Computer COMPUTER PDF.,,,,,,,,,,,,,,,,,,

PREPARED BY: DIL MOHAMMAD 1
COMPUTER FUNDAMENTALS
INTRODUCTION
The term computer is derived from the word ‘compute’, which means ‘to calculate’.
The impact of computers in our day-to-day life is tremendous and visible in all fields.
Similarly in modern libraries, various activities are performed with the help of
computers.
OBJECTIVES
After completing through this lesson, you will be able to:
● define a computer, identify its characteristics and functions;
● list types of computers;
● explain hardware and software;
● recognize Input and Output units and devices; and
● list types of operating systems;
WHAT IS A COMPUTER
Computer is an electronic device which is capable of receiving information or data
and perform a series of operations in accordance with a set of operations. This
produces results in the form of data or information. Computer is a machine capable
of solving problems and manipulating data. It accepts and processes the data by
doing some mathematical and logical operations and gives us the desired output.
Therefore, we may define a computer as an electronic device that transforms data
into information. Data can be anything like marks obtained by you in various
subjects, it can also be name, age, sex, weight, height, etc. of all the students in
your class or income, savings, investments, etc. of a country.
BASIC COMPUTER OPERATIONS
A computer basically performs five major operations or functions such as :
● Accepts data or instructions by way of input.
● Stores data,
● Processes data as required by the user,
● Gives results in the form of output, and
● Controls all operations inside a computer.
Each of these operations are discussed and shown in the figure given below:

Let us know the details of basic computer operations.
Input
This is the process of entering data and programs in the computer system. Therefore,
the input unit takes data from us to the computer in an organized manner for
processing.
Storage
The data and instructions are saved/ stored permanently in storage unit. The storage
unit performs the following major functions:
● All data and instructions, before and after processing, are stored here, and
● Intermediate results of processing are also stored here.
Processing
The task of performing operations like arithmetic and logical operations is called
processing. The Central Processing Unit (CPU) takes data and instructions from
the storage unit and makes all sorts of calculations based on the instructions given
and the type of data provided. After this data is sent back to the storage unit.
Output
This is the process of producing results from the data for getting useful information.
The output produced by the computer after processing is stored inside the computer
before it is given to you in human readable form. The output is also stored inside
the computer for further processing.
Control
Controlling of all operations like input, processing and output are performed by
control unit. It takes care of step-by-step processing of all operations inside the
computer.
COMPUTER SYSTEM
In order to carry out its operations, a computer system is divided into three separate
units. They are: 1) Arithmetic logical unit, 2) Control unit, and 3) Central processing
unit. All these three units are known as functional units.
Arithmetic Logical Unit (ALU)
The processing of the data and instructions are performed by Arithmetic Logical
Unit. The major operations performed by the ALU are addition, subtraction,
multiplication, division, logic and comparison. For processing, data is transferred
from storage unit to ALU. After processing, the output is returned back to storage
unit for further processing or for storing purpose.
Control Unit (CU)

The next component of computer is the Control Unit, which acts like the supervisor
seeing that things are done in proper way. The control unit determines the sequence
in which computer programs and instructions are to be executed. Activities like
processing of programs stored in the main memory, interpretation of the instructions
and issuing of signals for other units of the computer to execute them are carried
out by CU. It coordinates the activities of computer’s peripheral equipment which
include input and output devices. Therefore, it is the manager of all the operations
mentioned in the previous section.
Central Processing Unit (CPU)
The ALU and the CU of a computer system are jointly known as the central
processing unit (CPU). You may call CPU as the brain of any computer system. It
is just like brain that takes all major decisions, makes all sorts of calculations and
directs different parts of the computer functions by activating and controlling the
operations. The CPU (Central Processing Unit) is the device that interprets and
executes instructions.
A computer system includes a computer, peripheral devices, and software.
CHARACTERISTICS OF COMPUTER
Let us now identify the major characteristics of a computer. These are:
Speed
As you know computer can work very fast. It takes only a fraction of a second for
calculations that manually take hours to complete. It takes few minutes for the
computer to process huge amount of data and give the result.
Accuracy
The degree of accuracy of computer is very high and every calculation is performed
with the same accuracy. The accuracy level is determined on the basis of design of
the computer. The errors in computer are mainly due to human and inaccurate data.
Diligence
A computer is free from tiredness, lack of concentration, fatigue, etc. It can work
for hours without any error.
Versatility
The computer is highly versatile. You can use it for a number of tasks simultaneously
such as, for inventory management, preparation of electrical bills, preparation of
pay cheques, etc. Similarly, in libraries computer can be used for various library
housekeeping operations like acquisition, circulation, serial control, etc. and also
by students for searching library books on the computer terminal.

