Post Graduate Diploma in Computer Application

353 Pages·2014·4.82 MB·English

PDCA - 01
VARDHAMAN MAHAVEER OPEN UNIVERSITY, KOTA
Post Graduate Diploma in Computer Application
(PGDCA)
Computer Fundamental and System Software
Course Development Committee
Chaiman
Prof. (Dr.) Naresh Dadhich
Vice-Chancellor
Vardhaman Mahaveer Open University, Kota
Convener / Coordinator Members
Prof. (Dr.) D.S. Chauhan 1. Prof. (Dr.) S.C. Jain
Department of Mathematics Engineering College, Ajmer
University of Rajasthan, Jaipur
2. Prof. (Dr.) M.C. Govil
Member Secretary / Coordinator
M.N.I.T., Jaipur
Sh. Rakesh Sharma
Assistant Professor (Computer Application) 3. Dr. (Mrs.) Madhavi Sinha
V.M. Open University, Kota A.I.M. & A.C.T., Jaipur
Editing and Course Writing
Editor
Prof. (Dr.) S.C. Jain
Department of Computer Engineering
Engineering College, Ajmer
Writers
1. Prof. (Dr.) M.C. Govil 4. Sh. Daya Krishan Gupta
Department of Computer Engineering Modi Institute of Technology,
M.N.I.T., Jaipur Kota
2. Dr. S.S. Sarangdevot 5. Sh. Sanjay Verma
Director Computer Centre Modi Institute of Technology,
Rajasthan Vidyapith, Udaipur Kota
3. Sh. Rajeev Shrivastava
HOD (Department of Computer Science)
L.B.S. College, Jaipur
Course Supervision and Production
Director (Academic) Director (Material Production & Distri-
bution)
Prof. (Dr.) Anam Jaitly Prof. (Dr.) P.K. Sharma
Vardhaman Mahaveer Open University, Vardhaman Mahaveer Open University,
Kota Kota
Production July 2007
All rights reserved. No, part of this book may be reproduced in any form by mimeograph or any other
means, without permission in writing from the V.M. Open University, Kota.
Printed and published on behalf of V.M. Open University, Kota by Director (Academic).
Index
Unit Number Unit Name Page Number
1. Introduction to Computer System 4 - 30
2. Storage Devices 31 - 44
3. Hard disk Drives Interface 45 - 58
4. Input Devices 59 - 70
5. Output Devices 71 - 94
6. Representation of Number System 95 - 121
7. Study of Logic Gates 122 - 155
8. Operating system Concept 156 - 169
9. Process Management 170 - 193
10. Memory Management 194 - 215
11. File System 216 - 236
12. Dos Operating System 237 - 278
13. Windows Operating system 279 - 320
14. Linux Operating System 321-351

