3

Table of Content

Sr. No

ContentPage No

01 Introduction 03

02 What is Computer 03

03 Importance of Computer 05

04 Input Devices 06

05 Keyboard 07

06 Special Feature of Keyboard 09

07 Main Types of Keyboard 10

08 Mouse 10

09 Types of Pointing Devices 12

10 Scanner 14

11 Types of Scanner 15

12 Microphone 18

13 Joystick 21

14 Digital Camera 22

15 Drawing Tablet 23

16 Bibliography 24

4

Introduction

A computer is not just a keyboard, a screen and a square grey box that has

a slot in the front where you place your disks. These are only parts of a

computer or computer system.

A typical computer system contains:

A processor which is able to manipulate data very quickly Devices used for getting information into and out of the system Some means of storing instructions and the information which has been

processed.

There are various devices attached to the main processing unit these

devices are called peripheral devices. The bits and pieces of electronic

circuitry are referred to as hardware.

The hardware on its own can do nothing. In order to make a computer

carry out useful tasks, we must give it instructions. These instructions take

the form of computer programs, also called software.

What is Computer

When the first, primitive computer was charged up, the men and women

involved in the early years of computing likely had no concept about

where the computer would take society. Indeed, those of us who log on to

computers daily cannot really envision where this technology will take us

into the future. Along with not being able to clearly predict where we will

5

end up in the future as far as computers are concerned, as the technology

progresses new terminologies also come into being or vogue.

Computer definitions change and expand as often as a new version of

popular software is created and marketed. In the early years of computing,

computer definitions were small in number yet a complete mystery to the

average man or woman on the streets. Computers and computer definitions

- words and terms used to describe the newborn technology - were not

often heard in every day conversation. Computer definitions remained

inside laboratories and research centers where the technology was being

developed.

In this day and age, thanks in part to the prevalence of computers in every

day life and thanks in part to the extent the World Wide Web has invaded

so many aspects a computer user's life, computer definitions are common

in typical daily parlance. In the 21st century, despite the rapid change and

development of hardware and software, computer definitions related to the

technology are frequently included in the typical discourse of the average

Consumer.

Indeed, in this day and age, the typical computer user - and even folks who

are not regular computer users - have basic comprehension and

understanding of computer definitions.

Computer definitions will continue to develop and change into the future.

But, in this age of instant communications, new computer definitions likely

will never be foreign to a computer user for a very long time.

According to Sinha (2004)

A machine that can be programmed to manipulate symbols. Computers can perform complex and repetitive procedures quickly, precisely and reliably and

6

can quickly store and retrieve large amounts of data. (P.06)

The physical components from which a computer is constructed (electronic

circuits and input/output devices) are known as "hardware". Most

computers have four types of hardware component: CPU, input, output and

memory. The CPU (central processing unit) executes programs

("software") which tell the computer what to do.

Input and output (I/O) devices allow the computer to communicate with

the user and the outside world. There are several kinds of memory - fast,

expensive, short term memory (e.g. RAM) to hold intermediate results, and

slower, cheaper, long-term memory (e.g. magnetic disk and magnetic tape)

to hold programs and data between jobs.

According to Norton (2002)

An electronic device that has the ability to store, retrieves, and process data, and can be programmed with instructions that it remembers. The physical parts that make up a computer (the central processing unit, input, output, and memory) are called hardware. Programs that tell a computer what to do are called software. (P.08)

Importance of Computer

By the time your current freshman class graduates it is estimated that 75%

of all jobs in Pakistan will be computer related or computer dependent. It is

required to encourage all education majors to quickly acquire computer

skills and to continue to develop these skills throughout their educational

program if they want to be competitive in the job market.

7

With computers and technology becoming more and more common place

in most professions this same advice should also apply to all students,

regardless of major. By becoming computer literate you can make use of a

word processor to write reports, research papers and other assignments.

Additionally, you can make use of Spell Checkers and Grammar Checks to

improve your written documents.

There are many other advantages of being able to use a computer -- for

example, you can make use of computers at numerous locations around

campus to gain access to the reference section of the library. It is

encouraged to take a general education class with a computer focus or

attend any of the numerous training sessions around university

Computers have become an integral part of day to day life. Since the

advent of personal and home computers, they have become an integral part

of the education system. Having computers as a part of ones education can

prove very helpful. Being good in studies and computers can secure better

job prospects, in this age and time computer knowledge is a must.

The computer networks these days have a powerful impact on the ways

which individuals, private organizations can communicate with each other.

This age is known as the era of IT Education, where every application is

linked with computer technologies. The use of computers can make

business transactions very accurate, thus keeping a proper record of profit

and loss. Computers play a very vital role in education.

