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es s Pr sit y iv er O xf or d Un Assistant Professor, Department of Computer Science Shyama Prasad Mukherji College for Women University of Delhi © Oxford University Press. All rights reserved. Oxford University Press is a department of the University of Oxford. It furthers the University’s objective of excellence in research, scholarship, and education by publishing worldwide. Oxford is a registered trade mark of Oxford University Press in the UK and in certain other countries. Published in India by Oxford University Press YMCA Library Building, 1 Jai Singh Road, New Delhi 110001, India © Oxford University Press 2014 The moral rights of the author/s have been asserted. First published in 2014 Pr es s All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means, without the prior permission in writing of Oxford University Press, or as expressly permitted by law, by licence, or under terms agreed with the appropriate reprographics rights organization. Enquiries concerning reproduction outside the scope of the above should be sent to the Rights Department, Oxford University Press, at the address above. sit y You must not circulate this work in any other form and you must impose this same condition on any acquirer. iv er ISBN-13: 978-0-19-945272-9 ISBN-10: 0-19-945272-5 O xf or d Un Typeset in Times New Roman by Cameo Corporate Services Limited, Chennai Printed in India by Rajkamal Electric Press, Kundli, Haryana © Oxford University Press. All rights reserved. O xf or d Un iv er sit y Pr es s I dedicate this book to my family and my uncle Mr B. L. Thareja © Oxford University Press. All rights reserved. Features of 5 1 Boolean Algebra and Logic Gates Introduction to Computers 2 6 Input and Output Devices Comprehensive coverage The book provides a comprehensive coverage of topics ranging from fundamental concepts of computers to emerging computer technologies. Computer Software 3 7 Computer Memory and Processors Operating Systems 4 Computer d Notes These elements highlight the important terms and concepts discussed in each chapter. A minterm is a product term, but a product term may or may not be a minterm. SUMMARY O xf Summary A list of key topics at the end of each chapter helps the readers to revise all the important concepts explained in the chapter. • When computers were ﬁrst used for business • • • • GLOSSARY • Input device A device used to feed data and instructions into the computer. Optical character recognition The process of converting printed material into text or word processing ﬁles that can be easily edited and stored. Optical devices Devices that use light as a source of input for detecting or recognizing different objects. Optical mark recognition The process of electronically extracting data from marked ﬁelds, such as Output Fig. 8.7 Interpreter or Note Interpreter software iv er Source file Un Illustrations As many as 380 illustrations are included to support the explanations, which help clarify the concepts in a clear manner. sit y Pr es s Number Systems and Computer Codes checkboxes and ﬁll-in ﬁelds, on printed forms. Output device A device that is used to present information from the computer to the user. Pointing device A device that enables the users to easily control the movement of the pointer to select items on a display screen, to select commands from the command menu, to draw graphs, etc. Printer A device that takes the text and graphics information obtained from a computer and prints it on paper. applications, a group of related records was stored in a ﬁle. An effective database system comprises four main components—data, hardware, software, and users. The main objective of the DBMS is to help users to efﬁciently retrieve data from the database. The DBA enforces data abstraction in database systems by deﬁning data views at three levels—external view, logical view, and internal (or physical) view. A database model describes three things—the data, the relationships that exist between the data, and the constraints on that data. The hierarchical data model supports one-to-n mapping, whereas the network model supports many-to-many data mapping. • The data deﬁnition module provides functions to deﬁne the structure of the data, and the data manipulation module provides functions to perform operations such as inserting, searching, and deleting data in the database. • The query processor accepts users’ queries and transforms them into a series of low-level instructions. The report writer utilizes the output of query execution to display it in a format that is easy to understand and interpret format. • Database users can easily retrieve data from a database using SQL. The SELECT statement of SQL allows users to query or retrieve data from a table in the database. Glossary All chapters provide a list of key terms along with their deﬁnitions for a quick recapitulation of important terms. © Oxford University Press. All rights reserved. the Book Objective Questions Comprehensive exercises are provided at the end of each chapter to facilitate revision. Answers to these questions are provided in the Appendix at the end of book. Fill in the Blanks 1. ________ tells the hardware what to do and how to do it. 2. The hardware needs a ________ to instruct what has to be done. 3. The process of writing a program is called ________. 4. ________ is used to write computer software. 5. ________ transforms the source code into binary language. 6. ________ allows a computer to interact with additional hardware devices such as printers, scanners, and video cards. 7. ________ helps in coordinating system resources and allows other programs to execute. 8. ________ provides a platform for running application software. 9. ________ can be used to encrypt and decrypt ﬁles. 10. ________ is a software package that enables its users to create, edit, print, and save documents for future retrieval and reference. 11. ________ is used by architects and engineers to create architectural drawings. Multiple Choice Questions 1. BIOS is stored in ________. (a) RAM (b) ROM (c) Hard disk (d) None of these 2. The symbolic language among the following is: (a) Machine language (b) C (c) Assembly language (d) All of these 3. The language that does not need any translator is: (a) Machine language (b) 3GL (c) Assembly language (d) 4GL 4. Choose the odd one out. (a) Compiler (c) Assembler (b) Interpreter (d) Linker 5. An example of utility software is: (a) Word processor (b) Anti-virus (c) Desktop publishing tool p p g y 8. Give some examples of computer software. 9. Differentiate between the source code and the object code. 10. Why are compilers and interpreters used? 11. Is there any difference between a compiler and an interpreter? 12. What is application software? Give examples. 13. What is BIOS? 14. What do you understand by utility software? Is it necessary to have it? 15. Differentiate between syntax errors and logic errors. 16. Can a program written in a high-level language iv er Review Questions Numerous review questions at the end of every chapter to test the readers’ understanding of the concepts learned. O xf or d Review Questions 1. What is Boolean algebra? Give its applications. 2. Explain Boolean laws using Venn diagrams. 3. Draw the Venn diagram for the Boolean expression (A U B)′ ∩ C. 4. Explain the utility of a truth table as a visualization tool in Boolean algebra. 5. Draw the truth table for Z = A ∩ (B U C). 6. Prove the validity of the consensus and absorption laws. 7. How are Boolean functions represented? 8. Differentiate between a minterm and a maxterm. 9. Give the minterms and maxterms for the Boolean AND operation. 10. Explain the steps to convert an SOP expression into its canonical SOP form with the help of an example. 11. Convert F(A, B, C) = A′B + B′C + A′C to the canonical SOP form. 12. Explain the steps to convert a POS expression into the canonical POS form with the help of an example. 13. Convert F(A, B, C) = (A′ + B′)(B′ + C) to the canonical POS form. 14. What are logic diagrams? How are they useful? 15. Draw the logic diagram for the Boolean expression Y = (A·B + C′·D) + (A′ + D). 16. Implement the following expressions using logic gates: (a) Y = (A·B) + (C·D)·E (b) Y = A + (C + D)·(A·B) 17. Implement the expressions given in Question 16 using NAND gates. 18. Implement the expressions given in Question 16 using NOR gates. 19. Write a short note on K-maps. 20. Draw a K-map and simplify the Boolean expression given by f(x, y, z) = Σm(0, 2, 3, 4, 6, 7). 21. What are adder circuits? Explain the different types of adder circuits. 22. Explain the use of ﬂip-ﬂops in digital circuits. 23. Write a short note on the different types of ﬂipﬂops. 24. Differentiate between simple and clocked ﬂipﬂops. Un 7. In a K-map, groups of cells are formed such that they do not include a cell with the value 1. 