Power of Remembering
Computer has the power of storing large amount of information or data. Any
information can be stored and recalled whenever required for any numbers of years.
It depends entirely upon you how much data you want to store in a computer and
when to retrieve or delete stored data.
Dumb Machine with no IQ
Computer is a dumb machine and it cannot do any work without instructions from
the user. It performs the instructions at a tremendous speed and with great accuracy
as it has the power of logic. It is for you to decide what you want to do and in which
sequence. So, a computer cannot take decision of its own as human beings can take.
Storage
The computer has an in-built memory where it can store huge amount of data. You
can also store data in secondary storage devices such as CDs, DVDs, and pen drives
which can be kept outside the computer and can be carried to other computers.
GENERATION OF COMPUTERS
The history of computer development is in reference to different generation of
computing devices. The first-generation computers appeared in mid-1940s. The
present day computer, however, has undergone rapid changes for the last seven
decades. This period, during which the evolution of computer took place, can be
divided into five distinct phases known as Generations of Computers that are being
presented in the table given below: -
TYPES OF COMPUTERS
Present day computers can be categorized as below:
a) Super Computer
Supercomputers are fastest computers and are very expensive. These are employed for specialized applications that
require immense 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.

b) Mainframe Computer
It is a very large and expensive computer and is capable of supporting hundreds, or even thousands of users
simultaneously. In the hierarchy that starts with a simple microprocessor (in watches, for example) at the bottom and
moves to supercomputers at the top, mainframes are just below supercomputers. In some ways, mainframes are
more powerful than supercomputers because they support simultaneous programs. But, supercomputers can
execute a single program faster than a mainframe
Mainframe Computer
The chief difference between a supercomputer and a mainframe is that a supercomputer channels all its power into
executing a few programs as fast as possible, whereas a mainframe uses its power to execute many programs
concurrently.
c) Mini Computer
It is a mid-sized computer in size and power. It lies between workstations and mainframes. In the past decade, the
distinction between large minicomputers and small mainframes has blurred. In general, a minicomputer is a
multiprocessing system capable of supporting from 4 to about 200 users simultaneously.
Minicomputer

d) Micro Computer
i. Desktop Computer: a personal or micro-mini computer sufficient to fit on a desk.
Desktop Computer
ii. Laptop Computer: a portable computer completes with an integrated screen and keyboard. It is generally smaller
in size than a desktop computer and larger than a notebook computer.
Laptop Computer
iii. Computer/Digital Diary /Notebook /PDAs (Personal Digital Assistant): a hand-sized computer, Palmtop, does not
have keyboard, but its screen serves both as an input and output device.

e) Workstations
It is a terminal or desktop computer in a network. In this context, workstation is just a generic term for a user’s
machine (client machine) in contrast to a “server” or “mainframe.”
Work station
HARDWARE AND SOFTWARE
Hardware
Hardware refers to the physical equipment used for the input, processing, output and storage activities of a
computer system. It consists of mechanical and electronic devices, which we are able to see and touch easily. Some
of them are central processing unit (CPU), primary storage devices, secondary storage devices, input and output unit
and communication devices. These are explained below: -
● Central processing unit (CPU): It manipulates the data and controls the tasks performed by the other components.
● Primary storage: It stores temporarily data and program instructions during the processing.