Input Devices

8

Any machine that feeds data into a computer is called Input Device. For

example, a keyboard is an input device; Input devices other than the

keyboard are sometimes called alternate input devices. Mice, trackballs,

and light pens are all alternate input devices.

1. Keyboard

2. Mouse

3. Microphone

4. Digital Camera

5. Joystick

6. Scanner

7. Drawing Tablet

Input and output devices allow the computer system to interact with the

outside world by moving data into and out of the system. An input device

is used to bring data into the system. Some input devices are:

1. KEYBOARD

The keyboard is an input device. It has letter and number keys, and

what are called function keys, computer specific task keys, that allow you,

the user, to use an English-like language to issue instructions to an

electronic environment.

It is the primary input device. It uses a cursor to keep your place on the

screen and to let you know where to begin typing. You are able to input

commands, type data into documents, compose documents, draw pictures

9

with use of certain keys, pull down menus, and respond to prompts issued

by the computer. Almost all computers require you to use a keyboard

unless, of course, it is adapted for individuals with disabilities or for a

specified alternative input devices.

The keyboard contains special keys to manipulate the user interface. When

a key is touched, an electrical impulse is sent through the device which is

picked up by the operating system software, and sent through the computer

to be processed.

The keyboard operates as a typical typewriter and uses a standard

"QWERTY" keyboard. QWERTY is the way the keyboard is set up for

typing. If you look at the keyboard under the top number row, you will see

that the alphabet top row begins with QWERTY.

A device for putting information into a computer. In fact this is one of the

two main input devices (the other being a mouse). The computer keyboard

was adopted from the typewriter keyboard. In fact, a good portion of the

computer keyboard is identical to those found on any typewriter, including

the QWERTY key layout. There are additional function keys, generally

marked F1 through F-12 arranged across the top of the keyboard, generally

above the QWERTY keys.

10

There is generally a numeric key pad on the right hand side of the

keyboard. Between the QWERTY keys and the numeric key pad are sets of

keys generally used for navigating around the monitor screen. The reason

that the term "generally" is used so often here is that layout can vary from

manufacturer to manufacturer. Today's computer keyboard for an IBM-

compatible computer generally contains 104 keys.

Special Features of Keyboard

1. Numeric keypad:

This portion of the keyboard allows you to use the keyboard like a

calculator and input numbers into application programs. It has a Num lock

key that when depressed, will activate that portion of the keyboard so that

numbers can be entered. When the lock key is not on, there are arrow keys

on the keys which then work to move the cursor in different directions.

The "NUM LOCK" key is a toggle key which switches back and forth

between these two modes.

2. Caps Lock:

The "CAP LOCKS" key works in this same manner as the "NUM

LOCK" key. If the Cap Lock is lit on your screen the keyboard will type

only in capitals. If the Cap Lock light is not lit it will type only in small

letters.

3. Function Keys:

The function keys are used to initiate commands on help menus or

database programs especially before the development and use of computer

pointing devices. They are still used extensively today as options on the

keyboard to pull down menus or to be programmed to do specific functions

in application programs.

11

Ctrl or Shift keys also work with Function keys to add more commands to

programs and what are called shortcuts, ways to operate functions like

saving and deleting without going through elaborate features and steps.

Short cuts speed up typing and input into the computer.

4. Escape Key:

One of the most important keys is the escape key. It usually cancels

the last command or takes you back to the previous step in a program.

Main Types of Keyboard

Keyboards come in may shapes and sizes. They can be large and small,

almost like a custom car. They come in various colors and can be designed

specifically for the user, especially in the case of the disabled.

QWERTY:

The most popular is the standard QWERTY keyboard. The newer

keyboards can have a trackball built into the keyboard. This allows the

user the convenience of a built in pointing device. The trackball acts as the

mouse and saves time and space in the work area.

ERGONOMIC:

This keyboard is built so that the keyboard is divided into two parts.

One half fits the right hand and the other half fits the left hand. This split

keyboard arrangement is built to fit the natural positioning of the hand and

to help with repetitive motion hand injury which occurs when a job is

carried out over and over again, such as in keyboarding.

12

2. MOUSE (Pointing Device)

A pointing device is an external tool that is used to move objects

around and also to select options from menus. The pointing device is an

element of the graphical user interface. It manipulates on screen objects to

issue commands. Examples of pointing devices include the mouse,

trackball, light pen, pen for graphic tablet, joystick, touch screen, wand,

head mounted display, virtual reality glasses, and 3-D mouse.