8. Usually, 64-bit ripple carry adders take 200–400 nanoseconds to generate the ﬁnal sum. 9. The SR ﬂip-ﬂop is a reﬁnement of the JK ﬂip-ﬂop. 10. When J = K = 1, the ﬂip-ﬂop switches to the complement state. sit y Pr es s State True or False 1. Computer hardware is constituted by its physical components. 2. Computer hardware cannot think and make decisions on its own. 3. Software is a set of instructions arranged in a sequence to guide the computer to ﬁnd a solution for a given problem. 4. Word processor is an example of educational software. 5. Desktop publishing system is a type of system software. 21. In the ________ phase, a plane of actions is made. 22. Algorithms and ﬂowcharts are designed in the ________ phase. Lab Activities Lab Activities These step-by-step tutorials help the readers to learn diﬀerent applications such as Ms Word, Ms PowerPoint, and Ms Excel, as well as to access and use the Internet and to add diﬀerent devices to a computer. 3 Working with the Internet ACTIVITY 1 CREATING A NEW GMAIL ACCOUNT Step 1: Open any web browser such as Internet Explorer, Netscape Navigator, Google Chrome, or Mozilla Firefox. Step 2: In the address bar, type www.gmail.com. You will get the page shown in Figure A3.1. Step 3: Click on the Create an account button (indicated by the arrow in the figure). © Oxford University Press. All rights reserved. Step 4: Fill your details in the form (Figure A3.2) provided and click on Next step. Step 5: You will be asked to enter your phone number for verification. Enter the number and click on Continue. Step 6: Your Gmail account is now created. Click on Show me my account. Your mailbox will be displayed as shown in Figure A3.3. Now you can send emails, photographs, files, or any other document to your friend To read an email simply click on Preface questions to enable students to check their understanding of the concepts • Includes a list of key terms at the end of each chapter that facilitates revision of important topics learned • Highlights important concepts in the form of Notes • Includes a separate section on Lab Activities ORGANIZATION OF THE BOOK es s The book is organized into twelve chapters and seven lab activities. Pr Chapter 1 provides an introduction to computers. The chapter explains the applications, classifications, and the basic organization of the computer system. sit y Chapter 2 gives a detailed description of the different types of input and output devices. Chapter 3 explains the significance of memory hierarchy and discusses the different types of primary, secondary, and tertiary memory that are widely used to store data. It also discusses the basic processor architecture (including RISC and CISC) and the instruction set. ABOUT THE BOOK Un iv er Today computers are used in almost every field, starting from education, medical, banking, construction, communication; to defence, transportation, sports, manufacturing, marketing, etc. The list is literally unending. In a world driven by Information Technology (IT), it is difficult to fathom a field that does not make use of computers! The use of computers has become so widespread that almost every electrical and electronic device (such as a washing machine or an air conditioner) has a small embedded computer within it. In India, computers are now a part of millions of households. Even the mobile phones that we use are smartphones (phones with computing technology) that are connected to the Internet. Information technology has revolutionized our lifestyle. Online banking and shopping are being preferred. Employees can work from home to save time commuting to their offices. Therefore, in today’s scenario learning computers is not just a prerogative of students pursuing a career in engineering and technology; it is a must for everyone. Computing skills help one to be more productive and efficient. Therefore, a basic knowledge of computers and its technology will definitely pay rich dividends in the future. O xf or d Fundamentals of Computers is an ideal textbook for learning computers on one’s own. The book covers both the basic concepts of computers such as organization, architecture, input and output devices, and primary and secondary memory as well as advanced topics including operating systems, computer networks, and databases. The book also offers step-by-step tutorials to learn applications such as MS Word, MS PowerPoint, and MS Excel. Since the use of computer is no longer confined to engineers and scientists, the book can be used by a broad spectrum of students, ranging from students enrolled in elementary courses on Information Technology and Computer Sciences to those in professional courses such as BTech, BBA, BCA, and MCA. It would also be a valuable reference for diploma courses and courses taught at the polytechnic level. KEY FEATURES • Provides a comprehensive coverage of important topics ranging from basics of computers to emerging technologies • Supports numerous well-labelled diagrams in all chapters • Provides a wealth of solved examples and chapter-end exercises in the form of objective type questions and review Chapter 4 explains the binary number system representation and discusses the binary, octal, and hexadecimal number systems. The chapter enables the reader to perform arithmetic operations such as addition, subtraction, multiplication, and division on binary numbers. Important binary codes such as ASCII, EBCDIC, Excess 3, and Gray Codes are also discussed in the chapter. Chapter 5 discusses the concepts of digital computing systems such as Boolean Algebra, Boolean functions, Boolean expressions, logic gates, adder circuits, and flip flops. Chapter 6 is about computer software. It brings out the difference between application and system software. The chapter discusses the different types of system software and application software packages that are widely used. Chapter 7 discusses operating systems and their evolution. It also explains the different jobs that an operating system performs and discusses some commonly used operating systems such as Windows, Unix, Linux, and DOS. Chapter 8 explains algorithms, psuedocodes, and flowcharts which are considered to be the first step towards writing a computer program. The chapter introduces the concept of programming languages and their evolution through years. The chapter also discusses different paradigms of programming and discuses some popular programming languages © Oxford University Press. All rights reserved. viii Preface such as C, C++, Java, Pascal, BASIC, FORTRAN, and LISP. Lab Activities will prove very beneficial for getting a hands-on experience while working with computer systems. Chapter 9 gives a description of traditional fileoriented approach of data management and introduces the concept of databases, their architecture, models, and components. Appendix at the end of the book provides answers to objective questions given in each chapter. Chapter 10 discusses computer networks, their applications, the connecting media, data transmission mode, network topologies, area networks, and the devices used to form a network. It also details data switching and multiplexing techniques. The mammoth task of writing this book required the help and support of many individuals. Fortunately, I have had the wholehearted support of my family and friends. I would like to specially thank my father Mr Janak Raj Thareja and mother Mrs Usha Thareja, my brother Pallav, and sisters Kimi and Rashi who are a source of abiding inspiration and divine blessings for me. I am especially thankful to my son Goransh who has been very patient and cooperative in letting me realize my dreams. My sincere thanks go to my uncle Mr B.L. Thareja for his inspiration and guidance in writing this book. Finally, I would like to thank the editorial team at Oxford University Press India for their help and support. es s Pr O xf or d Un iv er Chapter 12 introduces new and emerging technologies such as peer-to-peer computing, distributed computing, cloud computing, grid computing, on-demand computing, Bluetooth networks, and wireless networks. sit y Chapter 11 introduces the concept and evolution of the Internet. It discusses different services provided by the Internet, threats to security, and counter measures to be adopted for ensuring privacy and security over the Internet. Acknowledgements © Oxford University Press. All rights reserved. Reema Thareja Brief Contents Features of the Book iv Preface vii Detailed Contents xi 1. Introduction to Computers ............................................................................................................................... 1 2. Input and Output Devices .............................................................................................................................. 14 3. Computer Memory and Processors ................................................................................................................ 