers. For instance, if you work in an office where there are twenty PCs and everybody has the need to print, there is no need to purchase twenty printers and attach them to each PC individually. Instead, all users could share two or three printers if they are properly networked.

A second important reason to network computers is so that users can conveniently share data stored at a central location.

A third reason is so that employees can send one another messages via electronic mail over the network as opposed to using e–mail services over the Internet which is less secure.

5 Network basics • Page 49


Workstations Workstations are the desktop PCs in the network that users do their daily work with. Workstations in the LAN perform a large fraction of work done on the network and this accounts for much of the popularity of LANs.

Depending on the applications the users work with in a network, one could safely say that the LANs performance does not degrade much as the number of users increases.

The main difference between a PC which is part of a LAN and one which is not is that it has a special piece of circuitry—a network interface card—to connect the PC to the LAN and some special (network) software.

Also, it is important to note that in a LAN or WAN the workstations are normally computers in their own right, as opposed to mere “dumb” terminals. That is, in a network, usually each workstation has a CPU and thus has its own computing power. In a minicomputer or mainframe model with tens, hundreds or thousands of terminals, the terminals do not have a CPU of their own—all the computing power resides in the main computer (the minicomputer or mainframe) to which the terminals are connected. This means that in a minicomputer or mainframe model, the computing power is shared among all the terminals in use, which means that the more terminals are in use, the less power is available to each. In a network, on the other hand, the processing done at the workstation level by the workstation’s own CPU is independent of whether other workstations are in use or not. Thus, its computing power remains largely unaffected by the activity or inactivity of the rest of the workstations in the network.

Servers As their name indicates, servers are computers which serve the needs of the workstations in the network.

There are different kinds of servers. File servers, for instance, store data files that are shared among the users in the network.

Print servers, on the other hand, control printers and the print jobs sent to them. It is not unusual for a server to act as both a file server and a print server.

A communications server allows several users in the network to engage in simultaneous telecommunication sessions with remote computer systems.

Today, most servers are also application servers. Their purpose is to run applications that can be shared simultaneously by many users in the network. The application actually runs on the server itself; the user’s PC just runs a “front–end” to the application. For example, a database management system used to store and manage information records can be

Make sure that studentsunderstand that in a network

each workstation is acomputer in its own right, as

opposed to a mere dumbterminal.

Make sure that studentsunderstand that different

kinds of servers fulfilldifferent needs.



accessed by users for the purpose of processing information in many powerful ways and with relative ease. The database program runs on the server computer and the data it manages is made available to the users via “data forms” or “report generators” running on their PCs.

Client / serverarchitecture

The client/server architecture is a scheme for supplying services to users. In a client/server system the server provides some sort of service to clients. Clients in turn connect to the server in order to make use of the service.

Clients are typically end users, whereas servers are typically computer servers or a network of computer servers in some remote location relative to the clients.

Some uses and examples of client/server systems

• logging into a corporate directory on an Intranet to find a phone number

• Web browsers, like Internet Explorer, allow users (clients) to connect to Web pages (on servers)

• requesting the current time from a time server to update the clock on your PC

Nodes A workstation, server or printer attached to a network is called a node. That is, the nodes in a network can be notebooks, desktop PCs, printers, mainframes, etc.

Domains A domain is a collection of computers and other network resources, such as printers or modems. Domains greatly simplify network account management and add flexibility to the network. For instance, if you need to access two different servers there is no need to supply two accounts and two passwords. Instead, you need to do it only once for the domain they belong to.

Network interfacecards

Every PC that is part of a network has a network interface card (NIC). An NIC is a board with specialized chips that sits inside of the computer and has a jack connector where the

Remark that Windows NTServer has sophisticated

domain capabilities.

Remark that, in notebooks,NICs are PCMCIA cards.



network cable is plugged into. This allows the PC to be connected to the rest of the network.

Cabling Although different networks use different types of cables to interconnect the computers in the network, two have become standard—twisted pair cable and coaxial cable.

Twisted pair cable looks like the cable that runs from your phone set into the telephone jack on the wall.

Twisted pair is rather inexpensive and very malleable. However, it does not insulate signals from electromagnetic interference as effectively as coaxial cable (which looks like your TV cable). On the other hand, coaxial cable is more expensive than twisted pair cable and does not bend easily over sharp corners, which calls for a more difficult installation.

Fiber optic cable is a third type of cable—it is expensive but extremely reliable and very fast at signal propagation.

Network connectors The PCs NIC is connected to the rest of the network by running a cable from it to a jack on the wall.

Telephone networksin computing

The public telephone network is used widely in computing. The entire global telephone network is called the Public Switched Telephone Network (PSTN). A popular method of connecting to the Internet is through a telephone line. However, there are some downsides to using the telephone to connect to the Internet

Indicate that wirelessnetworks are becoming more

popular as the technologyimproves.



• it has fairly slow transfer speeds, the fastest modems have a baud rate, or transfer rate, of 56,000 bits per second

• connecting to the Internet ties up the phone line, so it is not possible to talk on the phone while connected to the Internet if only one line is available

Because of these downsides other methods of connecting to the Internet have been created. One popular method is through the cable television network.

However, high speed connections through the telephone line have also been developed. Integrated Services Digital Network (ISDN) is a network built on the existing telephone line that is optimized for digital data transfer as opposed to voice transmissions. Basic ISDN lines have a transfer rate of about 150 thousand bits per second. However, multiple lines can be joined together to achieve speeds of up to 1.5 million bits per second (called a T1 line).

Asymmetric Digital Subscriber Line (ADSL) is a common type of high speed Internet connection. The network uses the traditional phone line but can achieve must faster speeds. The speed of the connection is dependent on how close the user is to the main switching center: speeds range from 256 thousand bits per second to 8 million bits per second.

Local vs. shareddevices

Any device attached to a PC for the sole use of the user working on that machine is called a local device.

Any device attached to a computer but that is shared by many users is known as a shared device, Typically, shared devices are attached to servers but, in rare cases, can also be connected to workstations.

An example of a local device is the keyboard attached to your PC since nobody, but you, can use it at any given time. Your PC’s floppy drive is also an example of a local device.

The hard disk in a file server, on the other hand, is an example of a shared device since many people on the network use it.

To be sure, servers have local devices too that only the person operating the server (e.g., a member of the technical support staff during a maintenance session) can operate.

Printers are devices that can be either local or shared.

Shared drives Shared drives are a common example of a shared device. Network software can make a disk on a computer, such as a server, accessible from another computer such as your PC.

The network software makes your PC believe that the disk (that is actually in the server) is attached to the PC. That is why these disks are sometimes called "virtual" disks. The PC believes something is true—namely, that it has a new extra local drive—when, in fact, it is not true (since the drive is somewhere else).

State that one of the mainreasons for share devices is

cost savings.

State that sharing drivesallows users to exchange

data easily.



If your PC has a hard disk drive labeled C: then a network disk would use up the next letter in the alphabet, D. By convention, in many network PCs, the drives F: though Z: are also used to label network drives.

Teleworking Teleworking is a term used to define someone who works remotely from their home.

There are many advantages to working from home, for both the employee and the employer, as well as disadvantages.

Some of the advantages are that workers do not have to commute from home to work, physically disabled workers can be easily accommodated and less need for office space.

However, there are some disadvantages. It can be harder to organize projects, teamwork may suffer and there may be reduced camaraderie amongst employees.



Exercise one Write below what “WAN” stands for.Answer—”Wide area

network”.



Exercise two Write below what “LAN” stands for.

Exercise three Briefly describe below what a computer network is.

Exercise four List below two types of cable used in networks.

Exercise five Which of the following devices is normally a shared device in a network?

1 Screen monitor

2 Printer

3 Mouse

4 Keyboard

5 None of the above

Answer—”Local areanetwork”.

Answer—A computer networkis a group of computers that

have been interconnectedwith one another for the

purposes of sharing data ordevices.

Answer—Any two of: twistedpair, coaxial, fiber optic.

Answer—Choice 2.



Exercise six Application servers are quite common in networks. List below three other different kinds of servers used in networks.

Exercise seven What kinds of computers can be part of a network?

1 Supercomputers

2 Desktop PCs

3 Minicomputers

4 Notebooks

5 Mainframes

6 All of the above

Exercise eight A computer attached to a network, whether a workstation or a server, is called a node.

1 True

2 False

Exercise nine A domain is a collection of computers and other network resources, such as printers or modems.

1 True

2 False

Exercise ten Briefly write below what the purpose of a Network Interface Card (NIC) is.

