Computers are information processing machines that consist of both hardware and software working together to accomplish tasks. Hardware refers to the physical components like the CPU, memory, and input/output devices. Software includes programs that give instructions to computers. A computer system has a central processing unit that processes instructions and data, input and output units to accept and communicate information, and a storage unit to hold instructions and data. Computers are used in many fields like science, education, medicine, engineering, entertainment, communication, business, banking, publishing, and more. They help analyze data, present information, assist in design and manufacturing, and automate many tasks.

1. THE COMPUTER SYSTEM
Computers are information processing machines. A computer system consists of
both hardware and software working together to accomplish tasks.
Hardware:
Hardware refers to the physical components of the computer system which
consists of the CPU, memory, input devices and output devices.
Programs:
Every computer must be instructed step by step on what to do and how to
do exactly. Such instructions given to computers are called programs.
Software:
Software refers to a set of programs designed by the programmer or
manufacturer to facilitate automatic functioning of the computer.
Peripherals:
The input and output devices are called as Peripherals. Some examples of
peripherals are keyboards, mouse, monitors and printers.
Components of a Computer System
A computer system basically comprises the following four components:
1. Central Processing Unit (CPU): This unit processes instructions and data.
2. Input Unit: This unit accepts instructions and data.
3. Output Unit: This unit communicates the result to the user.
4. Storage Unit: This unit stores instructions and date.
Central Processing Unit (CPU):

2. Central Processing Unit is the heart of the computer system. It interprets the
instructions given and the operations to produce the desired output. It has links
with the input and output devices.
The CPU itself has three parts internally:
1. Arithmetic and Logic Unit (ALU): This unit performs the arithmetic and
logical operations on the input. Data is transferred from the memory unit to the
arithmetic logic section, processed, and returned to internal storage.
2. Control Unit:This unit is the coordinator of the computer system. It makes the
program instruction from the primary storage unit, interprets them, and ensures
correct execution of the program. It also controls the input/output devices and
directs the overall functioning of the other units of the computer.
3. Memory Unit: This unit stores the instructions and data for performance. It
holds the intermediate results during the course of calculations and provides the

3. data as and when required. This internal storage is also called primary memory
or main memory.
Input Unit:
This unit gather the data and convert into the form that the computer can
understand. Some of the input devices are the keyboard and the mouse. Input
devices are controlled by the user. For example, typing on the keyboard or
clicking on a mouse button.
Output Unit:
Output units are devices that display information from the computer
(CPU). Output devices are controlled by the computer. Some of the commonly
used output devices are printer, monitor, speakers and plotter.
Storage Unit:
Computers use secondary storage devices extensively to store data and
instructions. The device that holds a disk is called a disk drive. All personal
computers available in market at present have one non-removable hard disk (or
hard disk drive) and a DVD (Digital Video Disk) drives. CD-ROMs (Compact Disk
Read Only Memory) and DVDs can be used to store data. Some common storage
devices are floppy disks, hard disks CD-ROM, DVD, tape drives, pen drive and
removable hard drives.
Working mechanism of a computer:
A computer process the data by a Step-by-step instruction set called as
running a program. A computer functions as follows:
Step1:
The computer accepts input, it can be given either by typing data through a
keyboard, or reading from a disk.
Step 2:

4. The computer processes the data according to the instructions given in a
program. Ex: sorting a list of words or numbers, and modifying documents
according to user instructions.
Step 3:
The computer stores data. A computer must store data so that it is available for
processing at a later time if needed. Most computers have more than one
location to store data.
Step 4:
After the process of the input information the computer produces output. Some
examples of computer output include reports, documents and graphs. Computer
outputs can be produced on paper as printouts (hard copy), displayed on screenor
stored in a CD (soft copy).
APPLICATION OF COMPUTERS
Computers are all around us and avoiding them is virtually impossible. We
interact with computers in our daily lives. Whether we are at the cinemas, the
school, or the public library. The beginnings of computer literacy are already
apparent.
 Science:
Computers are used by scientists to develop theories, analyse and test data.
In Space applications and weather forecasting are few examples.
 Education:

5. The educational system is undergoing a revolution with the use of
Computers in classrooms.
Chalk and board concept is being replaced by
 ICT (Information Communication Technology)
 PowerPoint presentations
 Computer based tutorials and e-learning
 Multimedia
 Animations
 Graphics and charts etc.
Many boring topics can be made interesting using multimedia.
Students could access internet for online help and courses for more
information.
 Medicine and health Care:
 Computers are helping greatly to monitor the extremely ill in the
intensive care unit (ICU) and provide cross- sectional views of the
body.
 It is greatly reducing human made and mistakes.
 Doctors use computers to assist them in diagnosing certain diseases of
the sort.
 Computers are used greatly in managing patients, doctors, wards and
medicine records, as well as deal with making appointments,
scheduling surgeries and other likes.
 Engineering / Architecture / Manufacturing:
 Architects and engineers use computers extensively in designing and
drawings.
 Computers can create three dimensional (3D) objects that can be
viewed from all the three dimensions.
 Computer Aided Manufacturing (CAM) is used in designing a
product, ordering the parts, and production planning.
 Manufacturing units use computer to coordinate the entire
manufacturing processes

6.  Entertainment:
 The entertainment industry utilizes computers to its maximum for
Animation, cartooning, special effects on sound, music and light etc.
 Computers are effectively used in films like Titanic, The Zurrasic
Park and Avatar etc.
 Communication:
 Email, Messages and reports are passed from one person to one or
more persons with the aid of computer and telephone line.
 Chatting allows communication among loved ones to get connected
from wherever they are.
 Video Conferencing is another communication medium where one
need not travel across places to present themselves.
 Business Application:
 All businesses today use computers for storing their personnel data,
inventory and pay bill preparation.
 In retail markets, products from meats to magazines are packed with
zebra-striped bar codes that can be read by the computer scanners
 Trading of shares globally is possible only with computers.
 E-Commerce is gaining momentum with the use of internet and
websites which brings the merchandise to people’s doorstep.
 Banking:
 ATM cards are used every where now which let us bank any time we
want.
 PC banking (Personal Computer Banking) let us view our bank
balance, request transfers between accounts and pay bills
electronically.
 Publishing:

7.  Desk Top Publishing (DTP) uses computers for publishing all kinds of
documents
 Colorful Digital banners can be created to suit the taste of the
customer.
 DTP is used for designs ranging from visiting cards to large
billboards.
 Sports:
 In sports computers are used widely in combination with video
cameras. These are used to record the motion of all the sports men.
 3D programs are used later on to help the trainers see their
movements and to improve their styles of playing.
 Traffic light control:
 In traffic light control the computer is being employed to drive the
traffic light.
 Programmed codes like “turn off the red light” or “turn on the red
light” to control the traffic light.
 Training:
 It is much cheaper and effective to teach pilots how to fly in a
computerized cockpit are simulators, than or real air planes.
 Railway engineers can also be given some kind of training on how to
run a train with the help of a computerised system.