The concept of the pointing device was developed in

1970 by Douglas Engelbart as another way to input

information into the computer other than through the

keyboard. This input device has become popular and

with the growth of the graphical user interface it has

become one of the most necessary and important tools of the computer.

The mouse is a hand operated device which controls a pointer on the

monitor screen. The pointer on the screen is called a cursor. The mouse

generally allows one to enter information to the computer faster than using

just the keyboard. The mouse was originally developed for the Apple

Macintosh computer and was later developed for the IBM-compatibles. 

The mouse is included in almost every computer that is sold today. Besides

becoming an important input tool, it has provided access to the computer

for many individuals with disabilities that might not otherwise have the

opportunity to use the computer. The pointing device also lets you double

click on an icon to start a program application; and in the WINDOWS 95

operating system you can use the mouse to drag a file or document to the

Recycling Bin to delete a file.

13

The computer mouse moves by way of a roller and ball system. When you

move the mouse across the desktop, the ball underneath rolls. This ball

corresponds to the position of what is called a pointer on the screen. The

pointer is usually shaped like an arrow, though some people like to change

their pointer to look like objects. (One person in our group has changed his

pointer to an ink pen icon.) When you move the pointer around it is called

mousing.

The speed of the mouse can be managed by your

computer operating system software, or a

commercial application program for your mouse.

You can drag objects on the screen by clicking on the object, holding down

on the mouse button, and rolling the mouse across the desktop until you

get the object to a new location. When you reach the spot that you want, let

go of the mouse button.

Most mice come with two buttons. You use the left button on the mouse to

do most selecting of objects. The right button can be used for some menu

actions. This is especially true when using browser software to examine

and manipulate pictures and graphics on the Internet.

There is a three button mouse and the middle button can be programmed

for specific application software, but usually the two button mouse is used

the most. If you are left handed, you can change to a left-handed mouse

option in your software so that you can use your mouse in your left hand.

Types of Pointing Devices

14

1. PEN

The pen lets you draw on what is called a digitizing tablet that

mirrors the surface area of the computer screen. The pen can be used as a

standard mouse (without wires connected to it) or also as a free flowing

drawing device. The pen is useful for drawing since drawing graphics with

a mouse tends to be somewhat difficult.

2. MOUSE

The mouse is a hand held device that lets you point to and selected

items on your screen. In a PC mouse there are mostly 2-3 buttons and on a

Mac there is one. A ball under the mouse senses movement. To ensure

smooth motion your should remove the ball and clean it regularly.

3. CORDLESS MOUSE

The cordless mouse is a lot better than a normal mouse thus by

reducing the clutter of the work space needed to move the mouse around.

This mouse runs on a battery. When you move the mouse it sends an

infrared beam to a sensor which interprets it causing it to move.

4. TRACKBALL

The trackball is an upside-down mouse that remains stationary on

your desk. It is the same principle as the mouse except that the rollers are

reversed and the ball is on top. This ball does not need as much attention as

the normal mouse because the only thing that touches it is your hand as the

normal mouse touches a surface.

15

5. TOUCHPAD

The touchpad has sensors that sense your touch. When they sense

your touch they send a signal to the computer to move the mouse pointer to

that location on the screen.

6. LIGHT PEN

The light pen system allows the user to touch the computer screen

with a lighted pen to activate commands and make selections.

7. TOUCH SCREEN

The touch screen lets the user touch the area to be activated by using

the finger or hand. Touch Screen - A touch screen is a computer screen or

other screen that you can touch with your finger to enter information. 

Examples of touch screens include a smart board, a microwave, a

dishwasher, or an ATM at a bank.

A basic touchscreen has three main components: a touch sensor, a

controller, and a software driver. The touchscreen is an input device, so it

needs to be combined with a display and a PC or other device to make a

complete touch input system.

8. Head Mounted Virtual Reality Displays, Wands, Special

Trackballs, Data Gloves, and Special 3-D Flying Mice that can go in six

different directions- These devices are currently the newest pointing

devices.

3. SCANNER

16

Scanners allow a pc to convert a picture or object into digital code that

allows the computer to display and use an image. A scanner's

sophistication is the ability to translate an unlimited number of analog

voltage levels to digital values.

The computer is not able to use graphics unless they are in a form that they

can understand. The scanner takes the information it sees on a page and

converts into code that the computer can use. A picture once scanned can

be edited, printed, or used in an application. Scanners can come with

specialized software called optical character recognition (OCR). This

software can read text as printed or written. The information can then be

manipulated in the computer.

Important Note: A feature of the scanner is the resolution. This is how

sharp and detailed the scanner can read. Scanners are measured in dots per

inch. The higher the resolution, the more the memory that is required to

scan the file. The bigger the file that is produced. Larger files take longer

scanning time.

