The document provides an introduction to the basic concepts of computers including defining a computer, describing common computer hardware components like the CPU, memory, and storage devices, and explaining different types of computer software like operating systems, programming software, and applications. It also classifies computers by size from supercomputers to personal digital assistants and provides examples of common computer hardware and software components.

1. UNIT 1: FUNDAMENTALS OF COMPUTER
Leaning Outcome
Introduction
1.1 Defining a computer
1.2 Computer hardware
1.3 Computer software
Quick summary
Assignment
References
At the end of the Unit, you will be able to:
• Define a computer
• Understand how a computer works
• List computer hardware and software
In various Modules before this, you have been introduced to the concept of Information and
Communication Technologies (ICTs). Today, ICT has become very important for the
development of any country since it can facilitate and enable people to have access to
information quickly. ICTs are at the heart of your telecentre.
The computer in your telecentre is one of the important ICT tools. It helps you in providing
many critical services to your community. So, it is critical to learn more about the computer
and its components. In this Unit, you will be introduced to the basic concepts of computer
and its components.
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2. A computer is an electronic device that operates under the control
of a set of instructions. A computer accepts data from an input
device and processes it into useful information, which is displayed
on its output device.
Actually, a computer is a collection of hardware and software
components that help you accomplish many different tasks.
Hardware consists of the computer itself, and any equipment
connected to it. Software is the set of instructions that the computer follows in performing a
task.
1.1.1 Classification of computers
Computers can be classified by their size and performance. The size of a computer often
determines its function and processing capacity. The size of computers varies widely from
tiny to huge and is usually dictated by computing requirements. Some of the major types of
computers are listed below:
Supercomputers
The largest computers are supercomputers. They are the most
powerful, the most expensive, and the fastest ones. They are
capable of processing trillions of instructions per second.
Examples of users of these computers are governmental
agencies, such as the Railway system, the National Weather
Service, and the National Defence Agency. Also, they are used in
the making of movies, space exploration, and the design of many
other machines.
Mainframe computers
Mainframe computers process data at very high rates of speed,
measured in millions of instructions per second. They are very
expensive, costing millions of dollars in some cases. Mainframes
are designed for multiple users and process vast amounts of data
quickly. Banks, insurance companies, manufacturers, mail-order
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3. companies, and airlines are typical users of such computers. Mainframes are often ‘servers’,
i. e., computers that control a network of computers.
Microcomputers
Microcomputers can be divided into two groups -- personal computers
and workstations. Workstations are specialised computers that
approach the speed of mainframes. Often microcomputers are
connected to networks of other computers, whereas a personal
computer is a standalone computer. Most of the telecentres use a
personal computer.
Notebook and Laptop computers
A notebook computer can fit into a briefcase and
weighs less than two pounds, yet it can compete
with the microcomputer. A larger and heavier
version is called a laptop computer.
Personal digital assistant
The smallest computer is the handheld computer called a Personal Digital
Assistant or a PDA. PDAs are used to track appointments and shipments
as well as names and addresses. PDAs are also called pen-based
computers because they utilise a pen-like stylus that accepts hand-
written input directly on a touch-sensitive screen.
The computers of all sizes have common characteristics. Some of these are: speed,
reliability, storage capacity and productivity. It is capable of storing enormous amount of
data that must be located and retrieved very quickly. There are two components of a
computer: hardware and software. You will learn about these components in the following
section.
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4. Any computer system has two components, namely hardware and software. The physical
equipments connected to a computer system comprise the hardware. The computer
hardware is responsible for performing four basic functions: input, processing, output and
storage.
1.2.1 Input devices
Input devices send data and instructions to the Central Processing Unit (CPU), which acts
like the brain of the computer. You can talk/ communicate with the CPU through the input
devices. These include, Key board, Mouse, Scanner, etc. Let us learn about each of these
input devices below:
Keyboard
The keyboard is probably the most used input device. It operates a lot like
a typewriter, but it has many additional keys that let it do special things
that a typewriter can’t do.
Mouse
Another input device is called a mouse, because of it’s shape. The cable
attaching it to the computer looks a bit like a tail. When you move the mouse,
you’ll see a small moving arrow. This arrow is called the pointer. Using this
pointer, you can provide data to the computer for processing.
Scanner
A scanner is a very useful input device. You can place a page of writing or
pictures in the scanner and it will send the information to your computer. There
they can be changed, saved into a computer file, or printed.
Some of the other input devices are Web camera and the Joystick.
1.2.2 Processing devices
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5. Once information is sent to a computer by one of the input devices, it is processed. The
computer uses it’s brain or the CPU to process the information.