Answer—File servers, printservers, communications

servers.

Answer—Choice 6.

Answer—True.

Answer—True.

Answer—To connect a PC toa network.






6 Operatingsystems


• Software and data files• File names and extensions• Purpose of operating systems• Running multiple applications• Operating system evolution• DOS• Graphical user interfaces (GUI)• Windows 3.1/3.11• Windows 95• Windows NT Workstation• Windows 2000 Professional• Windows 98• Windows Me• Windows XP• Windows NT Server• Windows 2000 Server• Novell NetWare• Unix• Linux

Software and datafiles

By “software”, normally people mean the programs they use with their computers. However, you should keep in mind that, strictly speaking, the documents, worksheets, graphics, etc. one creates with programs are also software, though they are normally referred to “data files” or simply as “data”.

To keep them for repeated use, both programs and data are stored on disk as files. That is, when you purchase a computer program (e.g., a wordprocessing program like Word or a spreadsheet program like Excel), you are in fact purchasing a set of files (program files). Likewise, when you create, say, a business letter with a wordprocessing program and save it on a disk for future use, the business letter is saved as a file (a data file).

Stress that, in general, datafiles are far more important

than programs.

Page 59


As time goes by, your disks may end up containing a multitude of program files (that you have been purchasing) and data files (that you have been creating). As the number of files grows rapidly, it is very easy to forget where they are located, or to lose track of how up–to–date data files are, etc. This is why disks are normally organized into folders (formerly known as directories) that contain program files or data files or other sub–folders (sub–directories) for further organization, as shown in the diagram depicted below.

It is important to make backup copies of your data files—sooner or later files are deleted by accident, become corrupted or otherwise lost. Remember, if you lose a program, you can re–install it or, in the worst case, you can purchase it again. But if you lose a data file for which you do not have a backup copy and you want it, it has to be re–created anew. Again, if the data file is a simple one–page letter, it may take little time to re–create it, but if it is a database with all the information about the customers of a company, the company may go out of business if its customer database is lost.

File names andextensions

Program files and data files saved on disk are identified by their filenames. The filename of a file consists of the name proper plus an optional extension. The file name and the file extension (if any) are separated by a period. For example, a business letter may have the filename Bank.doc, whereas an invoice may have a filename like, say, May Invoice.xls.

Files acquire their filenames normally when they are saved for the first time. For example, if you type a letter with a wordprocessing program like Word and save it, the program will ask you to supply a name for the file (e.g., Bank.doc). In most cases, the user supplies the name of the file whereas the program used to create it automatically supplies the extension. That is, if you save a document created with Word with the name Bank, Word will automatically add the extension (separated by a period) doc, so that the resulting file ends up with the filename Bank.doc in the disk. Different programs give different extensions to the files created with them. For instance, Excel adds the extension xls (for “Excel sheet”), WordPerfect for Windows adds the extension wpd (for “WordPerfect document”), PowerPoint adds the extension ppt, etc.

Thus, since most programs add an extension automatically to the data files created with them, you should normally not add an extension when saving a file. A program may not be able to open a file with an extension which it does not recognize.

Extensions are useful because they allow you to identify what type of files you have on disk. For example, if you see a file called, say, Bank.doc, chances are that such a file was created with Word and, if you want to read it, you need to open it with Word and not with Paint.

Wordword.exe (file)

normal.dot (file)

Excelexcel.exe (file)lookup.xla (file)

Powerpntpowerpnt.exe (file)general.pot (file)

Programs

Westbrochure.fm (file)

invite.doc (file)

Centralflyer.doc (file)offer.doc (file)

discount.xls (file)

Marketing

quarter1jan.xls (file)feb.xls (file)mar.xls (file)

quarter2apr.xls (file)may.xls (file)jun.xls (file)

Accounting

Data

C:\

Page 60 • 6 Operating systems


Likewise, if you see a file called, say, Corporate logo.bmp (a bitmap graphic file), you would need a graphics program like Paint to open it. In particular, files with the extension exe (e.g., Word.exe, Excel.exe, etc.) are executable files—that is, they are program files, not data files. When you purchase a computer program like, for example, Excel, you are purchasing, among others, a file called Excel.exe that programers at Microsoft have created.

In the later versions of the Windows operating system (e.g., Windows XP Professional, Windows 2000 Professional, Windows Millennium Edition, Windows 98, etc.), a file or folder name can contain up to 215 characters, including blank spaces. However, bear in mind that most programs cannot work with files with such long names. Also, you should keep the names of your files manageable. In any event, filenames cannot contain the following characters:

\ / : * ? " < > |

The filename of certain system folders—such as Documents and Settings, Winnt or System32—cannot be changed because they are needed for Windows to run properly.

Older operating systems like DOS (or the combination DOS/Windows 3.1) could accept filenames with at most 8 characters plus an extension of three characters, with a period separating the name from the extension (as in MEMO.DOC, LOGO.BMP, etc.), and no blank spaces were allowed.

Therefore, whereas Windows 98 or Windows XP allows filenames such as

West coast business plan.doc

users working with DOS/Windows 3.1 had to use non–intuitive filenames like

WCBUSPLN.DOC

Purpose ofoperating systems

All computers, whether they be PDAs, palmtops, notebooks, desktops, entire computer networks, mainframes or supercomputers, need an operating system (OS).

An operating system is a computer program which regulates and controls the flow of information in your computer system. For example, the operating system controls how data flows from the computer’s memory (RAM) to the hard disk when it is saved by you. Likewise, the operating system is responsible for sending the right data to the printer and not to, say, the diskette drive, when you issue the command to print. Also, an operating system allows you to copy data from one disk to another, to change the names of files in the disk, to delete unwanted files, etc.

Personal computers that use CPUs manufactured by Intel normally use one of the operating systems manufactured by Microsoft—Windows XP, Windows 2000 Professional, Windows 98, etc. Macintosh computers, on the other hand, use one of the operating systems manufactured by Apple specifically for the Macintosh (MacOS).

Local area networks (LANs) also need an operating system to control the flow of information among the different workstations and servers that make up the network. Well–known network operating systems (NOS) include Microsoft Windows 2000 server, Microsoft Windows NT Server, Novell’s NetWare, Unix, Linux, etc.

Indicate that when twocomputers can use the same

operating system, we say thatthey are compatible.

6 Operating systems • Page 61


Running multipleapplications

By definition, a CPU is capable of processing simple logical statements to execute complex computer programs. These statements include adding and subtracting, storing and recalling data to and from memory and evaluating conditions like greater than, less than and equal to. Combined in a logical way, these statements can determine the execution of a computer program. Modern operating systems can handle multiple applications running simultaneously. In that case the CPU will alternate between applications, allowing one to execute statements, then another, then back to the first, and so on. However, the more applications running, the slower each individual application will run since it has to share the CPU.

Operating systemevolution

Over the years, operating systems have evolved, become more powerful, reliable, secure and, in general, more user–friendly. However, being a later operating system does not necessarily mean that it is more powerful or reliable or more secure than all its predecessors. These characteristics depend on the audience for which the operating system is designed. For example, Windows 2000 Professional was released to the market before Windows Millennium Edition (Me), and, yet, because the former was designed for corporate use whereas the later was intended for home users, Windows 2000 Professional remained a more stable and secure operating system than Windows Me.

A historical evolution of the operating systems released by Microsoft for personal computers would include DOS, DOS with Windows 3.1/Windows 3.11, Windows NT Workstation, Windows 95, Windows 2000 Professional, Windows 98, Windows Me, and Windows XP.

DOS MS DOS (for Microsoft disk operating system) was the first popular operating system released by Microsoft. Before it was retired, DOS served the needs of millions of computer users the world over. Among its several functions, DOS allowed the management of your application programs as they were being loaded and executed in the computer. Like any operating system, DOS would reserve memory for their use and for the data they manipulate.

Remark that DOS was a text–based operating system, as

opposed to a graphics–basedone.



DOS’s interface was not graphical, but text–based. This meant that instead of launching programs, copying files, etc. by using a mouse and graphical icons on the screen, users had to type somewhat cryptic messages at a prompt on the screen.

For example, to copy documents from a folder in the hard disk to a disk in drive A:, the user would type a command like

COPY *.DOC A:

Graphical userinterfaces (GUI)

Using a mouse to point and click in a program is done through a graphical user interface (GUI). Historically, programs have been accessed by typing commands into a command prompt. Buttons, icons and menus are used by the user to interface with the operating system or a program in a GUI (typically pronounced "gooey").