If a file is big and you need to fit it on a diskette, you may run into a

problem storing it unless you store it to the hard drive or another high

capacity drive. Therefore, if you are wanting to produce a file for screen

output, you should scan at 72 dpi because that the best resolution that the

monitor can display. It is the same of the printed output. If you only have a

300 dpi printer, do not scan the file at a higher resolution since the printer

will only print it at that resolution.

17

Types of Scanners:

1. Sheet-Fed Scanner

Sheet-fed scanners have mechanical rollers that move the paper past the scan head.

How it work

Gray Scale: Using black and white and shades of gray, the scanner is able

to translate the image into gray scales. Why would you use a gray scale

scanner? If you plan to print on a black and white printer, it is most cost

effective since color ink is so expensive. Text is best done on a grayscale

scanner.

Color: A color scanner scans images in red, blue, and green shades. This

scanner is more expensive in terms of final print output . A color scanner

usually costs more than a gray scale scanner. If you plan on doing

presentation work, work with color photographs, or any sort of task that

requires a color output, then use a color scanner. With this scanner you can

also choose options of scanning such as line art (scanning the image only

in black or white), grayscale (black, white, and shades of gray, or color

(shades of red, blue, and green).

2. Flatbed Scanner

Flatbed Scanners have a glass window where the item to be scanned is

placed on top of a while the head moves past the item. This method is

similar to a xerox machine.

18

How It Work

1. A light source underneath the picture or document illuminates the

image. Spaces white or blank reflect more light than do inked and colored

areas.

2. A motor moves the scan head underneath the page. when the

scanhead is moving it captures light that was reflected from individual

areas of the page about 1/90,000 of an inch

3. Light from this page is bounced through an intricate system of

mirrors that must continually pivot to keep the light beams aligned with a

lens.

4. A lens focuses the beams of light into light sensitive diodes that

translate the amount of light into an electric current. The amount of the

current depends on the amount of light reflected, the greater the amount of

light reflected the greater the current.

5. The analog to to digital (A-D) converter stores each analog reading

of voltage as a digital pixel representing either a black or white area.

Scanners that are more sophisticated can translate the voltage into shades

of gray. In a color scanner, the scan head makes 3 passes under the image

and the light on each pass is directed through a red, green or blue filter

before it strikes the original image.

6. The digital information is sent to the pc where it is translated into a

format that a graphics program can read.

3. Hand Held Scanners

19

Hand held scanners are small, portable scanners that depend on a

human operator to move the head across the the object or image to be

scanned. .

How It Work

1. On the majority of handheld scanners when you press the scan

button a light-emitting diode (sometimes called a LED) illuminates the

image below the scanner. An inverted, angled mirror that sits right above

the scanner's window reflects the image onto a lens in the back of the

scanner.

2. The lens focuses a single line of the image onto a CCD (known as a

charge coupled device), which is a component designed to detect subtle

changes of voltage. As the light shines onto sever rows of light detectors

located on the CCD, each registers the amount of light as a voltage level

that equals to black,white or gray.

3. Special analog chips receive light voltage generated by the CCD for

gamma correction. This process enhances the black tones into an image

that is that the eye will have be able to recognize the shades of the image

easier.

4. The line of the image now is moved to the analog-digital converter.

In a gray scale scanner, the converter assigns 8 bits to each pixel, or 256

shades of gray.

5. As the disk turns, a light shines through the slits and is detected by

a photomicrosensor on the other side of the disk. When light strikes the

sensor it throws a switch that sends a signal to the A-D converter. This

signal tells the converter to send the line of bit generated to the computer.

Then the converter clears itself of the old data.

20

6. The computer then moves to the next line.

4. Microphone

A microphone, which was originally invented by Emile Berliner in 1877,

is a device which allows you to record voices or sounds and place them

onto computers, generally as a wav file. Microphones also can be used

with other applications such as a voice dictation program or a voice

conference program.

While not all computers come with microphones, a

microphone can be purchased at a local retail store such

as radio shack or any other retail store. When purchasing

a microphone, it is not always necessary to purchase a

microphone capable of recording extended frequencies as the normal

human voice is only capable of going so high or low.

When connecting the microphone to the back of the

computer, the microphone will be placed in the hole

which generally has Mic or Microphone written

next to it as illustrated in the above illustration.

While generally Microphones are a separate computer component, some

manufacturers are integrating the microphone into computers. Generally,

integrated microphones can be found on laptops and some desktop

21

monitors. Integrated Microphones are usually a small hole in front of the

computer which when spoken into will record your voice.