30 es s 4. Number Systems and Computer Codes ......................................................................................................... 48 5. Boolean Algebra and Logic Gates ................................................................................................................. 62 Pr 6. Computer Software ........................................................................................................................................ 84 7. Operating Systems ......................................................................................................................................... 100 sit y 8. Introduction to Algorithms and Programming Languages ............................................................................ 127 9. Database Systems .......................................................................................................................................... 149 iv er 10. Computer Networks ....................................................................................................................................... 161 11. The Internet .................................................................................................................................................... 182 Un 12. Emerging Computer Technologies ................................................................................................................. 195 O xf or d Lab Activities 1: Understanding Computer Hardware 217 2: Adding Devices to a Computer 223 3: Working with the Internet 227 4: Working with Microsoft Word 232 5: Working with Microsoft Excel 240 6: Working with Microsoft Access 249 7: Working with MS Office 262 Appendix: Answers to Objective Questions 266 Index 273 © Oxford University Press. All rights reserved. es s Pr sit y iv er Un d or O xf © Oxford University Press. All rights reserved. Detailed Contents 4.3 Octal Number System 52 4.3.1 Converting an Octal Number into Decimal Form 52 4.3.2 Converting a Decimal Number into Octal Form 53 4.3.3 Converting an Octal Number into Binary Form 53 4.3.4 Converting a Binary Number into Octal Form 53 4.4 Hexadecimal Number System 53 4.4.1 Converting a Hexadecimal Number into Decimal Form 54 4.4.2 Converting a Decimal Number into Hexadecimal Form 54 4.4.3 Converting a Hexadecimal Number into Binary Form 54 4.4.4 Converting a Binary Number into Hexadecimal Form 54 4.4.5 Converting a Hexadecimal Number into Octal Form 54 4.4.6 Converting an Octal Number into Hexadecimal Form 55 5.9 Simplification of Boolean Expressions Using Karnaugh Map 5.10 Adder Circuits iv er Un 62 62 63 64 64 Identity Law 64 Idempotency Law 64 Complement Law 64 Involution Law 64 Commutative Law 65 Associative Law 65 Distributive Law 65 Absorption Law 66 Consensus Law 66 De Morgan’s Laws 66 84 6.1 Introduction to Computer Software 6.2 Classification of Computer Software 6.3 System Software 6.4 6.5 6.6 6.7 6.8 d or O xf Boolean Algebra Venn Diagrams Truth Tables Basic Laws of Boolean Algebra 5.4.1 5.4.2 5.4.3 5.4.4 5.4.5 5.4.6 5.4.7 5.4.8 5.4.9 5.4.10 Computer Software 84 85 85 Pr 55 56 80 es s 6. 4.8.1 ASCII Code 58 4.8.2 Extended Binary Coded Decimal Interchange Code 58 4.8.3 Excess-3 Code 59 4.8.4 Other Weighted Codes 59 4.8.5 Gray Code 59 4.8.6 Unicode 59 5.1 5.2 5.3 5.4 77 SR Flip-flop 78 JK Flip-flop 78 T Flip-flop 79 D Flip-flop 79 5.12 Applications of Flip-Flops 57 58 Boolean Algebra and Logic Gates 73 75 5.10.1 Half Adder 75 5.10.2 Full Adder 76 5.10.3 Ripple Carry Adder 76 5.11.1 5.11.2 5.11.3 5.11.4 4.6.1 Sign-and-magnitude 56 4.6.2 One’s Complement 57 4.6.3 Two’s Complement 57 5. 71 5.8.1 NAND Universal Gate 71 5.8.2 NOR Universal Gate 72 5.11 Flip-Flops 4.5 Working with Fractions 4.6 Signed Number Representation in Binary Form 4.7 BCD Code 4.8 Other Codes 5.8 Universal Gates sit y xii 7. 6.3.1 6.3.2 6.3.3 6.3.4 Computer BIOS and Device Drivers 85 Operating System 86 Utility Software 86 Compiler, Interpreter, Linker, and Loader 87 Application Software Firmware Middleware Acquiring Computer Software Design and Implementation of Correct, Efficient, and Maintainable Programs Operating Systems 7.1 Introduction 7.2 Evolution of Operating Systems 7.3 Process Management 7.3.1 7.3.2 7.3.3 7.3.4 7.3.5 7.3.6 87 94 94 95 96 100 100 102 105 Process Control Block 105 Process Operations 106 Processes Scheduling 106 Process Synchronization 107 Interprocess Communication 107 Deadlock 107 7.4 Memory Management 108 7.4.1 Multiple Partition Allocation 108 7.4.2 Paging 109 7.4.3 Segmentation 109 7.5 File Management 5.5 Representations of Boolean Functions 67 5.5.1 Minterm 67 5.5.2 Maxterm 68 5.6 Logic Gates 5.7 Logic Diagrams and Boolean Expressions 68 70 7.5.1 7.5.2 7.5.3 7.5.4 111 Data Hierarchy 111 File Attributes 111 Basic File Operations 112 File Organization 112 7.6 Device Management © Oxford University Press. All rights reserved. 115 Detailed Contents 7.7 Security Management 7.8 Command Interpreter 7.9 Popular Operating Systems 9.5.1 9.5.2 9.5.3 9.5.4 Introduction to Algorithms and Programming Languages 127 8.1 Algorithm 8.2 Control Structures Used in Algorithms 127 127 8.2.1 Sequence 127 8.2.2 Decision 128 8.2.3 Repetition 128 128 129 131 8.5.1 Keywords Used while Writing Pseudocodes 131 132 133 iv er 8.6 Programming Languages 8.7 Generations of Programming Languages First Generation: Machine Language 133 Second Generation: Assembly Language 134 Third Generation: High-level Language 135 Fourth Generation: Very High-level Languages 137 8.7.5 Fifth-generation Programming Language 138 161 161 162 Twisted-pair Wires 162 Coaxial Cables 162 Fibre Optic Cables 162 Wireless Technologies 163 d or 8.8 Categorization of High-level Languages 138 O xf 8.9 Some Popular High-level Languages 142 BASIC 142 FORTRAN 143 Pascal 143 C 143 C++ 143 Java 144 LISP 144 10.5 Data Switching 10.7.1 10.7.2 10.7.3 10.7.4 10.7.5 Database Systems 10.8.1 10.8.2 10.8.3 10.8.4 10.8.5 144 149 9.1 File-Oriented Approach 9.2 Database-oriented Approach 149 150 9.2.1 Components of Database System 151 9.2.2 Advantages of Database Approach 152 9.2.3 Disadvantages of Database Approach 152 168 10.5.1 Circuit Switching 168 10.5.2 Message Switching 168 10.5.3 Packet Switching 169 171 Local Area Network 172 Wide Area Network 172 Metropolitan Area Network 173 Campus/Corporate Area Network 173 Personal Area Network 174 10.9 Networking Devices 10.9.1 10.9.2 10.9.3 10.9.4 10.9.5 10.9.6 10.9.7 169 170 Bus Topology 170 Star Topology 170 Ring Topology 171 Mesh topology 171 Hybrid Topology 171 10.8 Types of Network 8.10 Factors Affecting Selection of Programming Language 166 10.4.1 Techniques of Multiplexing 166 10.6 Data Routing Techniques 10.7 Network Topologies Unstructured Programming 138 Structured Programming Language 138 Logic-oriented Programming Language 139 Object-oriented Programming 140 163 10.3.1 Simplex, Half-duplex, and Full-duplex Connections 163 10.3.2 Serial and Parallel Transmissions 164 10.3.3 Synchronous and Asynchronous Data Transmission Modes 165 10.4 Data Multiplexing Un 8.7.1 8.7.2 8.7.3 8.7.4 10.2.1 10.2.2 10.2.3 10.2.4 10.3 Data Transmission Mode 8.5 Pseudocode 9. Computer Networks 156 158 Pr 8.4.1 Significance of Flowcharts 129 8.4.2 Advantages 130 8.4.3 Limitations 131 8.9.1 8.9.2 8.9.3 8.9.4 8.9.5 8.9.6 8.9.7 9.6 Components of Database Management Systems 9.7 Retrieving Data Through Queries 10. 152 153 154 Hierarchical Model 154 Network Model 154 Relational Model 155 Object-oriented Data Model 156 10.1 Introduction to Computer Networks 10.2 Connecting Media 8.3 Some More Algorithms 8.4 Flowcharts 8.8.1 8.8.2 8.8.3 8.8.4 9.3 Database Views 9.4 Three-schema Architecture 9.5 Database Models es s 8. Microsoft DOS 119 Microsoft Windows 120 Unix 121 Linux 122 9.2.4 Applications of Database Systems 152 sit y 7.9.1 7.9.2 7.9.3 7.9.4 117 117 119 xiii 174 Hub 174 Repeater 174 Switch 174 Bridge 174 Router 175 Gateway 175 Network Interface Card 175 10.10 Open System Interconnection Model © Oxford University Press. All rights reserved. 176 Detailed Contents The Internet 11.1 Internet 182 12.3 Grid Computing 11.1.1 History 182 11.2 Internet Services Electronic Mail 183 File Transfer Protocol 183 Chatting 184 Internet Conferencing 184 Electronic Newspaper 184 World Wide Web 185 Online Shopping 185 Search Engine 186 12.4 Cloud Computing 187 188 Dial-up Connection 188 Integrated Services Digital Network 188 Leased Connection 188 Digital Subscriber Line Connection 188 Cable Modem Connection 188 Very Small Aperture Terminal 189 11.5 Internet Security 189 195 196 207 12.8.1 Bluetooth Piconets 208 12.8.2 Avoiding Interference in Bluetooth Devices 209 12.8.3 Bluetooth Security 209 12.8.4 Differences between Bluetooth and Wireless Networks 210 12.9 Artificial Intelligence Un 12.1 Distributed Networking 12.2 Peer-to-peer Computing 195 202 204 204 Wireless Network Operation 205 Types of Wireless Networks 206 Security in Wireless Networks 206 Limitations of Wireless Networks 207 12.8 Bluetooth iv er Emerging Computer Technologies 12.5 Utility Computing 12.6 On-demand Computing 12.7 Wireless Network 12.7.1 12.7.2 12.7.3 12.7.4 11.5.1 Threats to Internet Security 189 11.5.2 Preventive Measures 192 12. 