GUIs have the advantage of being intuitive and easy to use. However, it can be difficult and time consuming to perform very complex operations with only a GUI. Most operating systems designed for personal computers use a GUI but also provide a command prompt for more difficult operations.



The following illustration depicts some of the components that make up the graphical user interface of Windows XP.

Windows 3.1/3.11 Windows 3.1/3.11 was a computer program (an operating environment) that extended the capabilities of DOS to make one’s PC a more powerful system. For example, since Windows 3.1/3.11 could handle more memory (RAM) than DOS, and could manage it better, users could run larger applications and create more sophisticated documents, worksheets, etc. than they could with DOS alone. Windows 3.1—and its workgroup version 3.11—was not a true operating system—but an operating environment—as it still needed DOS in order to work.

Taskbar Desktop

WindowIcons

Start button

Make clear that DOS was theactual operating system andthat Windows 3.1/3.11 was

the graphical operatingenvironment that runs on top

of DOS. Windows 3.1/3.11needs DOS, but DOS does

not need Windows 3.1/3.11.



One of the reasons why the DOS/Windows 3.1/3.11 combination became so immensely popular was because many people preferred to work with the graphical user interface (GUI) presented by Windows than with the text–only user interface presented by DOS.

For example, with Windows 3.1/3.11, users could carry out commands by selecting them from pull–down menus, or by clicking the mouse and dragging files, without having to type cryptic commands at a screen prompt, as with DOS.

With Windows 3.1/3.11 users could run programs designed to work with Windows 3.1/3.11 as well as programs designed to work with DOS alone. However, soon after Windows 3.1 was released, software publishers ceased to develop new programs for DOS and concentrated in developing for the Windows 3.1/3.11 platform, since this is what users wanted.

Windows 95 Windows 95 was a full–fledged operating system which was more powerful that DOS alone or than the DOS/Windows 3.1/3.11 combination. Aside from being a 32–bit operating system capable of exploiting the more advanced capabilities of the more powerful Intel CPUs (e.g.,

Make clear that Windows 95was a true operating system,

not simply an operatingenvironment like

Windows 3.1/3.11.



Pentium, Pentium II, Pentium III), it also provided a better graphical user interface than that provided by Windows 3.1/3.11.

With Windows 95 users could run programs designed to work with Windows 95, programs designed to work with Windows 3.1/3.11 and programs designed to work with DOS alone. Users the world over relatively quickly upgraded from Windows 3.1/3.11 to Windows 95.

Windows NTWorkstation

Like Windows 95, Windows NT Workstation was another full–fledged 32–bit operating system by Microsoft. Windows NT Workstation would look to the user almost identical to Windows 95. However, it offered better crash protection, multitasking capabilities, network access, security and stability than Windows 95.

Remark that Windows NTWorkstation was intended to

eventually replaceWindows 95 as the standardMicrosoft operating system

for PCs.



Windows 2000Professional

Again a 32–bit operating system and also intended for corporate users, Windows 2000 Professional was released as an improvement upon Windows NT Workstation. People using Windows 2000 Professional enjoy a reliable and stable operating system.

Like Windows NT Workstation before it, Windows 2000 Professional isolates from one another applications which are running simultaneously. Thus, for example, if an application ceases to function properly, it will not affect the rest of the applications currently running. Instead, one can simply shut down the offending application and continue working with the rest.

Though its graphical interface is practically the same as that of Windows 98, Windows 2000 Professional provides better crash protection, multitasking capabilities, network access, security and stability than Windows 98.

Windows 98 Windows 98 was an improved version of Windows 95 which includes, among other features, better integration of Internet capabilities into the operating system and a customizable desktop.

The user interface of Windows 98 remained virtually the same as that of Windows 95.

Remark that Windows 2000Professional was intended to

eventually replaceWindows 95 (and later 98

and Me) as the standardMicrovolts operating system

for PCs.



Windows Me Windows Millennium Edition (Me) was released by Microsoft to enhance the computing experience of home users.

Windows Me came bundled with built–in features to take advantage of advances in digital photography, home video movies, digital music, and to make Internet connectivity easier for the home user.

The interface of Windows Me remained virtually the same as that of Windows 98.

Windows XP Windows XP is the latest incarnation of the Windows operating system. Windows XP is available in two versions:

• Windows XP Professional, intended for corporate users

• Windows XP Home Edition, intended for home users

The Professional edition focuses on capabilities valued by corporations, such as stability, performance and security. Windows XP Home Edition, on the other hand, though a reliable

Remark that Windows XPseeks to replace Windows 95,

98 and Me as the standardMicrovolts operating system

for PCs.



and stable operating system, emphasizes ease of use, shareability, digital photography, music and video, and support services.

The interface of Windows XP is simpler than that of Windows 2000 Professional, 98 or Me. Yet, users familiar with the interface of the later operating systems will have no problem getting used to the one featured by Windows XP.

Windows NT Server Windows NT Server was a powerful and sophisticated network operating system by Microsoft. Like Windows NT Workstation, it used a user interface almost identical to that of Windows 95/98. But again, it offered a number of advanced capabilities and features which pertained to mature network operating systems and which were beyond the scope of even very good operating systems designed for individual personal computers like Windows 98, Windows NT Workstation or Windows 2000 Professional.

Windows NT Server allowed you to set up a network in which Windows NT Server was the network operating system, while Windows 95, Windows 98 or Windows 2000 Workstation, or a combination of these, was the operating system used by the individual workstations (PCs).

Remark that Windows NTServer started to become thestandard network operating

system for corporations.



Windows 2000Server

So to speak, Windows 2000 Server was to Windows NT Server what Windows 2000 Professional was to Windows NT Workstation—an improvement on an already good technology.

Windows 2000 Server retained the same familiar interface used by Windows 95, NT Workstation, 2000 Professional, 98 and Me.

As with Windows NT Server, you could design a network configuration in which Windows 2000 Server was the network operating system, while the operating system used by the individual workstations in the network was, for example, Windows 98 or Windows XP Professional, or both.

Windows 2003Server

Windows 2003 Server is the latest version of Microsoft’s network operating system. It includes significant improvements over its predecessor, Windows 2000 Sever, particularly in the area of security.

Novell NetWare NetWare (now in version 6) is a network operating system by Novell. It is used by departments in large corporations and by medium and small businesses. NetWare 6 offers flexible, sophisticated and expanded file, print, directory, security and management capabilities. The system comes equipped with powerful software tools to maximize the efficient administration and maintenance of networks.

Yet, though once the leading network operating system, NetWare has been losing market share to rival products from Microsoft, first to Windows NT Server, and then to Windows 2000 Server and Windows 2003 Server. Many companies reckon that Microsoft’s product line fits their corporate strategy better.

Unix Unix is a widely used and very powerful network operating system. Aside from being used by many departments in large corporations, universities and government agencies, many of the computers which are Internet servers run Unix as their operating system. A number of organizations, however, are switching from Unix to Windows 2000 Server, as they see that the latter fits their corporate strategy better.

Nevertheless, Unix remains a very powerful, robust, stable and reliable operating system with enterprise–wide capabilities. Companies like IBM and Hewlett–Packard have their own

Remark that Windows 2000Server continued on the

footsteps of NT server to bethe standard networkoperating system for

corporations.

Indicate that NetWare startedto lose ground to

Windows NT Server andcontinued to do likewise with

respect to Windows 2000Server.

Indicate that Unix is losingground to Windows 2000

Server.



version of Unix—IBM AIX and HP–UX, respectively. Depending on the requirements of particular corporate customers, they can offer Unix or Windows 2000 Server as the operating system for the computer systems being sold.

Unix is also the dominant operating system at academic institutions, research centers, military installations and other mission critical environments.

Linux Linux is an operating system which was originally developed in Finland by a Unix expert called Linus Torvald. Linus Torvald released Linux in 1991 as an “open source” system. This means that no one owns the source code of Linux, and that it is free for anyone to use or modify. In fact, thousands of developers the world over are constantly writing code to improve Linux. This free licensing model gives anyone the right to modify Linux’s source code, but then the code must be given away for free or for a small fee to cover the cost of media such as CD–ROMs used to distribute the software.

First received with enthusiasm by individuals with technical background and academics, Linux has been gaining the favor of corporations as a very powerful and reliable operating system.

Linux can be used as an alternative operating system to run on personal computers or on network servers. Companies like RedHat and Novell package and distribute Linux.


