A computer is an electronic machine.

Computers take input in the form of

data,

process it, store it, and produce results

in the form of meaningful information.

Data refers to raw input that, when processed

or arranged, makes meaningful otput.

Information is usually the pocessed outcome

of data. For example, a list of ten numbers in

a random order can be the data usedfor a

sorting program. After sorting the numbers

ina a program in ascending or descending

order, the numbers become information.

o Speed: A computer works very

fast. It can do a large number of

calculations within a second.

o Large Memory: A computer can

store a lot of information in its

memory for further use.

o Accuracy: A computer always

works accurately. If your data is

correct, then the result will also

be correct.

o Continuous Work: A computer

never gets tired and never gets

bored. It can work continuously

for a long period of time.

o A computer cannot think on

its own.

o A computer does not learn

from experience.

o Its work depends on the

instructions given by the

Input means to put in a computer works

with data or information that we feed into it.

This data can be in the form of words,

numbers, characters, and pictures

such as your name, your age, marks, and

phone numbers.

Data can be entered by using input devices

like a keyboard

and mouse or by transferring information

from a file or a database system.

The data entered is called the input. A

randomly ordered list of a class of

students can be input.

The action to convert data into

meaningful information is called

processing. It involves entering,

summarizing, analyzing, or otherwise

converting data into usable

information. Sorting the student list

into

alphabetical order is a process.

Output is the result given by the

computer after the data processing,

so output or information is processed

data. The alphabetically sorted list of

the students

is the output.

Keep your computer clean and dry and away from direct sunlight.

Keep your computer away from heat sources, such as electric heaters.

Do not place the computer near objects that create strong magnetic fields, such as stereo speakers.

Do not use a mobile phone when you are near your computer.

Type gently on the keyboard. Do not hit the keys too hard.

Never put anything except your disks into the disk drives.

Do not eat or drink near your computer.

Use antivirus and spyware programs to protect your computer from harmful software.

Put the computer on a flat table at a comfortable height and distance. Make sure that the display is a bit below your eye level, to avoid

hurting your eyes.

Place the computer so that it is directly in front of you when you work. Make sure you have enough space to operate the various parts

of the computer (keyboard, mouse, etc.) easily.

Set your chair height so that the keyboard is at (or slightly below) the level of your elbow. You should be able to type comfortably with

your shoulders relaxed.

Your knees should be slightly higher than your hips. If necessary, use a foot rest to raise your knees.

Set the back of your chair so that it supports the lower part of your spine.

Put the computer so that sunlight or bright indoor light does not reflect off the screen and hurt your eyes.

If possible, use soft, indirect lighting in your computer work area.

Change your position often. If you use a computer for a long time, stand up and stretch your wrists, hands, and legs regularly.

Every fifteen or twenty minutes, look at an object that is far away, to avoid hurting your eyes with too much close work.

Take frequent short breaks (for example, two or three minutes every half hour) instead of one or two long breaks.

Computers come in various sizes and with different capabilities. They may be classified into several categories, including supercomputers,

mainframe, server, desktop, laptop (notebook), netbook, and palmtop computers, according to their size and functions.

Supercom

puters

Mainframe Computers

Servers

Desktop & Laptop Computers

Tablets & Smartphones

Computers that are designed to be used

by a person are usually called personal computers

(PC). Laptop, netbook,

and palmtop computers are designed for mobile

use. Mobile devices can be

used away from a power outlet using a rechargeable

battery. Laptop and other

mobile devices are also called portable computers.

Supercomputers are the fastest computers

on earth. Supercomputers are very expensive

and are used for specialized applications

that need huge amounts of mathematical

calculations. For example, weather forecasting

requires a supercomputer. Other uses of

supercomputers include animated graphics,

fluid dynamic calculations, nuclear energy

research, and petroleum exploration.

The main difference between a supercomputer

and a mainframe is that a supercomputer uses

all its power to execute a few programs as

quickly as possible whereas a mainframe uses

its power to execute many programs at the

same time for multiple users.

The supercomputers of the past eventually

become the personal computers of today.

Therefore, your home PC most likely has more

computing power than many supercomputers

from previous decades.

A mainframe computer is a large, powerful, and expensive

computer.

Many people can use the power of a mainframe computer at

the same

time, using either a PC (Personal Computer) or a dumb

terminal.

A PC performs a lot of processing itself. A dumb terminal

uses the

mainframe computer to do all the processing, then simply

shows the

results on a screen. Large organizations, such as banks and

insurance

companies, use mainframe computers.

Servers are expensive, powerful, dependable, and dedicated

computers. A

server provides services to all the computers or terminals

that are connected

to it. Applications are stored in this computer, and the other

computers

(terminals) connected to it can access them. There are

different types of

servers depending on the tasks they perform. For example a

domain server is

responsible for managing network (domain) resources. It

stores user account

information, authenticates users, and enforces security policy

for a domain.

Web servers are computers that deliver (serve up) web

pages. A database

server stores the databases and processes database

queries. An FTP

server is dedicated to storing files. Any user on the network

can upload and

download files on the server.

Desktop Computers

A desktop computer is designed to be

used by one person at a time. These

computers are kept on the desk, so they

are called desktop computers. A typical

desktop computer PC consists of a system

unit, a monitor, a keyboard, and a mouse.

Laptop Computers

Like desktop computers, laptop computers are designed to

be used by one

person but, like a suitcase, these computers can easily be

carried by a person

anywhere.

Tablet PCs have touch screens with keyboards. This is the

main difference

between them and laptop computers.

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