199 12.4.1 Characteristics of Cloud Computing Systems 200 12.4.2 Cloud Computing Services 200 12.4.3 Cloud Computing Architecture 201 12.4.4 Cloud Computing Applications 202 12.4.5 Cloud Computing Concerns 202 11.3 Internet Glossary 11.4 Types of Internet Connections 11.4.1 11.4.2 11.4.3 11.4.4 11.4.5 11.4.6 198 12.3.1 Components of Grid Computing 199 12.3.2 Applications of Grid Computing 199 183 Pr 11.2.1 11.2.2 11.2.3 11.2.4 11.2.5 11.2.6 11.2.7 11.2.8 12.2.1 Categorization of Peer-to-peer Systems 196 12.2.2 Applications and Considerations of Peer-to-peer Networks 197 182 es s 11. sit y xiv O xf or d Lab Activities 1: Understanding Computer Hardware 217 2: Adding Devices to a Computer 223 3: Working with the Internet 227 4: Working with Microsoft Word 232 5: Working with Microsoft Excel 240 6: Working with Microsoft Access 249 7: Working with MS Office 262 Appendix: Answers to Objective Questions 266 Index 273 © Oxford University Press. All rights reserved. 210 1 es s Introduction to Computers sit y Pr Learning Objectives WHAT IS A COMPUTER? or 1.1 d Un iv er In this chapter, we will learn the deﬁnition and various characteristics of computers and see how they have evolved from big machines used only for scientiﬁc purposes to small devices that can even be used in a wristwatch. We will read about the different types of computing devices, the basic organization of a computing device, and see how computers are used in different areas of our day-to-day lives. O xf A computer, in simple terms, can be defined as an electronic device that is designed to accept data, perform the required mathematical and logical operations at high speed, and output the result. We all have seen computers in our homes, schools, and colleges. In fact, in today’s scenario, we find computers in most aspects of our daily lives. For some of us, it is hard to even imagine a world without them. In the past, computers were extremely large in size and often required an entire room for installation. These computers consumed enormous amounts of power and were too expensive to be used for commercial applications. Therefore, they were used only for limited tasks, such as computing trajectories for astronomical or military applications. However, with technological advancements, the size of computers became smaller and their energy requirements reduced immensely. This opened the way for adoption of computers for commercial purposes. These days, computers have become so prevalent in the market that all interactive devices such as cellular phones, global positioning system (GPS) units, portable organizers, automatic teller machines (ATMs), and gas pumps, work with computers. 1.2 CHARACTERISTICS OF COMPUTERS We have seen that a computer is an electronic device that performs a function based on a given set of instructions known as a program. A computer accepts data, processes it, and produces information (see Figure 1.1). Here, data refers to some raw facts or figures, and information implies the processed data. For example, if 12-12-92 is the date of birth of a student, then it is data (a raw fact/figure). However, when we process this data (subtract it from the present date) and say that the age of the student is 18 years, then the outcome is information. Data Process Information Fig. 1.1 Functions of computers Today, computers have become a crucial part of our everyday lives, and we need computers just like we need the television, telephones, or other electronic devices at home. Computers are basically meant to solve problems quickly and accurately. The important characteristics of a computer (refer to Figure 1.2) are discussed in the following text. © Oxford University Press. All rights reserved. Fundamentals of Computers Speed Computers can perform millions of operations per second, which means that data that may otherwise take many hours to process is output as information in the blink of an eye. The speed of computers is usually given in nanoseconds and picoseconds, where 1 nanosecond = 1 × 10−9 seconds and 1 picosecond = 1 × 10−12 seconds. No IQ Although the trend today is to make computers intelligent by inducing artificial intelligence (AI) in them, they still do not have any decision-making abilities of their own. Thus, their IQ level is zero. They need guidance to perform various tasks. Economical Today, computers are considered as short-term investments for achieving long-term gains. Using computers also reduces manpower requirements and leads to an elegant and efficient way of performing various tasks. Hence, computers save time, energy, and money. When compared to other systems, computers can do more work in lesser time. For example, using the conventional mail system to send an important document takes at least two or more days, whereas the same information when sent using the Internet (e-mail) will be delivered instantaneously. O xf or d Un iv er Accuracy A computer is a very fast, reliable, and robust electronic device. It always gives accurate results, provided the correct data and set of instructions are input to it. Hence, in the event of an error, only the user who has fed the incorrect data/program needs be held responsible. This clearly means that the output generated by a computer depends on the given instructions and input data. If the input data is wrong, then the output will also be erroneous. In computer terminology, this is known as garbage-in, garbage-out (GIGO). Automation Besides being very fast and accurate, computers are automatable devices that can perform a task without any user intervention. The user just needs to assign the task to the computer, after which it automatically controls different devices attached to it and executes the program instructions. Diligence Unlike humans, computers never get tired of a repetitive task. It can continually work for hours without creating errors. Even if a large number of executions are needed, each and every execution requires the same duration, and is executed with the same accuracy. Versatile Versatility is the quality of being flexible. Today, computers are used in our daily life in different fields. For example, they are used as personal computers (PCs) for home use, for business-oriented tasks, weather forecasting, space exploration, teaching, railways, banking, medicine, and so on, indicating that computers can perform different tasks simultaneously. On the PC that you use at home, you may play a game, compose and send e-mails, listen to music, etc. Therefore, computers are versatile devices as they can perform multiple tasks of different nature at the same time. Memory Similar to humans, computers also have memory. Just the way we cannot store everything in our memory es s y Speed ty sa til i ac V er ur cc A Fig. 1.2 Characteristics of computers Pr n io Large memory Computers sit y IQ at om Economical t Au Diligence and need secondary media, such as a notebook, to record certain important things, computers also have internal or primary memory (storage space) as well as external or secondary memory. While the internal memory of computers is very expensive and limited in size, the secondary storage is cheaper and of bigger capacity. The computer stores a large amount of data and programs in the secondary storage space. The stored data and programs can be retrieved and used whenever required. Secondary memory is the key for data storage. Some examples of secondary devices include floppy disks, optical disks (CDs and DVDs), hard disk drives (HDDs), pen drives, etc. When data and programs have to be used, they are copied from the secondary memory into the internal memory, often known as random access memory (RAM). The concept of computer memory is discussed in detail in Chapter 4. N o 2 1.3 GENERATIONS OF COMPUTERS The word generation, in general, indicates a state of improvement in the product development process. When applied to computing, it refers to the different advancements of new computer technology. With each new generation of computers, the circuitry becomes smaller and more advanced than that used in the previous generation. The focus of every new generation has been on miniaturization, speed, power, and efficient computer memory. Therefore, each generation of computers is characterized by a major technological development that has drastically changed the way in which computers operate. Consequently, these computing devices have become smaller, cheaper, powerful, efficient, and more reliable. In this section, we will read about the major developments in technology that have led to the devices that we use today. 