Remarks Make sure that copies of any files needed to complete the following exercises have been saved to the folder My Documents (or to some other suitable folder) in your system. Then, use

Remark that Linux is beingoffered and supported bycomputer companies like

IBM and Hewlett–Packard.



the resulting copies in My Documents to complete the exercises whenever required, unless otherwise indicated.

Exercise one Strictly speaking, data files are software. (Circle one.)

1 True

2 False

Exercise two What is the maximum number of characters that a filename can have in Windows 200 Professional? (Circle one.)

1 Eight

2 Eleven

3 Two hundred and fifteen

4 Two hundred and fifty–six

5 None of the above

Exercise three Which of the following does not provide the user with a graphical user interface?

1 Windows XP Home Edition

2 MS DOS

3 Windows 98

4 Windows 2000 Server

Exercise four List below the names of two well–known network operating systems.

Answer—True.

Answer—Choice 3.

Answer—Choice 2.

Answer—Any two of:Windows 2000 Server,

Windows NT Server,NetWare, Unix, Linux.



Exercise five Which of the following operating systems is run as the standard operating system on Macintosh computers?

1 Windows Me

2 Windows XP Professional

3 Windows NT Workstation

4 None of the above

Exercise six List below three features or capabilities in which Windows 2000 Professional is better than Windows 98.

Exercise seven Write below the two editions Windows XP is available in.

Exercise eight What kind of operating system is Windows 2000 Professional? (Circle one.)

1 16–bit

2 32–bit

3 8–bit

4 64–bit

Exercise nine What is the name of Hewlett–Packard’s version of Unix?

1 Linux

2 NetWare

Answer—Choice 4.

Answer—Any three of: crashprotection, multitasking

capabilities, network access,security, stability.

Answer—Windows XPProfessional and Windows

XP Home Edition.

Answer—Choice 2.

Answer—HP–UX.



3 HP–UX

4 IBM–AIX

Exercise ten How can Linux be used? (Circle one.)

1 As an operating system for personal computers

2 As an operating system for servers

3 Both of the above

Answer—Choice 3.


7 Systems development


• Analysis and design of computer programs• Programming and testing of computer programs

Analysis and designof computer

programs

The development of a computer program usually follows a fairly strict process. The following explains the first two of four steps.

First, the reason for the program needs to be analyzed: what problem needs to be solved? How long will it take? Is it feasible? Second, the structure of the program must be designed before any programming can begin.

Designing a simple computer program can be done quickly and with little effort. However, large programs can take hundreds of computer scientists years to complete.

The first step is to analyse the situation. The proposed program may be used internally by a company to improve efficiency. Maybe it is going to be sold commercially. Or perhaps it is being developed by an individual as a hobby. It must then be determined if the program should be created at all; is it feasible?

The second step is to design the program. The structure of a complex program must be designed in detail before it can be programmed. A document similar to a blueprint must be

Page 75


created. This document will show the foundation and structure of the program and will aid the programmers in creating the software.

Programming andtesting of computer

programs

The development of a computer program usually follows a fairly strict process. The following explains the last two of four steps.

Third, the application must be programmed into a computer using a programming language, and forth the application must be tested for defects and errors.

Programming a piece of software is done using a programming language. A programming language is a link between a computer, which can only read simple 1's and 0's, and a human, which likes to read words and sentences. A programming language will allow a human to write words, which will then be turned into a string of 1's and 0's, the form preferred by computers.

A very important step in the process is testing. Testing is an ongoing process that is done during the programming phase and extensively after the initial programming has been completed. All defects that arise from programming must be discovered and fixed.

This full four step process may be repeated several times before the program is completed. For example, a problem in the design phase may result in a reanalysis of the entire program.

Analysis Design Programming TestingAnalysis Design Programming Testing

Page 76 • 7 Systems development




Exercise one Once the idea for a piece of software has been determined, it is usually best to not waste any time and begin programming the software immediately. (Circle one)

1 True

2 False

Exercise two Of the choices below, which is a good reason for NOT going ahead with the development of a program? (Circle one)

1 Something better already exists and can be purchased cheaply

2 The problem the program is trying to fix will soon go away

3 It will take too long and cost too much money to develop

4 All of the above

Exercise three The four steps of developing software are typically done in sequence and not repeated. (Circle one)

1 True

2 False

Exercise four A programming language converts the words preferred by humans, into the 1ís and 0ís preferred by computers. (Circle one)

1 True

2 False

Answer—True.

7 Systems development • Page 77


Page 78 • 7 Systems development

8 Applicationsoftware


• Software versions• Application programs• Wordprocessing applications• Spreadsheet applications• Presentation applications• Database systems• Desktop–publishing applications• Graphic art design applications• Contact management applications• Large–scale computer applications

Software versions Over time software programs change and evolve. When enough changes have been made to a program the version will change. It may be necessary to update software for several reasons

• defects may be discovered in the program after it has been released

• new features or functionality may be added

• there may be a need to conform to various outside influences, such as accounting software adjusting to a change in the tax code

In many cases it may not be necessary to update your software each time a new version is released. Once you buy a piece of software, developers often provide a discount for updating to new versions.

Applicationprograms

Generally speaking, application programs are programs with which you can create new data files—business letters, balance sheets, data bases of names and addresses, slide presentations, newsletters, graphic art designs, etc.

When personal computers first came about, there were no application programs available. Thus, you had to be a programer or had to hire a programer to create the application programs

Remark that no one needs tobe a programmer to use a

personal computer.

Page 79


you needed. Naturally, an entire software industry quickly developed to fulfill the need—nowadays there are literally thousands of programs on the market to meet your needs. Some of these are described below.

Wordprocessingapplications

Wordprocessing applications allow you to create different kinds of documents—business letters, reports, manuals, etc. Sophisticated wordprocessing applications like Microsoft Word and Corel WordPerfect allow you to create very complex and rich documents with text, graphics, tables, indices, tables of contents, glossaries, etc.

Spreadsheetapplications

Spreadsheet applications allow you to create worksheets with numerical information—balance sheets, financial statements, expense reports, sales reports, etc. You can perform calculations in your worksheets by entering the appropriate numbers, formulas and functions. Microsoft Excel and Lotus 1-2-3 are well–known spreadsheet applications with which you

Indicate that wordprocessingis the single most commonuse of personal computers.

Remark that spreadsheetprograms are great for

studying different “what if...”scenarios.

Page 80 • 8 Application software


can create, edit and format worksheets containing text, numbers, formulas, functions, business graphs, etc.

Presentationapplications

Presentation applications are programs designed to help you create slide shows that can be printed on paper or transparencies, developed into 35 mm slides, displayed on the computer screen and projected onto a large screen before an audience. The best–known presentation application is Microsoft PowerPoint, with which you can create slide presentations including bulleted text, different types of 2–D and 3–D business graphs (bar graphs, pie charts, stock market charts, etc.), tables, organizational charts, still images, animated sequences, sounds, etc.

Indicate that sleek slidepresentations are nowadaysoften expected in sales and

business meetings.

8 Application software • Page 81


Database systems Database systems are often complex software packages. They are designed to create databases such as customer lists, company directories, parts catalogues, library records. Two of the most popular database systems are Microsoft Access and Corel Paradox.

These two database systems allow you to create, edit, update and maintain complex and relatively large databases. They allow you to order records in a variety of ways (e.g., alphabetically, numerically, chronologically by date, etc., in ascending or descending order), to search for records meeting very specific conditions (e.g., records where the state/province is California or Manitoba), to generate custom reports, etc.

Desktop–publishingapplications

Desktop–publishing applications are used to create publications that require special page layout and text flows, such as newsletters, magazines, newspapers, brochures, catalogues, etc., and which need to incorporate graphics (e.g., photographs, diagrams, maps, etc.) Among the

Remark that the databasemost people in the world arefamiliar with probably is the

telephone book.



best–known desktop–publishing packages one finds Adobe PageMaker, Quark Xpress and Microsoft Publisher.

Graphic art designapplications

Graphic art design applications are programs specifically designed to create or manipulate images such as drawings, scanned photographs, etc. The two most popular graphic art design applications are Adobe Photoshop and Corel Draw. Both of them allow you to do sophisticated work on newly created or existing images, including rotations, cropping, color manipulation, special effects, etc. For example, with a good graphic art design application you can remove unwanted elements from photographs (e.g., a telephone wire that spoils an otherwise beautiful picture of a sunset), apply special effects (e.g., show an area of an image as if seen through a curved lens), etc.