A processing unit consists of different components, which are bound together into a simple
box called Cabinet. Some of the key processing devices are listed below.
Motherboard
Your computer couldn’t work without the motherboard. The
motherboard ties all the processing components together. It allows
every part of your computer to receive power and communicate with
each other. Everything that runs the computer or enhances it’s
performance is either part of the motherboard or plugs into one of it’s
expansion slots or ports.
Processor
The processor is the main brain of the computer. When preparing
the specification of a computer, one should know the clock rate or
clock speed of a computer. It is the fundamental rate in cycles per
second (which is measured in hertz) for the frequency of the clock
in any synchronous circuit. The higher the processing speed, the
higher the output.
Random Access Memory (RAM)
RAM is a temporary memory. The computer holds information in this memory and
gets it when needed.
If a computer has more RAM, it can solve problems and process information faster. If
you’re updating your computer, more RAM is a great thing to add.
Hard Disk Drive (HDD)
The Hard Disk Drive is a magnetic storage device. All the computer
programmes and files you create and save are located there. This is
permanent storage. The hard drive is normally signified by the letter “C”.
Today’s hard drives can store a huge amount of information.
Power Supply Unit (PSU)
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6. If there is any one component that is absolutely vital to the operation of a
computer, it is the power supply. Without it, a computer is just a box full
of plastic and metal. The power supply converts the alternating current
(AC) line from your home or school to the direct current (DC) needed by
the computer.
You can see the power supply from the back of your computer because of the power cord
and the cooling fan. Computers generate a lot of heat and need the fan to keep them cool
from overheating.
1.2.3 Output devices
An output device displays the processed information to the user. Some of the prominent
output devices are Monitor, Printer, Speaker, etc.
Monitor
The monitor looks like a TV and lets you see your work and files. The monitor produces
output that is temporary—the output is lost when it is rewritten or erased or when power is
lost. The Monitor output is called the softcopy.
Printer
The printer displays output in a permanent manner; it is called the hardcopy. The printer
prints exactly what’s displayed on the screen of the monitor.
Speaker
Speakers can be connected to your computer, so that you can hear very realistic sound
effects and wonderful music. Some computer monitors come with built-in speakers.
1.2.4 Storage devices
The secondary storage devices store data and programmes permanently. These include CD/
DVD-ROM, Pen drive, External Hard disk, etc.
CD/ DVD-ROM
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7. CD-ROM stands for Compact Disk-Read Only Memory. They are flat, shiny disks that store
information. Most new computers have CD-RW drives. CD-RW stands for Compact Disk-
ReWrite. This type of disk allows you to write information to it, as well as read from it. Most
of them can hold up to 700 megabytes of information.
The newest computers come with the option of a DVD drive. A DVD (Digital Video Disc)
looks just like a CD, but holds much more information. They can store 4.7 gigabytes of
data.
Pen drive
The pen drive is a portable USB flash memory device that can be used to quickly transfer
audio, video, and data files from the hard drive of one computer to another.
External hard disk drive
An external hard disk drive is a type of hard disk drive connected to a computer by a USB
cable or other means. It can be easily carried and used in any computer.
The hardware devices may be very important, but they are useless without the instructions
that control them. These instructions that are used to control hardware and accomplish
tasks are called software. In computers, software is anything, but hardware. Software can
be categorised into the following three main types:
i. System software
ii. Programming software
iii. Application software
1.2.1 System Software
System software acts as an interface between hardware and computer applications in a
computer. The system software includes Device Drivers and Operating System in a
computer. Device Drivers specifically integrate Operating system and Hardware Devices,
such as scanner, webcam, Hard Disk Drive, etc.
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8. Operating System
An operating system of a computer, which comes under System Software class, interfaces
between hardware and the user. It coordinates resource allocation for computer
applications, which run on a computer and coordinates and manages activities of a
computer. Some of the popular operating systems are different UNIX flavours, Linux,
Microsoft Windows, Mac, etc.
1.2.2 Programming software
Programming software provides tools to assist programmers to write computer application
programmes. Programming software includes compilers, debuggers, linkers etc.
1.2.3 Application Software
Application Software allows end user to run applications, which allow them to carry out one
or many tasks. Some of the most popular general applications are Open Office and Microsoft
Office, which also includes financial applications and accounting packages.
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9. 1. Miller, Michael (2002), Absolute Beginners Guide to Computer Basics, Que: USA
2. White, Ron and Downs, E. Timothy (2003), How Computers Work, Que: USA
3. Wikipedia resources on computers (http://en.wikipedia.org/wiki/Computers)
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