1.3.1 First Generation (1940–1956): Vacuum Tubes First-generation computers used a very large number of vacuum tubes (as shown in Figure 1.3) for circuitry and magnetic © Oxford University Press. All rights reserved. Introduction to Computers 3 Fig. 1.3 Vacuum tube Fig. 1.4 Transistors sit y Pr es s Input was fed to the second-generation computers using punched cards and output was generated as printouts. While the first-generation computers were programmed using machine language, the second-generation computers moved towards symbolic or assembly languages, which allowed programmers to specify instructions in words. At this time, high-level programming languages such as COBOL, FORTRAN, ALGOL, and SNOBOL were also being developed. Second-generation computers were the first to store instructions in memory, which moved from magnetic drum to magnetic core technology. Secondgeneration computers were first developed for the atomic energy industry. iv er drums for memory. These computers were so big in size that they often required an entire room to be installed. The firstgeneration computers were very expensive and were hence mainly used for scientific purposes. In addition to a large amount of space, they also needed a lot of electricity, and thus generated enormous heat, which was often the cause of malfunctions. First-generation computers could be programmed using machine language, which is the lowest-level programming language, consisting of only 1s and 0s. These computers could solve only one problem at a time. While input to the computer was fed using punched cards and paper tape, the output was generated on printouts. Universal automatic computer (UNIVAC) and electronic numerical integrator and calculator (ENIAC) are prime examples of first-generation computing devices. Moreover, UNIVAC was the first commercial computer delivered to a business client (US Census Bureau in 1951). Un Advantage They were the fastest calculating devices of their time. Advantages • They consumed less electricity and thus generated less heat as compared to the first-generation computers. O xf or d Disadvantages • They were faster, cheaper, smaller, and more reliable than • They generated a lot of heat. their first-generation counterparts. • They consumed a lot of electricity. • They could be programmed using assembly language and • They were very bulky in size. high-level languages. • Vacuum tubes used filaments that had limited life. Since • These computers had faster primary memory and a larger every computer used thousands of vacuum tubes, these computers were frequently down due to hardware failure. • These computers needed constant maintenance because of the low mean time between failures. • These computers had limited commercial use because they were difficult to program. • They were very expensive. secondary memory. Disadvantage Second-generation computers were manufactured using transistors, which had to be assembled manually. This made commercial production of computers difficult and expensive. 1.3.3 Third Generation (1964–1971): Integrated Circuits Second-generation computers were manufactured using tran1.3.2 Second Generation (1956–1963): Transistors sistors (as shown in Figure 1.4), rather than vacuum tubes. Transistors were invented in 1947 but were used for manufacturing computers only in the late 1950s. Transistors were far superior to vacuum tubes. Computers manufactured using transistors were smaller, faster, cheaper, and more energy-efficient and reliable than their first-generation predecessors. Although transistors also generated enormous heat, which subjected the computer to damage, they were far better than vacuum tubes. The development of the integrated circuit (IC), shown in Figure 1.5, was the hallmark of the third-generation computers. Several electronic components such as transistors, resistors, and capacitors were miniaturized and placed on silicon chips, called integrated chips, which drastically increased the speed and efficiency of computers. Integrated chips were smaller, less expensive, more reliable and faster in operation, consumed less power, © Oxford University Press. All rights reserved. 4 Fundamentals of Computers 1.3.4 Fourth Generation (1971–1989): Microprocessors or d Un es s Pr iv er and generated less heat than the components used earlier. The third-generation computers were also much more powerful than their predecessors. These computers had a few megabytes of main memory and magnetic disks that could store a few tens of megabytes of data per disk drive. On the software front, high-level programming languages such as COBOL and FORTRAN were standardized by the American National Standards Institute (ANSI), and were known as ANSI FORTRAN and ANSI COBOL, respectively. Standardization helped these languages to run on any computer that had their respective compiler. In addition to this, some more high-level programming languages such as PL/I PASCAL and BASIC were introduced at this time. Thirdgeneration computers were the first to implement time sharing operating systems. Input to these computers could now be provided using the keyboard and the mouse. In the 1960s, the trend was moving towards small minicomputers that could fit in the corner of a room and be used for business applications. It was during this time that software houses emerged. sit y Fig. 1.5 Integrated circuits The microprocessor launched the fourth generation of computers, with thousands of integrated circuits built onto a single silicon chip. While first-generation computers often filled an entire room, fourth-generation computers, on the contrary, could fit in the palm of the hand. For example, the Intel 4004 chip, developed in 1971, consisted of all the components of the computer (such as the central processing unit, CPU; memory; I/O controls, etc.) on a single chip. During the fourth generation, semiconductor memories that were very fast were used and HDDs also became cheaper, smaller in size, and larger in capacity. For input, floppy disks (in addition to magnetic tapes) were used to port data and programs from one computer to another. During this period, many new operating systems were developed, including MS-DOS, Microsoft Windows, UNIX, and Apple’s proprietary operating system. In 1981, IBM introduced the first PC that was specifically meant for the home user, and in 1984 Apple introduced the Macintosh. As these small computers became more powerful, they could be linked together to form networks, which eventually led to the development of the Internet and other distributed systems. Fourth-generation computers also saw the development of graphical user interfaces (GUIs), the mouse, and handheld devices. GUIs made computers more user-friendly, so that even a non-computer professional could work easily on it. In this period, several word processing packages (to allow easy development of documents), spreadsheet packages (to allow easy manipulation and analysis of data organized in rows and columns), and graphics packages (to easily draw and edit images) were introduced, thereby making computers a powerful tool for everyone. • • • • • O xf Advantages Advantages • These computers were smaller, cheaper, faster, and more • They were faster than second-generation computers and could perform one million transactions per second. They were smaller, cheaper, and more reliable than their predecessors. These computers had faster and larger primary memory and secondary storage. Third-generation computers were widely used for scientific as well as business applications. During this generation of computers, standardization of existing high-level languages and invention of new highlevel languages happened. Third-generation computers could run time sharing operating systems, which allowed interactive use of a computer by one or more users simultaneously, thereby improving the productivity of the users. Disadvantages • These computers were difficult to maintain. • They got heated very quickly. reliable than their predecessors. • They consumed less electricity and generated less heat. • They had faster and larger primary memory and secondary storage. • They could be used as general-purpose computers. • GUIs enabled people to learn to work with computers very easily. Hence, the use of computers both in offices and at homes became widespread. • Networks allowed sharing of resources, thereby enabling efficient utilization of computer hardware and software. Disadvantage They were not intelligent systems. 