Contactmanagementapplications

Contact management applications are programs designed to help you manage your business contacts (potential or existing customers, suppliers, etc.) and tasks by providing you with an address book, calendar, time planner, appointment book, notepad for things to do, journal of entries, electronic sticky notes, electronic mail capabilities, etc. Microsoft Outlook and Act! are two of the most popular contact management applications.

Large–scalecomputer

applications

There are many widely used, large–scale computer applications in use today. Some large–scale business applications include

• online banking

• e–commerce

• remote access for employees

• processing incoming stock exchange deals

• some large–scale government applications include

• collection and calculation of taxes

• providing information on laws online

• storing census information

• coordination between the military

• maintaining the energy grid

Some large–scale healthcare applications include

• maintaining patient records

• storing information on various medications and treatments

• processing amounts owed and outstanding bills



• coordinating emergency response

Some large–scale education applications include

• taking online courses

• providing information for students online

• maintaining student records

• processing student loans

• research systems



Exercise one List below three types of data files that can be created with different application programs.

Exercise two Which of the concepts below is not normally associated with slide presentation applications?

Answer—For example, anythree of: business letters,

balance sheets, data bases ofnames and addresses, slidepresentations, newsletters,

graphic art designs.

Answer—Choice 2.



1 2–D and 3–D business graphs

2 Record sorting

3 Transparency printing

4 35 mm slides

5 Projection to audiences

Exercise three List below the names of two well–known wordprocessing applications.

Exercise four Which type of application program would you normally use to create the layout of a magazine?

1 A desktop–publishing application

2 A spreadsheet application

3 A contact management application

4 None of the above

Exercise five List below the names of two well–known spreadsheet applications.

Exercise six Briefly describe below the purpose of a contact management application.

Answer—For example,Microsoft Word, Corel

WordPerfect.

Answer—Choice 1.

Answer—For example,Microsoft Excel, Lotus 1-2-3.

Answer—To help youmanage your business

contacts.



Exercise seven List below the names of two well–known database systems.

Exercise eight Which one of the following applications is best suited to create a balance sheet?

1 Microsoft Outlook

2 Adobe Photoshop

3 Microsoft Excel

4 Corel Draw

5 None of the above

Exercise nine If you had to keep track of the meetings and business conversations you maintain with your customers, which of the following packages would be best suited to the task?

1 Corel Paradox

2 Microsoft Outlook

3 Adobe Photoshop

4 Corel Draw

Exercise ten Which of the applications below would be best suited to darken a scanned photograph?

1 Microsoft Excel

2 Lotus 1-2-3

3 Microsoft Access

4 Adobe Photoshop

Answer—For example,Microsoft Access, Corel

Paradox.

Answer—Choice 3.

Answer—Choice 2.

Answer—Choice 4.




9 Additionalsoftware


• World Wide Web browsers• Electronic mail programs• Games• Reference tool software packages• Educational software packages• Virus programs• Antivirus programs• Utilities programs

World Wide Webbrowsers

A World Wide Web browser, or just “browser” for short, is a program used to navigate through the Internet and view (browse through) the World Wide Web sites (pages of information) of companies and individuals across the world.

The two most widely used Web browsers are Microsoft Internet Explorer and Netscape Navigator. These two browsers let you see the text, graphics, video clips, animated sequences, etc. that have become standard fare in many Web sites.

Remark that a high–speedmodem has become a

necessity to browse the WorldWide Web comfortably.

Page 89


Electronic mailprograms

As their name indicates, electronic mail (or e–mail) programs allow you to send and receive electronic mail. You can send and receive electronic mail to and from other users in the local or wide area network used by your organization, or to and from users anywhere on the Internet. An example of well known electronic mail programs is the Microsoft Outlook.

A good electronic mail program allows you to compose new messages, to send them with or without copies to other people, to receive messages, to forward messages, to include attachments (i.e., documents, graphics, sound files, video clips, etc.) with your messages, etc.

Games Computer games are programs designed with the specific goal of entertaining the user. Some games are rather simplistic programs, but others can be very complex and sophisticated systems.

Some games, like Microsoft’s Flight Simulator, have outgrown the “game” designation and have become learning tools in their own right. Microsoft Windows 95 includes games like Solitaire, Minesweeper and 3–D Pinball Space Cadet.

Advise students to keep theire–mail messages brief and, if

needed, to includeattachments.

Warn students that somegames need a lot of memory

or disk space.

Page 90 • 9 Additional software


Reference toolsoftware packages

Reference tool software packages are programs that turn your personal computer into a reference tool. Examples of reference tool software packages include encyclopedias, text compilations of literary works, road atlases, thesauri, etc. Microsoft Encarta is a popular interactive multimedia encyclopedia containing articles on geography, history, science, art, etc. with text, images, video clips, animated sequences and sound.

Educationalsoftware packages

Educational software packages are designed with the goal of teaching the user about a particular subject or topic. Some of these programs are referred to as “edutainment software packages” because they are so well designed that they turn education into entertainment. The

Tell students that a fastretrieval engine is essential

in reference tool softwarepackages—waiting for

information to come up isvery tedious.

Remark that goodeducational software should

be engaging andentertaining.

9 Additional software • Page 91


software titles in the Microsoft Magic School Bus series are very popular among young children.

Virus programs Do not confuse a programing bug with a virus. A programing bug is a mistake in the code of a program which may result in the program’s malfunctioning. A virus, on the other hand, is a program that someone has written with the intention of doing harm. The most common ways of getting your computer system infected by a virus are to use diskettes that carry the virus or to inadvertently download via the Internet the virus hidden in a file. It is recommended that you run an up–to–date antivirus program often to check for possible virus infections.

Antivirus programs As its name indicates, an antivirus program is a program that can detect and remove viruses that have infected your computer system. The Norton Antivirus program is one of the most popular antivirus programs. As there are, unfortunately, new viruses being released every day,

Warn students againstunchecked programs or data

files.

Advise students to run andupdate their antivirus

program often.



one should upgrade one’s antivirus program to newer versions periodically as they become available.

Utilities programs Generally speaking, utilities programs are programs with which you do not create new data and which allow you to manipulate existing data. There are literally thousands of utilities programs, each of which has been designed for a particular task in mind. For example, there

Indicate that there areliterally thousands of utilities

one can download from theInternet for free or for a

small nominal fee.



are utilities programs that compress existing data so that it can all fit on a single diskette or so that it can be sent more quickly via e–mail through the Internet.

Other utilities programs are designed to change the shape and size of the MOUSE POINTER in Windows; others let you make transparent the background of graphics to be published on the Internet’s World Wide Web; and so on.





Exercise one Write below the names of the two most popular Web browsers.

Exercise two What type of program is the Microsoft Exchange client?

1 A wordprocessing application

2 A spreadsheet application

3 An electronic mail program

4 A Web browser

5 None of the above

Exercise three List below the names of two computer games that come with Windows 95.

Exercise four What type of program is Microsoft Encarta?

1 Utility program

2 Electronic–mail program

3 Reference tool software package

4 Spreadsheet application

Exercise five Briefly describe below what a virus is.

Answer—Microsoft InternetExplorer, Netscape

Navigator.

Answer—Choice 3.

Answer—Any two of:Solitaire, Minesweeper, 3–D

Pinball Space Cadet.

Answer—Choice 3.

Answer—A virus is aprogram that someone has

written with the intention ofdoing harm.



Exercise six Write below the name of a well–known antivirus program.

Exercise seven A common way of getting one’s computer system infected with a virus is by using diskettes without checking them first.

1 True

2 False

Exercise eight A computer bug and a computer virus are the same thing.

1 True

2 False

Exercise nine Briefly describe below what a programing bug is.

Exercise ten A program whose only feature is its ability to compress data would be a utility program.

1 True

2 False

Answer—For example,Norton Antivirus.

Answer—True.

Answer—False.

Answer—A programming bugis a mistake in the code of a

program which may result inthe program’s

malfunctioning.

Answer—True.


10 Overviewof the Internet


• Understanding the Internet• Origins of the Internet• The World Wide Web (WWW)• Web browsers• Links• Web sites• Web servers• Internet addresses and domain names• Domain types• Web addresses• Search engines• E–mail• E–commerce

Understanding theInternet

The term “Internet” is used to describe a massive global network of computers. In fact, a network of networks, the Internet is comprised of thousands of smaller regional networks scattered but connected throughout the world.

On any given day, the Internet connects millions of users all over the world. The Internet is a growing phenomenon, as every day more people become connected to it.