● Primary memory (main memory): These are RAM (Random Access Memory/Read-Write Memory), and ROM
(Read-only-memory).
● Secondary storage: These store data and programs for future use. These are Hard Disk (Local Disk) and External
Hard Disc, Optical Disks, (CDR, CD RW, DVD-R, DVD-RW), Pen Drive, Memory Cards, etc.
Secondary Storage Devices
Communication Devices: These are used for communication or flow of data from one computer to another
computer. Some of them are Modem, Switch, Router, TV tuner card, etc.
Communication devices
Software
A computer cannot do anything on its own. It has to be guided by the user. We have to give a sequence of
instructions to the computer in order to do any specific job. Software is simply a computer program or a set of
instructions. Software guides the computer at every step indicating where to start and stop during a particular job.
The process of software development is called programming.
Types of software
There are two types of software, namely, system software and application software.
System software
System Software are general purpose programs designed to perform tasks such as controlling all operations required
to move data into and out of the computer. It communicates with keyboard, printer, card reader, disk, tapes, etc. It
also monitors the use of various hardware like memory, CPU, etc. System software acts as an interface between
hardware and application software. Remember that it is not possible to run application software without system
software. Some of the system software are Disc Operating System (DOS), Windows, Unix/Linux, MAC/OS X etc.

Application software
It is a set of programs, which are written to perform specific tasks of the users of computer. These software are
developed in high level languages to help the user to get the computer to perform various tasks. Some of the
application software are MS Office, Macromedia (Dreamweaver, Flash, Freehand), Adobe (PageMaker, Photoshop),
LIBSYS, SOUL, WINISIS, KOHA, etc.
INPUT AND OUTPUT UNIT
An input and output unit consist of two parts namely, input devices and output devices. Normally, an Input and
output unit can control one or more peripheral devices. These units are explained below:
Input Unit
The data is entered / input into the computer through input devices. The input devices translate the data /
information from a natural language in which the user is working, into the machine language which the computer can
understand. Computer language is in the form of binary code (0 and 1). Input devices are classified as follows:
● Human data entry devices - keyboard, mouse, joystick, trackball, digitizing labels and; pick devices - light pen touch
screens.
Keyboard Scanner
Web Camera Joystick
Input Devices
● Source data entry devices (Audio input –speech recognition; video input digital camera; scanners - optical scanner
OCR, OMR, MICR, Barcode Reader). Pictures of some of the source data entry devices are given…

Barcode Reader Microphone
Optical Mark Reader Magnetic Card Reader
Output Unit
The output unit accepts output data from computer via output devices and transforms the data into human readable
form. All the information inside the computer is in the form of binary digits (0 and 1). Output devices convert them to
numbers, words, graphics, sound and motion which we can easily understand.
Output devices are classified as
● Hard copy device (Printer, Plotter, Computer Output on Micro-film)
● Soft copy devices (Monitor, Visual Display Terminal, Video Output and Audio Response). Output devices are shown
in Fig.
Monitor Printer

Video Output Audio Unit
OPERATING SYSTEM
An Operating System is a system software that acts as an interface between a user and hardware of a computer.
Modern operating systems usually feature a graphical user interface which uses a pointing device such as mouse or
keyboard for input. Operating Systems are viewed as resource managers that manage the resources of a computer.
The main resource is the computer hardware which is in the form of processors, storage, input/output devices,
communication devices, and data. A good operating system should be efficient, reliable, take short time in execution
of programs, occupy small memory as small as possible.
The main Operating Systems are:
1.Network Operating System
– WINDOWS 2000
– Unix
– Linux
2.Desktop Operating System
– WINDOWS
– DOS (Disc Operating System)
– Mac OS
3.Mobile Operating System
– Palm OS
– Pocket PC
Some of the operating system are presented in the following table along with their main characteristics:

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