1.3.5 Fifth Generation (Present and Beyond): Artificial Intelligence Fifth-generation computers are completely based on the new concept of artificial intelligence (AI). Although such © Oxford University Press. All rights reserved. Introduction to Computers 1.4 es s It is in the fifth generation of computing devices that voice recognition systems that can convert spoken sounds into written words have come into existence. Such systems do not understand what they are writing; they simply take dictation. Although there are certain expert systems available today, they have not lived up to the expectations. They are too expensive to produce and are helpful only in special situations. Today, the hottest area of AI is neural networks. Neural network systems are widely being used in different fields such as voice recognition and natural language processing. Fifth-generation languages, commonly known as AI languages, are almost exclusively used for AI applications. The two most common are LISP and Prolog. CLASSIFICATION OF COMPUTERS sit y Pr Computers can be broadly classified into four categories based on their speed, amount of data that they can hold, and price (refer to Figure 1.6). These categories are as follows: • • • • Supercomputers Mainframe computers Minicomputers Microcomputers O xf or d Un iv er computers are still in development, there are certain applications such as voice recognition that are widely being used today. Parallel processing and superconductor technology have made AI a reality. Quantum computation and nanotechnology will radically change the face of computers in the years to come. In the fifth-generation computers, the aim is to develop devices that respond to natural language input and are capable of learning and self-organization. AI touches the following areas, among others: Gaming Computers are programmed to play games such as chess and checkers. More recent examples of such gaming systems include PlayStation by Sony, Xbox 360 by Microsoft, and Wii by Nintendo, all of which use sensor technology to detect players’ movements. Expert systems Computers are programmed to take decisions in real-world situations. For example, some expert systems help doctors in diagnosing the disease, based on patients’ symptoms. Natural languages Computers are programmed to understand and respond to natural human languages. Neural networks Systems are programmed to simulate intelligence by reproducing the physical connections that take place in animal brains. Robotics Computers are programmed to look, listen, and react to other sensory stimuli. The current status is that no computer is able to completely simulate human behaviour. In other words, no computer exhibits complete AI. However, one of the biggest achievements of these computers has been in the field of gaming. For example, in 1997, a computer program defeated the world champion Gary Kasparov in a game of chess. In robotics, computers are widely used in manufacturing and assembly plants for performing certain tasks. However, the tasks that robots can perform are limited as they find it difficult to identify objects based on appearance or feel, and they still move and handle objects clumsily. Natural language programs enable people to interact with computers. Although programming computer systems to understand natural languages has proved to be much more difficult than originally planned for, there are some systems that can translate one human language to another, though they are not as good as human translators. 5 1.4.1 Supercomputers Among the four categories, the supercomputer is the fastest, most powerful, and most expensive computer. Supercomputers were first developed in the 1980s to process large amounts of data and to solve complex scientific problems. Supercomputers use parallel processing technology and can perform more than one trillion calculations in a second. A single supercomputer can support thousands of users at the same time. Such computers are mainly used for weather forecasting, nuclear energy research, aircraft design, automotive design, online banking, controlling industrial units, etc. Some examples of supercomputers are CRAY-1, CRAY-2, Control Data CYBER 205, and ETA A-10. Classification of computers Supercomputers Mainframe computers Dumb terminals Intelligent terminals Minicomputers Microcomputers Desktop PC Laptops Workstations Fig. 1.6 Classification of computers © Oxford University Press. All rights reserved. Handheld devices Network 6 Fundamentals of Computers 1.4.4 Microcomputers Mainframe computers are large-scale computers (but smaller than supercomputers). These are very expensive and need a very large clean room with air conditioning, thereby making them very costly to deploy. As with supercomputers, mainframes can also support multiple processors. For example, the IBM S/390 mainframe can support 50,000 users at the same time. Users can access mainframes by either using terminals or via PCs. There are basically two types of terminals that can be used with mainframe systems that are discussed as follows: Dumb terminals consist of only a monitor and a keyboard (or mouse). They do not have their own CPU and memory and use the mainframe system’s CPU and storage devices. Microcomputers, commonly known as PCs, are very small and cheap. The first microcomputer was designed by IBM in 1981 and was named IBM-PC. Later on, many computer hardware companies copied this design and termed their microcomputers as PC-compatible, which refers to any PC that is based on the original IBM PC design. Another type of popular PC is designed by Apple. PCs designed by IBM and other PC-compatible computers have a different architecture from that of Apple computers. Moreover, PCs and PC-compatible computers commonly use the Windows operating system, while Apple computers use the Macintosh operating system (MacOS). However, IBM and IBM-compatible PCs are more popular than their Apple counterparts. PCs can be classified into the following categories: Intelligent Terminals Desktop PCs In contrast to dumb terminals, intelligent terminals have their own processor and thus can perform some processing operations. However, just like the dumb terminals, they do not have their own storage space. Usually, PCs can be used as intelligent terminals to facilitate data access and other services from the mainframe system. Mainframe computers are typically used as servers on the world wide web. They are also used in large organizations such as banks, airline companies, and universities, where a large number of users frequently access data stored in their databases. IBM is the major manufacturer of mainframe computers. Some examples of mainframe computers include IBM S/390, Control Data CYBER 176, Amdahl 580, etc. A desktop PC is the most popular model of PCs. The system unit of the desktop PC can be placed flat on a desk or table. It is widely used in homes and offices. Pr sit y Laptops Laptops (Figure 1.7) are small microcomputers that can easily fit inside a briefcase. They are very handy and can easily be carried from one place to another. They may also be placed on the user’s lap (thus the name). Hence, laptops are very useful, especially when going on long journeys. Laptops operate on a special battery and do not always have to be plugged in like desktop computers. O xf 1.4.3 Minicomputers or d Un iv er Dumb Terminals es s 1.4.2 Mainframe Computers As the name suggests, minicomputers are smaller, cheaper, and slower than mainframes. They are called minicomputers because they were the smallest computer of their times. Also known as midrange computers, the capabilities of minicomputers fall between mainframe and PCs. Minicomputers are widely used in business, education, hospitals, government organizations, etc. While some minicomputers can be used only by a single user, others are specifically designed to handle multiple users simultaneously. Usually, single-user minicomputers are used for performing complex design tasks. As with mainframes, minicomputers can also be used as servers in a networked environment, and hundreds of PCs can be connected to it. The first minicomputer was introduced by Digital Equipment Corporation (DEC) in the mid 1960s. Other manufacturers of minicomputers include IBM Corporation (AS/400 computers), Data General Corporation, and Prime Computer. Fig. 1.7 Laptop The memory and storage capacity of a laptop is almost equivalent to that of a desktop computer. As with desktop computers, laptops also have HDDs, floppy disk drives, zip disk drives, etc. For input, laptops have a built-in keyboard and a trackball/touchpad, which is used as a pointing device (as a mouse is used for a desktop PC). © Oxford University Press. All rights reserved. Introduction to Computers Workstations are single-user computers that have the same features as PCs, but their processing speed matches that of a minicomputer or mainframe computer. Workstation computers have advanced processors, more RAM and storage capacity than PCs. Therefore, they are more expensive and powerful than a normal desktop computer. Although workstation computers are widely used as powerful single-user computers by scientists, engineers, architects, and graphic designers, they can also be used as servers in a