Origins of theInternet

The Internet started in the 1960s as a U.S. military/academic research system to ensure that communications would remain in place even in the event of a major (nuclear) war.

To this effect, computers at military, government and university facilities were connected via dedicated cables and phone lines. The Internet design is such that information sent through it will try to find alternative routes to arrive at its destination if the first chosen route is disabled.

Page 97


The World WideWeb (WWW)

The World Wide Web (WWW) is a body of information consisting of millions of documents (Web pages) published by companies, organizations and individuals. Web pages can contain:

• Text

• Graphics

• Animation

• Sound

• Video

Web browsers To display a Web page that has been published on the Internet’s World Wide Web, you need:

• A connection to the Internet (e.g., through a modem connected to a telephone line)

• A software package (a Web browser) that can read Web pages, such as Microsoft’s Internet Explorer, Netscape’s Navigator, or Mozilla Firefox

Web pages are created with a language called HTML (HyperText Markup Language) which Web browsers can read and thus display appropriately on your screen. The illustration below shows part of the HTML code of a Web page.

Page 98 • 10 Overview of the Internet


On the other hand, the illustration below depicts the way such a Web page is displayed by a Web browser (Microsoft’s Internet Explorer) on the screen.

Links Links—also known as “hyperlinks”—are strings of text or images included in Web pages that, when clicked, display other Web pages.

For example, a link labelled

How to buy

on a Web page, when clicked, may make your browser display a different page with details on how to buy the advertised products or services.

Often, links are identified on Web pages by underlined text, or by a change of color when the mouse pointer is taken to them, or by other visual cues.

Web sites A Web site usually consists of a collection of related Web pages which are linked together. Companies, government agencies, other organizations and individuals publish Web sites on

10 Overview of the Internet • Page 99


the Internet’s World Wide Web to advertise their products or services to existing and potential customers, and to provide useful information about themselves (e.g., annual reports, press releases, contact information, lists of strategic partners, etc.) The first page of a Web site is normally referred to as the “home page”. The home page of a Web site allows you to access—via links—the rest of the Web pages making up the Web site.

Web servers When a Web page (or an entire Web site consisting of multiple Web pages linked together) is created, it can then be stored in a Web server. A Web server is a computer which is connected to the World Wide Web and which allows people to access the Web pages stored in it through their browsers. That is, when a Web page is stored in a public Web server (“published”), users around the world can then view it by asking their browsers to display it.

Internet addressesand domain names

The Internet Protocol (IP) address of a page helps identify it. Domain names are simpler (and easier to remember) names mapped to specific IP addresses. Below are some examples of domain names.

• alignmedia.com (Align Media Inc.)

• hp.com (Hewlett–Packard Company)

• microsoft.com (Microsoft Corporation)

• astd.org (American Society for Training and Development)

• whitehouse.gov (The White House)



Domain types Different domains help identify the type of entity the domain holder is.

• com (commercial sites)

• edu (educational sites)

• gov (government sites)

• net (network administrative organizations)

• org (non–profit and other organizations)

Some domain types indicate the country of the organization holding the domain. For example,

• ca (for Canada)

• uk (for United Kingdom)

• de (for Germany—Deutschland in German)

• eg (for Egypt)

Web addresses By providing the Web address of a particular Web page, you can have your browser display it on the screen. Below are some examples of Web addresses.

• http://www.alignmedia.com

• http://www.hp.com

• http://www.hp.com/sbso/index.html

• http://www.microsoft.com

• http://www.astd.org

A Web address is also known as a URL, for Uniform Resource Locator.

Search engines Search engines allow you to find information contained in pages published on the Web. When looking for information on the Web, you can use the search engine that comes built–in with your browser, or a dedicated third–party search engine found in the Web such as

• Google (at http://www.google.com)

• Yahoo! (at http://www.yahoo.com)



• Ask (at http://www.ask.com)

• Excite (at http://www.excite.com)

E–mail The Internet allows you to send and receive e–mail to and from other users connected to the Internet. E–mail is one of the main uses of the Internet. In general, you can use two different types of systems to send and receive e–mail over the Internet:

• Client/server e–mail. This is the method adopted by most corporations. In this case, a computer system designated as the e–mail server accepts e–mail from the individual client workstations in the company and sends it out to the appropriate addressees. Similarly, the e–mail server accepts e–mail coming from the outside world via the Internet and distributes it within the company to its individual recipients at the client workstations. So to speak, an e–mail server acts as a post office for the company—all outgoing and incoming e–mail goes through it. In a client/server system—such as Microsoft Outlook, Mozilla Thunderbird, and Eudora—the client software resides in one’s computer, whereas the server software resides in the e–mail server

• Web–based e–mail. Web–based e–mail services such as HotMail, Gmail, Yahoo!Mail etc., allow you to send and receive e–mail through a Web site designed for this purpose.



In this case, you don’t need any e–mail software other than your Web browser. All incoming and outgoing e–mail is handled by the e–mail Web site.

E–commerce Making purchases online has become a very common practice. To make purchases online you must first access an online store through a Web browser.

Once you have decided on which products to buy you must supply a shipping address and, usually, your credit card information. Other methods of payment include money orders and certified cheques. Caution must be taken when giving away personal information. Be sure to only give information to sites you trust. Choose only large commercial sites like Amazon.com, Landsend.com, Powells.com etc., or sites that have been certified as secure.

Third party companies, like VeriSign, give certifications to Web sites. A certified Web site can usually be trusted with personal information.

The main advantages of using an online store are

• it is open all day, every day

• You can shop from the convenience of your home

• a wide range of products are available

• you still have consumer rights like the ability to return merchandise

The main disadvantages of using an online store are

• you don't get to see the product until it is delivered to you

• even if certified, the Web site might not be totally secure and your personal information might be stolen





Exercise one The Internet started as a military/academic research system. (Circle one.)

1 True

2 False

Exercise two What kind of information can Web pages contain? (Circle one.)

1 Text

2 Graphics

3 Animation

4 Sound

5 Video

6 All of the above

Exercise three Write below the names of two Web browsers.



Exercise four Write below what HTML stands for.

Exercise five A Web site usually consists of a collection of related Web pages which are linked together. (Circle one.)

1 True

2 False

Exercise six How is the first page of a Web site normally referred as? (Circle one.)

1 Cover page

2 Page one

3 Home page

4 Top page

5 None of the above

Exercise seven What are the computers in which Web pages are stored for public access called? (Circle one.)

1 Mail servers

2 Web browsers

3 Web servers

4 Hyperlinks

5 None of the above

Exercise eight Draw lines to connect each of the domain types below with its corresponding description.

1. edu A. government sites



Exercise nine Write below the names of three Internet search engines.

Exercise ten Write below the name of a Web–based e–mail system.

2. de B. non–profit organization sites

3. com C. United Kingdom sites

4. net D. German sites

5. ca E. educational sites

6. org F. Canadian sites

7. uk G. network administrative sites


11 Health, safety, and environment


• Ergonomics• Safety• The environment

Ergonomics Extended computer use can cause permanent injury. There are several simple techniques that can be used to decrease this risk.

Repetitive strain injury is a syndrome that is caused by performing repetitive tasks over a long period of time. This typically affects the nerves and muscles in the arm and back.

Repetitive strain injury is a blanket term for a number of other syndromes. The most common with computer use is carpal tunnel syndrome. Carpal tunnel causes pain in the wrists and is caused by improper posture when typing at a keyboard.

Some warning signs of repetitive strain injury are

• pain in the neck, wrist, elbow or back

• numbness in the extremities

• fatigue

• a tingling sensation

To help prevent repetitive stress injury

• maintain good posture while working, keep your feet flat on the floor and your back straight

• when typing, keep your wrists as flat as possible and your elbows bent at greater than 90 degrees

• stand up and walk around every 30 to 60 minutes to stretch your muscles

• every 15 minutes look away from the monitor and focus on something in the distance

• position the monitor at eye level about an arm's length away

• make sure that the difference in light level between the monitor and the surrounding area isn't too great, for example, don't position a monitor in front of a brightly lit window

Page 107


But most importantly, remember that these tips are a rough guide, ideally you should stop working before you feel any symptoms. To avoid permanent injury to your wrists, eyes, back, elbow and neck consult your physician if you continue to experience any pain or discomfort.

Safety Computers in general are very safe to use and operate. However, there are some situations that could cause harm or injury.