UNIT 1: Introduction To Computer Systems
Structure of the Unit
1.0 Objective
1.1 Introduction
1.2 Classification and Applications
1.3 Overview of the Computer System
1.4 Input and Output Devices
1.5 Personal Computer Configuration
1.6 Computer Languages
1.7 System Softwares
1.8 Summary
1.9 Unit End Questions
1.10 Glossary
1.0 OBJECTIVES
After going through this unit we will be in a position to
· Define a computer system
· Classify computer and Application
· Understand the basic organization of computers
· Understand the Arithmetic Logical Unit, Control Unit and Central Processing Unit
· Define computer memory
· Differentiate between input devices and output devices
· Distinguish between compiler and interpreter
· Describe the use of Interpreter, Assembler, Linker and loader
· Differentiate between different types of language
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1.1 INTRODUCTION
Let us begin with the word ‘compute’. It means ‘to calculate’. We all are familiar with calculations in
our day-to-day life. We apply mathematical operations like addition, subtraction, multiplication, etc.
and many other formulae for calculations. Simpler calculations take less time. But complex calculations
take much longer time. Another factor is accuracy in calculations. So man explored with the idea to
develop a machine, which can perform this type of arithmetic calculation faster, and with full accuracy.
This gave birth to a device or machine called ‘computer’.
The computer we see today is quite different from the one made in the beginning. The number of
applications of a computer has increased, the speed and accuracy of calculation has increased. You
must appreciate the impact of computers in our day-to-day life. Reservation of tickets in Air Lines and
Railways, payment of telephone and electricity bills, deposits and withdrawals of money from banks,
business data processing, medical diagnosis, weather forecasting, etc. are some of the areas where
computer has become extremely useful.
However, there is one limitation of the computer. Human beings do calculations on their own. But
computer is a dumb machine and it has to be given proper instructions to carry out its calculation. This
is why we should know how a computer works.
Definition of Computer
Computer is an electronic device, which can do arithmetic calculations faster. For a common man
computer is simply a calculator, which works automatic and quite fast. For a person who knows much
about it, computer is a machine capable of solving problems and manipulating data. It accepts data,
processes the data by doing some mathematical and logical operations and gives us the desired output.
Therefore, we may define computer as a device that transforms data. 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. Computer can also be defined
in terms of its functions. It can accept, store and process data in desired manner, retrieve the stored
data as and when required and print the result in desired format. You will know more about these
functions as you go through the later lessons. The figure shown below depicts a personal computer.
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Personal Computer
Characteristics Of Computer
Let us identify the major characteristics of computer. These can be discussed under the headings of
speed, accuracy, diligence, versatility and memory.
Speed
As you know computer can work very fast. It takes only few seconds for calculations that we take
hours to complete. Suppose you are asked to calculate the average monthly income of one thousand
employees in your organization. For this purpose, you have to add income of all employees on a day-
to-day basis and find out the average for each one of them. How long will it take for you to do this?
One day, two days or one week? Do you know your small computer can finish this work in few
seconds? The weather forecasting that you see every day on TV is the results of compilation and
analysis of huge amount of data on temperature, humidity, pressure, etc. of various places on computers.
It takes few minutes for the computer to process this huge amount of data and give the result.
You will be surprised to know that computer can perform millions (1,000,000) of instructions and even
more per second. Therefore, we determine the speed of computer in terms of microsecond (10-6 part
of a second) or nano-second (10-9 part of a second). From this you can imagine how fast your computer
performs work.
Accuracy
Suppose some one calculates faster but commits a lot of errors in computing. Such result is useless.
There is another aspect. Suppose you want to divide 15 by 7. You may work out up to 2 decimal
places and say the dividend is 2.14. I may calculate up to 4 decimal places and say that the result is
2.1428. Some one else may go up to 9 decimal places and say the result is 2.142857143. Hence, in
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addition to speed, the computer should have accuracy or correctness in computing.
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 computer. The errors in computer
are due to human and inaccurate data.
Diligence
A computer is free from tiredness, lack of concentration, fatigue, etc. It can work for hours without
creating any error. If millions of calculations are to be performed, a computer will perform every
calculation with the same accuracy. Due to this capability it overpowers human being in routine type of
work.
Versatility
It means the capacity to perform completely different type of work. You may use your computer to
prepare payroll slips. Next moment you may use it for inventory management or to prepare electric
bills.
Power of Remembering
Computer has the power of storing any amount of information or data. Any information can be stored
and recalled as long as you require it, for any numbers of years. It depends entirely upon you how
much data you want to store in a computer and when to lose or retrieve these data.
No IQ
Computer is a dumb machine and it cannot do any work without instruction from the user. It performs
the instructions at tremendous speed and with accuracy. It is you to decide what you want to do and in
what sequence. So a computer cannot take its own decision as you can.
No Feeling
It does not have feelings or emotion, taste, knowledge and experience. Thus it does not get tired even
after long hours of work. It does not distinguish between users.
Storage
The Computer has an in-built memory where it can store a large amount of data. You can also store
data in secondary storage devices such as floppies, which can be kept outside your computer and can
be carried to other computers.
1.2 CLASSIFICATION AND APPLICATIONS
Computers can be classified as per the type of data processed by them or as per size, cost and
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configuration. As the size and cost of computers is being reduced continuously and configuration is
improving at very fast pace, later classification has become important.
1.2.1 Classification of Computers based on Data type
This classification of Computers is based on the type of data they are designed to process. Data may
be obtained either as a result of counting or through the use of same measuring instrument. Data that
are obtained by counting are called discrete data. Examples of discrete data are total number of
students in a classroom. This type of data is processed by digital computers. Data that must be
obtained through measurement are called continuous data for example speed of an automobile measure
by speedometer or the temperature of a patient as measured by a thermometer. Continuous data can
be easily processed by analog computer.
Digital Computer
A digital computer is a counting device that operates on discrete data. It operates by directly counting
members (or digits) that represent numerals, letters or other special symbols. Just as digital watches
directly count off the seconds and minutes in an hour, digital processors also count discrete values to
achieve the desired output results.
In contrast to digital processors, however, there are also analog machines that do not compute directly
with numbers. They deal with variables that are measured along a continuous scale and are recorded to
some predetermined degree of accuracy. Temperature for example may be measured to the nearest
tenth of a degree on the Celsius scale, voltage may be measured to the nearest of hundredth of a volt.
A service station petrol pump may contain analog processor.
Analog Computer
Analog computers may be accurate to within 0.1 percent of the correct value or upto limited number of
decimal places (e.g. 2-3). But digital computers can obtain degree of accuracy upto required number
simply by calculating additional places to the right of the decimal point (e.g. 10-20). For example, a
pi(p) has a value of 3.1416. Actually the true value of pi is 3.14159.... (this number could go on for
pages). For more accuracy larger number of digits are required after decimal place.
Desirable features of analog and digital machines are sometimes combined to create a hybrid computing
system in a hospital intensive-care unit, for example analog devices may measure a patient’s heart
function, temperature and other vital signs. These measurements may then be convicted into members
and supplied to a digital component in the system.
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Hybrid Computers
Various specifically designed computers are with both digital and analog characteristics combining the
advantages of analog and digital computers when working as a system. Hybrid computers are being
used extensively in process control system where it is necessary to have a close representation with the
physical world.
The hybrid system provides the good precision that can be attained with digital computers and the
greater control that is possible with analog computers, plus the ability to accept the input data in either
form.
1.2.1 Classification of computers based on their size, cost & configuration
In this category computers are classified as microcomputers, mini computers, mainframe computers,
home computers and super computers.
Micro Computers:
A. Microcomputer is the smallest general-purpose processing system that can execute program
instructions to perform a wide variety of tasks. These systems are typically used by home and school
users. They can be divided into different types:
1. Desktop computers - These would typically be supplied with the
computer itself (complete with hard disk drive and floppy disk drive) and peripherals
such as a screen, a mouse, a keyboard and a CD or DVD drive.
a. Advantages: Relatively cheap and easy to add expansion cards to.
b. Disadvantages: Can take up a lot of space and are not easily moved.
2. Notebooks (laptops) - These are small (typically 30cm x 20cm), light and easy to carry.
The screen is on the inside top flap which hinges open to show the keyboard and mouse
controls. They are designed to run on rechargeable batteries or the mains and can contain
many of the features available on a desktop computer. Touch pads or a button are usually
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