networked environment. Personal digital assistants (PDA) Today, the PDA (shown in Figure 1.8) is among the most popular lightweight mobile devices that are used. A number of PDAs available in the market offer a collection of application software for word processing, spreadsheets, games, etc. PDAs are used to take notes, organize telephone numbers, and store addresses. Some devices also include features that facilitate the users to read e-books on the PDA’s screen. es s Workstations they have small-sized screens and keyboards. These computers are preferred by business travellers and mobile employees such as meter readers and parcel delivery people, whose jobs require them to move from place to place. Some examples of handheld computers are • Personal digital assistant (PDA) • Cellular telephones • H/PC Pro devices Pr Today, laptops have the same features and processing speed as the most powerful PCs. However, a drawback is that laptops are generally more expensive than desktop computers. These computers are very popular among business travellers. O xf or d Un iv er sit y Network Computers Network computers have less processing power, memory, and storage than a desktop computer. These are specially designed to be used as terminals in a networked environment. For example, some network computers are specifically designed to access data stored on a network (including the Internet and intranet). Some network computers do not have any storage space and merely rely on the network’s server for data storage and processing tasks. The concept of network computers had become popular in the mid 1990s when several variations of computers such as Windows terminals, NetPCs, and diskless workstations were widely used. Network computers that are specifically designed to access only the Internet or intranet are often known as Internet PCs or Internet boxes. Some network computers used in homes do not even have a monitor. Such computers may be connected to a television, which serves as the output device. The most common example of a home-based network computer is Web TV, which enables the user to connect a television to the Internet. The Web TV is equipped with a special set-top box that is used to connect to the Internet. The set-top box also provides controls to enable the user to navigate the Internet, send and receive e-mails, and to perform other tasks on the network while watching television. The other reason for the popularity of network computers is that they are cheaper to purchase and maintain than PCs. 7 Handheld Computers The mid 1990s witnessed a range of small personal computing devices that are commonly known as handheld computers, Palmtop computers, or Mini-Notebook computers. These computers are called handheld computers because they can fit in one hand, while users can use the other hand to operate them. Handheld computers are very small in size, and hence Fig. 1.8 Personal digital assistant Many PDAs are web-enabled, which means that such devices enable the users to access the Internet and send/receive e-mails. Similarly, some PDAs also provide telephone capabilities. The primary input device of a PDA is the stylus. A stylus enables the user to interact with the touchscreen to write text or draw figures. It can be used to write notes. Some PDAs also support voice input. Cellular phones These days, cellular phones are webenabled telephones that have features of both analogue and digital devices. Such phones are also known as smart phones because, in addition to basic phone capabilities, they also facilitate the users to access the Internet and send e-mails and faxes. H/PC Pro devices The H/PC Pro device (see Figure 1.9) is based on a new development in handheld technology. The size and features of the H/PC Pro device is more than PDAs but less than that of typical notebook PCs. The H/PC Pro device includes a full-sized keyboard, RAM with very low © Oxford University Press. All rights reserved. Fundamentals of Computers storage capacity, and a slow-speed processor. However, these devices do not have a secondary storage disk. BASIC COMPUTER ORGANIZATION Pr 1.5 A computer is an electronic device that basically performs five major operations: iv er Accepting data or instructions (input) Storing data Processing data Displaying results (output) Controlling and coordinating all operations inside a computer Un • • • • • O xf or d In this section, we will discuss all these functions and see how one unit of a computer interacts with another to perform these operations. Refer to Figure 1.10, which shows the interaction between the different units of a computer system. Data and instructions es s Fig. 1.9 H/PC Pro device Storage It is the process of saving data and instructions permanently in the computer so that they can be used for processing. The computer storage space not only stores the data and programs that operate on that data but also stores the intermediate results and the final results of processing. A computer has two types of storage areas: Primary storage This, also known as the main memory, is the storage area that is directly accessible by the CPU at very high speeds. It is used to store the data and parts of programs, the intermediate results of processing, and the recently generated results of jobs that are currently being worked on by the computer. Primary storage space is very expensive and therefore limited in capacity. Another drawback of main memory is that it is volatile in nature; that is, as soon as the computer is switched off, the information stored gets erased. Hence, it cannot be used as a permanent storage of useful data and programs for future use. An example of primary storage is the RAM. Secondary storage Also known as the secondary memory or auxiliary memory, this is just the opposite of primary memory. It basically overcomes all the drawbacks of the primary storage area. It is cheaper, non-volatile, and used to permanently store data and programs of those jobs that are not being currently executed by the CPU. Secondary memory supplements the limited storage capacity of the primary memory. An example is the magnetic disk used to store data such as C and D drives, for future use. Processing The process of performing operations on the data as per the instructions specified by the user (program) is called processing. Data and instructions are taken from the primary memory and transferred to the arithmetic and logical unit (ALU), which performs all sorts of calculations. The intermediate results of processing may be stored in the main memory, as they might be required again. When the processing completes, the final result is then transferred to the main memory. Hence, the data may move from main memory to the ALU Results multiple times before the processing is over. Output Output is the process of giving the result of data processing to the outside world (external to the computer system). The Flow of data and results are given through output devices such instructions as monitor and printer. Since the computer Control exercised accepts data only in the binary form and by control unit the result of processing is also in the binary form, the result cannot be directly given to the user. The output devices, therefore, convert the results available in binary codes into a human-readable language before displaying it to the user. Control The control unit (CU) is the central nervous system of the entire computer system. It manages and controls all the components of the computer system. The CU decides the manner in which instructions will be executed and operations performed. It takes care of the step-by-step processing of all operations that are performed in the computer. sit y 8 Input Storage Output CPU Control unit Arithmetic and logical unit Fig. 1.10 Block diagram of a computer Input This is the process of entering data and instructions (also known as programs) in to the computer system. The data and instructions can be entered by using different input devices such as keyboard, mouse, scanner, and trackball. Note that computers understand binary language, which consists of only two symbols (0 and 1), so it is the responsibility of the input devices to convert the input data into binary codes. © Oxford University Press. All rights reserved. Introduction to Computers APPLICATIONS OF COMPUTERS In the United States, computers are used by the government for city planning and traffic control. For example, to eliminate the problem of gridlock (when traffic is at total standstill in an area for 15 minutes), a new system has been designed that includes induction loops of wire embedded in the asphalt at many intersections across the city. As cars move over the wires, electrical pulses are counted by a central computer, which translates the pulses into the number of cars. It then converts the number to the rate of flow, and instructs the traffic light when