A large amount of voltage and current flow through a computer, which can be dangerous. If there any exposed or damaged wires shut off the computer immediately and replace the wires. Make sure all the connections are tightly secured into their slots. Do not place too many plugs into a single outlet, use a high quality power bar with surge protection. Leave the coverings on the computer case firmly attached, do not touch any cards or chips inside the computer. Even if the computer is turned off some of the internal components may retain an electric charge.

Consult a professional when replacing or repairing components.

The environment Computers can help to reduce the waste created in the home or office by allowing people to view documents on a monitor and not having to print them out on paper. However, it is more common that computer use harms the environment.

More often than not, all documents and e–mails are printed out when they don't have to be. This waste can be reduced by using recycled paper, printing on both sides of each page and only printing documents when necessary.

Old computer equipment can also be hazardous to the environment. The material used in manufacturing computer equipment can be toxic when released into a landfill. The ink in old printer toner cartridges can also be toxic. Old computer equipment should be properly recycled by a professional company when they are no longer needed.

The amount of energy consumed by computer equipment can also be reduced. Turning everything off when not in use can reduce consumption.

The Environmental Protection Agency in the United States certifies energy efficient equipment through the Energy Star logo.

Look for this logo when making purchases

Page 108 • 11 Health, safety, and environment




Exercise one It is not safe to ignore early warning signs of repetitive stress injury. (Circle one.)

1 True

2 False

Exercise two Which of the following can worsen the effects of repetitive stress injury? (Circle one.)

1 Slouching

2 Bad posture

3 Working for extended periods

4 All of the above

Exercise three Which of the following should never be attempted.

1 Touching the inside of the computer while it is powered on

2 Using old, frayed wires

3 Plugging a large number of computers and other devices into a single outlet

4 All of the above

Exercise four Which of the following is NOT a good technique to help protect the environment.

1 Recycling an old monitor that no longer works

2 Printing presentation notes using both sides of the paper

11 Health, safety, and environment • Page 109


3 Buying products with the Energy Star logo

4 Keeping a record of all your e–mails by printing them out

Page 110 • 11 Health, safety, and environment

12 PCsecurity


• Information security• Passwords• Understanding viruses• Effects of viruses• Preventing infection• Checking for viruses

Information security Information security is a term that refers to maintaining the secrecy and integrity of data. Data can be very important, and keeping the data secure even more so.For example, you may want to keep your personal medical files private, or you may have important business files that are very valuable.

A good policy for a company is to take a proactive approach to information security. A procedure should be in place for transferring sensitive files between locations and reporting breaches in security. It should be the duty of all employees to maintain information security.

Another common source of a breach in security is when equipment is lost or stolen. When a laptop, PDA, cell phone, Blackberry or flash memory stick is lost or stolen the data stored on the device could either be lost forever if there are no backups or if the data is confidential it could be made public.

All important data should be regularly backed up to another location and any confidential data should be encrypted. Encrypting data will prevent anyone without a secret key from viewing the data.

Passwords Typically when you log into a computer at the office you must supply a user name and password. The user name is usually set by your system administrator and will probably be based on your name. You will set your own password which should be kept secret.

Keeping your data private can depend on how good your password is. A strong password can prevent people from gaining access to your computer and viewing your data. A good policy is to change your password every three to six months. Do not use personal information that

Page 111


someone can guess, such as birthdays or telephone numbers. Use a mix of numbers and letters, upper and lower case, and if possible, avoid using proper nouns.

If you share your computer with other users, or if multiple users access the same hard drive over a network, then access rights will probably be set. Access rights will allow certain users to view and edit certain files. For example, each user on the system may have a personal folder that they can add files to. No other users on the system will be able to access those files. Your user name and password will determine which files and folders you can access.

Understandingviruses

A virus is a computer program that can replicate itself by making identical or modified copies of itself without permission from the end–user

The tasks that a virus carries out can be simple or quite complex, depending on the virus. For example, a virus can simply make a copy of itself, or it can enter your e–mail program and send copies of itself to each e–mail address found in it, or it can delete files in your hard disk randomly, or it can change the data contained in files, and so on. In other words, the least harmful of viruses may make a copy of itself and simply use up some resources in your PC, such as memory or hard disk space. But the worst of them can cause havoc in hundreds of thousands of PCs.

Like its biological counterpart–after which it is named–a computer virus needs a host in order to propagate. In the case of a computer virus, the host is another computer program. If a virus manages to make a copy of itself in the code of another computer program (a host), the latter is said to have been infected. It is through a host that a virus is loaded into a PC's memory. A host can be a computer game, or a macro (a small program inside a file to automate repetitive tasks), or any other file containing code that can be executed by the end–user or by the operating system. Once a virus is loaded into the computer's memory by its host, it looks for executable programs that it can infect in the computer. To do this, the virus must contain code that allows it to scan disks and other media looking for suitable executable files to become infected, including office applications, e–mail programs, utilities, scripts, macros, and so forth. In order to infect them, the virus must also contain code that allows it to make copies of itself. That is, viruses can search and reproduce.

Page 112 • 12 PC security


Finally, a computer virus must not be confused with a computer bug. A virus is a computer program that has been designed with the intention of causing harm, whether simple annoyance or irreparable damage.

A bug, on the other hand, is an error in programming that results in unwanted behaviour in a computer program (e.g., the program fails to print properly).

Effects of viruses In addition to searching and replicating, depending on what purpose they have been designed for, viruses may be able to attack, mutate, or encrypt themselves.

First, some viruses can attack the host's system by damaging its file system, by deleting partially or completely the contents of its hard disk, by modifying or destroying files the computer needs in order to operate, by displaying unwanted images, or messages on the screen, or by affecting the system in some other way.

Second, some viruses can also mutate. That is, some viruses can make copies of themselves that are not exact replicas of the original. This way, they can prevent or delay detection by antivirus programs, just as biological viruses (e.g., the flu virus) undergo mutations as they replicate themselves, thereby creating new strains that are immune or more resistant to existing vaccines. Computer viruses with this property must have in their code instructions to produce mutated copies of themselves.

Third, some viruses can encrypt themselves within the code of the host, making themselves invisible to antivirus programs trying to detect them.

Finally, two additional characteristics commonly found in viruses are:

• The fact that they are built with relatively small amounts of computer code. This makes them harder to detect by antivirus software

• The fact that they are installed and executed usually without the knowledge of the end–user. This allows them to propagate quickly and extensively

12 PC security • Page 113


Preventing infection Generally, a virus is attached to an executable file (i.e., a program) so that when the latter is run, the virus is activated and carries out the tasks it was designed to do. Examples of executable files include files with extensions such as exe, bat, com, js, vb, vbs, wsf, and others.

To reduce the risk of virus attacks, e–mail programs like Microsoft Outlook automatically block attachments that are considered potential threats. In addition, if your e–mail system uses Microsoft Exchange Server (as it is the case in many large organizations), the system administrator can control what file types are allowed to be received as attachments by the end–users.

A virus can make it into your computer system through different channels, including

• CDs

• USB Drives

• Diskettes

• Other portable file storage devices

• Attachments in e–mail messages

• Internet downloads

The following are rules of thumb to reduce the risk of infection:

• Do not use CDs, USB drives, diskettes or other portable devices from unknown sources

• Do not open e–mail messages that look suspicious

• In particular do not open files or unzip compressed files (files with the extension zip) that come as an attachment in an e–mail from an unknown source. Attachments with the extension exe, vb or com are prime suspects, as these identify executable programs. However, remember that document or worksheet files (often with extensions such as doc or xls) too may carry viruses embedded in macros

• Do not download files from Web sites you don't trust completely. Usually, the Web sites of large, well–known companies and organizations can be considered safe since they are constantly checked for viruses. However, there are many Web sites from which files can be downloaded and which are not safe.

• Install antivirus software and make sure it is running checking in the background for incoming viruses. If your antivirus software is constantly running while your PC is on, it may be able to detect attempts to infect your system and prevent them.

• Good antivirus software running in the background can check every e–mail message that you receive or that you send, to ensure that it is virus–free. If, on the other hand, your antivirus software is not running but is instead sitting idle in your hard disk, it can only be used to detect a virus attack only after it has occurred, and then there is no guarantee that it will be successful since some viruses disable antivirus software when they attack.

• Upgrade your antivirus software regularly. Remember, the vast majority of virus attacks (about 80%) are carried out by new viruses that the last version of antivirus software was not designed to catch. So to speak, there is an ongoing arms race between new viruses and new versions of antivirus software. So, keep your antivirus software up to date.