A microphone is an example of a transducer, a device that changes

information from one form to another. Sound information exists as patterns

of air pressure; the microphone changes this information into patterns of

electric current. The recording engineer is interested in the accuracy of this

transformation, a concept he thinks of as fidelity.

A variety of mechanical techniques can be used in building microphones.

The two most commonly encountered in recording studios are the

magneto-dynamic and the variable condenser designs.

1. Dynamic Microphone

In the magneto-dynamic, commonly called dynamic, microphone, sound

waves cause movement of a thin metallic diaphragm and an attached coil

of wire.

A magnet produces a magnetic field

which surrounds the coil, and

motion of the coil within this field

causes current to flow. The

principles are the same as those that

produce electricity at the utility company, realized in a pocket-sized scale.

It is important to remember that current is produced by the motion of the

diaphragm, and that the amount of current is determined by the speed of

that motion. This kind of microphone is known as velocity sensitive.

2. Condenser Microphone

22

In a condenser microphone, the diaphragm is mounted close to, but not

touching, a rigid backplate. (The plate may or may not have holes in it.)

A battery is connected to both

pieces of metal, which

produces an electrical potential,

or charge, between them. The

amount of charge is determined

by the voltage of the battery, the area of the diaphragm and backplate, and

the distance between the two. This distance changes as the diaphragm

moves in response to sound. When the distance changes, current flows in

the wire as the battery maintains the correct charge. The amount of current

is essentially proportioinal to the displacement of the diaphragm, and is so

small that it must be electrically amplified before it leaves the microphone.

A common varient of this design uses a material with a permanently

imprinted charge for the diaphragm. Such a material is called an electret

and is usually a kind of plastic. (You often get a piece of plastic with a

permanent charge on it when you unwrap a record. Most plastics conduct

electricity when they are hot but are insulators when they cool.) Plastic is a

pretty good material for making diaphragms since it can be dependably

produced to fairly exact specifications. (Some popular dynamic

microphones use plastic diaphragms.) The major disadvantage of electrets

is that they lose their charge after a few years and cease to work.

5. Joystick

23

The joystick is a hardware input device used for games and/or flight

simulators. This device is used to maneuver a particular item throughout

locations.

Along with the capability of maneuvering items, the joystick will also have

a series of buttons which can be programmed to fire weapons, add

acceleration as well as several other possibilities, depending upon the

program.

A joystick is used to move the cursor from place to

place, and to click on various items in programs.  A

joystick is used mostly for computer games.

6. Digital Camera

A type of camera that stores the pictures or video it takes in electronic

format instead of to film. There are several features that make digital

cameras a popular choice when compared to film cameras.

First, the feature often enjoyed the most is the LCD display on the digital

camera. This display allows users to view photos or video after the picture

or video has been taken, which means if you take a picture and don't like

the results, you can delete it; or if you do like the picture, you can easily

show it to other people. Another nice feature with digital cameras is the

24

ability to take dozens, sometimes hundreds of different pictures. To the

right is a picture of the Casio QV-R62, a 6.0 Mega Pixel digital camera

used to help illustrate what a digital camera may look like.

Digital cameras have quickly become the camera solution for most users

today as the quality of picture they take has greatly improved and as the

price has decreased. Many users however are hesitant in buying a digital

camera because of the inability of getting their pictures developed.

However, there are several solutions in getting your digital pictures

developed. For example, there are numerous Internet companies capable of

developing your pictures and send you your pictures in the mail. In

addition, many of the places that develop your standard cameras film now

have the ability to develop digital pictures if you bring them your camera,

memory stick, and/or pictures on CD.

Digital Camera - A digital camera can be used to take pictures.  It can be

hooked up to a computer to transfer the pictures from the camera to the

computer.  Some digital cameras hold a floppy disk, and the floppy disk

can be taken out of the camera and put directly into the computer.

7. Drawing Tablet

Drawing Tablet - A drawing tablet is similar to a white board, except you

use a special pen to write on it and it's connected to the computer.  Then

the word or image you draw can be saved on the computer.

25

Bibliography

1. White, Ron (1993) How Computer WorkLondon: Ziff-Davis Press,

2. White, Ron (1993) How Software WorkLondon: Ziff-Davis Press,

3. Evans, C (1977) Pioneers of Computing, Oral History of Computing London: Science Museum,

4. Fifer, S (1961) Analog Computation: Theory, Techniques, Applications New York: McGraw-Hill

5. Goldstine, H., (1972) The Computer from Pascal to von Neumann Newyork: Princeton University Press

6. Huskey, H.D (1947) The State of the Art in Digital Computing New York: Britain and the United States press,