• Finally, use your antivirus software to scan disks and other media regularly, particularly media that comes from others



Checking forviruses

You can check for viruses in your system using antivirus software. As its name indicates, antivirus software can protect your system from virus attacks or, if you suspect that an existing file in a disk is already infected, it can detect the virus and remove it from the file. Removing virus code from the original code of a file code is called "disinfecting".

However, sometimes, even though it may detect it, the antivirus program cannot remove a virus from a file because its code is too entangled with the original code of the file. In such cases, the only alternative is to delete the entire file so that the virus is deleted with it.

In order to maximize the rate of success in detecting and eliminating viruses, it is important to keep one's antivirus program up to date so that it can handle the new viruses that are being released all the time.



Exercise one Which of the following could lead to lost or stolen data? (Circle one.)

1 Encrypting all files on a laptop

2 Preventing important data from being accessed remotely

3 Making regular backups of all data

4 None of the above

Exercise two Which of the following could make a good password? (Circle one.)

12 PC security • Page 115


1 123

2 3idZl4a3h

3 january17

4 secret

Exercise three Which of the following statements is false? (Circle one.)

1 In computer terminology, a virus and a bug are the same thing

2 In general, computer viruses can replicate themselves

3 A computer virus normally needs another computer program to propagate

4 An executable program can act as a host for a virus

Exercise four Which of the following statements is false? (Circle one.)

1 Some viruses can replicate by making copies of themselves which are slightly different from the original

2 Viruses are usually executed without the knowledge of the user

3 No virus can delete files the infected system needs to operate

4 In general, viruses are relatively small programs

Exercise five Assuming that you already have antivirus software installed in your computer, why should you upgrade to new versions regularly? (Circle one.)

1 Because antivirus software is inexpensive

2 Because new viruses are being released every day for which previous versions of the antivirus software do not provide protection

3 Because older versions of antivirus software have bugs that are fixed in newer versions

4 Because once the antivirus software has caught a virus and eliminated it, it cannot be used again to catch the same virus


13 Intellectualproperty


• Understanding copyrights• Proprietary, shareware and freeware software

Understandingcopyrights

Governments across the world can grant copyrights to individuals or companies on ideas and information. A copyright allows the copyright holder to use the idea or information as they wish but denies all others the same ability.

A lot of information you find on the Internet is copyrighted to some degree. Some copyrights forbid all use and reproduction, commercial or otherwise. While other copyrights allow information to be copied freely.

Software programs as well as images, music, sounds, video and text can all be copyrighted. If you plan on reproducing information found on the Internet, or from a CD, DVD or diskette, you should determine first if the data can legally be copied. For example, making a copy of a music CD you bought and giving the copy to a friend may break the copyright. Or, if you plan to reproduce an image found online for use on your own Web site you should first check the copyright status of the image.

Copyright laws are different from country to country, state to state, district to district. It is very important to check which copyright laws you are affected by, and if you have any doubt always consult a copyright lawyer.

Page 117


Proprietary,shareware and

freeware software

There are three common types of distributing software, the three main types are

• Proprietary software

• Shareware software

• Freeware software

Proprietary software is usually sold at a store or from a Web site. Once you buy the software you will have a full complete version of the program. Also, upon purchase you are usually given a product ID number. You will need to enter this ID number upon installation to activate the program. Since it is easy to copy the program from computer to computer, the ID number will prove that you are the purchaser of the software.

Shareware software is usually only downloaded from the Internet. At first, the application will either be missing some features or content, or will deactivate itself after a specified period of time. After using the software you may decide to buy it. Once you buy the software from the vendor they will send you instructions on how to release the full functionality of the program.

Freeware software is usually only downloaded from the Internet. Freeware is free to use. Once the application is downloaded and installed it will be fully functional for as long as desired. However, copying the data from person to person, or making changes to the application may still not be allowed.



Exercise one Which of the following can be copyrighted? (Circle one.)

Page 118 • 13 Intellectual property


1 Video

2 Music

3 Text

4 All of the above

Exercise two There is one common world wide copyright law. (Circle one.)

1 True

2 False

Exercise three Which types of software are usually only downloadable from the Internet and not found in stores? (Circle one.)

1 Freeware and shareware

2 Shareware and proprietary

3 Proprietary and freeware

4 No software is downloadable

13 Intellectual property • Page 119


Page 120 • 13 Intellectual property

14 Indexof terms

Numerics computer programs 75, 76 extensions 60
2000 Professional 672000 Server 703.1 643.11 6495 6598 67
Aadditional software 89addresses 100, 101analog versus digital 17analysis and design of computer

programs 75antivirus programs 92application programs 79application software 79applications 62, 80, 81, 82,

83, 84architecture 51art design applications 83assistant 4

Bbasics 13, 47bits and bytes 14browsers 89, 98bus standards 15bytes 14

Ccabling 52cache 21cameras 40, 41capacity 21card 16cards 51CD–ROM drives 26CD–ROMs 25chapter objectives 97, 107,

111, 117checking for viruses 115client / server architecture 51commerce 103computer applications 84computer families 1

computers 1, 3, 8computing 52connectors 52contact management

applications 84copyrights 117cost 16CPU 14cpu cache 21

Ddata files 59database systems 82design applications 83design of computer

programs 75desktop–publishing

applications 82development 75devices 31, 53digital 17digital assistant 4digital cameras 40disk 24diskette drives 22diskettes 23disks 24, 25domain names 100domain types 101domains 51DOS 62drives 22, 26, 27, 53DVD-ROM drives 27

Ee–commerce 103educational software

packages 91effects of viruses 113electronic mail programs 90e–mail 102engines 101environment 107, 108ergonomics 107evolution 62expansion card 16

extranets 8

Ffile names and extensions 60files 59formatting disks 24freeware software 118

Ggames 90graphic art design

applications 83graphical user interfaces 63GUI 63

Hhard disks 25hardware basics 13hardware concepts 13health, safety, and

environment 107humans or computers 8

Iinfection 114information security 111information technology 47intellectual property 117interface cards 51interfaces 63Internet 7, 97Internet addresses 100intranets 7

Jjoysticks 39

Kkeyboard 33

LLANs and WANs 48large–scale computer

applications 84

Page 121


lightpen 35links 99Linux 71local vs. shared devices 53

Mmail 102mail programs 90mainframes 1management applications 84Me 68memory 21microphones 41minicomputers 2modems 38monitor 31mouse 34multiple applications 62

Nnames 100names and extensions 60NetWare 70network basics 47network connectors 52network interface cards 51networks 6, 48, 49networks in computing 52nodes 51Novell NetWare 70NT Server 69NT Workstation 66

Oobjectives 97, 107, 111, 117operating system evolution 62operating systems 59, 61origins of the Internet 97overview of the Internet 97

Ppackages 91passwords 111PC security 111PCMCIA slots 16peripheral devices 31personal computers 3personal digital assistant 4plotters 37plug–and–play 16ports 15, 16presentation applications 81preventing infection 114printers 36Professional 67programming and testing of

computer programs 76programs 75, 79, 90, 92, 93property 117proprietary, shareware and free-

ware software 118publishing applications 82purpose of operating

systems 61

RRAM 22reasons for networks 49reference tool software

packages 91ROM 22running multiple

applications 62

Ssafety 108safety, and environment 107scale computer applications 84scanners 39screen monitor 31search engines 101security 111Server 69, 70server architecture 51servers 50, 100shared devices 53shared drives 53shareware and freeware

software 118sites 99slots 16software 59, 79, 89, 118software packages 91software versions 79speaker 42speed versus cost 16spreadsheet applications 80standards 15storage 21supercomputers 5system evolution 62systems 59, 61, 82systems development 75

Ttape drives 27technology 47telephone networks in

computing 52teleworking 54testing of computer

programs 76the environment 108touch–screen technology 39trackball 34types 101types of computers 1

Uunderstanding copyrights 117

understanding the Internet 97understanding viruses 112Unix 70USB ports 16user interfaces 63utilities programs 93

Vversions 79versus cost 16virus programs 92viruses 112, 113, 115

WWANs 48Web 98Web addresses 101Web browsers 89, 98Web servers 100Web sites 99Windows 2000

Professional 67Windows 2000 Server 70Windows 3.1/3.11 64Windows 95 65Windows 98 67Windows Me 68Windows NT Server 69Windows NT Workstation 66Windows XP 68wireless LAN 49wordprocessing

applications 80Workstation 66workstations 50World Wide Web 98World Wide Web browsers 89WWW 98

XXP 68

Zzip disks 24

Page 122 • 14 Index of terms

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