to change. All this information is also used to predict potential gridlock locations and to send additional traffic patrols to problem areas. Legal System Computers are used by lawyers to shorten the time required to conduct legal precedent and case research. Lawyers use computers to look through millions of individual cases and find whether similar or parallel cases have been approved, denied, criticized, or overruled in the past. This enables the lawyers to formulate strategies based on past case decisions. Moreover, computers are also used to keep track of appointments and prepare legal documents and briefs in time for filing cases. O xf or d Un iv er When the first computers were developed, they were used only in the fields of mathematics and science. In fact, the first effective utilization of computers was for decoding messages in military applications. Later on, computers were used in real-time control systems, such as for landing on the moon. However, with the advancement of technology, the cost of computers and their maintenance declined. This opened the way for computers to be extensively used in the business and commercial sector for information processing. Today, computers are widely used in fields such as engineering, health care, banking, education, and so on. Let us discuss how computers are being effectively utilized to perform important tasks. Word processing Word processing software enables users to read and write documents. Users can also add images, tables, and graphs for illustrating a concept. The software automatically corrects spelling mistakes and includes copy– paste features (which is very useful where the same text has to be repeated several times). Internet The Internet is a network of networks that connects computers all over the world. It gives the user access to an enormous amount of information, much more than available in any library. Using e-mail, the user can communicate in seconds with a person who is located thousands of miles away. Chat software enables users to chat with another person in real-time (irrespective of the physical location of that person). Video-conferencing tools are becoming popular for conducting meetings with people who are unable to be present at a particular place. Digital video or audio composition Computers make audio or video composition and editing very simple. This has drastically reduced the cost of equipment to compose music or make a film. Graphics engineers use computers for developing short or full-length films and creating 3D models and special effects in science fiction and action movies. Desktop publishing Desktop publishing software enables you to create page layouts for entire books. After discussing how computers are used in today’s scenario, let us now have a look at the different areas where computers are being widely utilized. Traffic Control es s 1.6 ALU, CU, and CPU are the key functional units of a computer system. Computers are used in government organizations to keep records on legislative actions, Internal Revenue Service records, etc. Pr Note Government sit y Note that the CPU is a combination of the ALU and the CU. The CPU is better known as the brain of the computer system because the entire processing of data is done in the ALU, and the CU activates and monitors the operations of other units (such as input, output, and storage) of the computer system. 9 Retail Business Computers are used in retail shops to enter orders, calculate costs, and print receipts. They are also used to keep an inventory of the products available and their complete description. Sports In sports, computers are used to compile statistics, identify weak players and strong players by analysing statistics, sell tickets, create training programmes and diets for athletes, and suggest game plan strategies based on the competitor’s past performance. Computers are also used to generate most of the graphic art displays flashed on scoreboards. Television networks use computers in the control room to display action replays and insert commercial breaks as per schedule. Moreover, companies manufacturing sports shoes such as Nike use computers for designing footwear. They calculate stress points and then create the style and shape that offer maximum support for the foot. In addition, there are simulation software packages available that help a sportsperson to practice his or her skills as well as identify flaws in the technique. Music All computers today have musical instrument digital interface (MIDI) facility, which links musical instruments to a PC, thereby enabling the computer to generate a variety of sounds. © Oxford University Press. All rights reserved. 10 Fundamentals of Computers Moreover, the background music in movies, TV shows, and commercials are all generated electronically using computers. proximity to the fault, soil type, size, shape, and construction material. Movies Astronomy Computers are used to create sets, special effects, animations, cartoons, imaginary characters, videos, and commercials. Spacecrafts are usually monitored using computers that not only keep a continuous record of the voyage and of the speed, direction, fuel, and temperature, but also suggest corrective action if the vehicle makes a mistake. The remote stations on the earth compare all these quantities with the desired values, and in case these values need to be modified to enhance the performance of the spacecraft, signals are immediately sent that set in motion the mechanics to rectify the situation. With the help of computers, all this is done within a fraction of a second. In business and industry, computers are used mainly for data processing, which includes tasks such as word processing, analysing data, entering records, payroll processing, personnel record keeping, and inventory management. Hospitals When computers are fed with mathematical equations along with data about air pressure, temperature, humidity, and other values, the solution of these equations gives an accurate prediction of the weather of a particular area. For example, a Cray X-MP supercomputer installed at Mausam Bhavan in New Delhi is used to predict weather and climatic changes in the Indian subcontinent. Education A computer is a powerful teaching aid and acts as another teacher in the classroom. Teachers use computers to develop instructional material. Teachers may use pictures, graphs, and graphical presentations to easily illustrate an otherwise difficult concept. Moreover, teachers at all levels can use computers to administer assignments and keep track of grades. Besides teachers, most students also prefer to learn from an e-learning software rather than from a book. Students can also give online exams and get instant results. O xf or d Un iv er Hospitals use computers to record every information about patients, from the time of their admission till their exit. For example, the date, time, reason for being admitted, the doctor being consulted, all prescribed medications, doctor visits, other hospital services, bills, etc., are all stored in computers. Moreover, computer-controlled devices are widely used to monitor pulse rate, blood pressure, and other vital signs of the patient, and in an emergency situation an alarm is used to notify nurses and other attendants. Moreover, computers are used as an aid to differently abled people. For example, computers are used to develop more effective artificial limbs for amputees. Dentists also use computers to diagnose jaw misalignments by placing a magnetic square containing three sensors between the front teeth and lip. The sensors are attached to a computer; they follow the magnet’s movement by tracing the line on the screen as the patient’s mouth opens. If the jaw moves improperly, the line will bend; else if the line is straight, the patient just needs to keep flossing. Weather Forecasting es s Business and Industry Pr Computers are used to prepare tickets, monitor the routes of trains and aeroplanes, and guide planes to a safe landing. They are also used to research about hotels in an area, reserve rooms, or to rent a car. sit y Travel and Tourism Simulation Supercomputers that can process enormous amount of data are widely used in simulation tests. Simulation of automobile crashes or aeroplane emergency landings is done to identify potential weaknesses in designs without risking human lives. Supercomputers also enable engineers to design aircraft models and simulate the effects that winds and other environmental forces will have on those designs. Even the astronauts at NASA are trained using computer-simulated problems that could be encountered during the launch, in space, or upon re-entry in to the earth’s atmosphere. Geology Civil engineers use computers to evaluate the effects of an earthquake on the structure of buildings based on age, Online Banking The world today is moving towards a cashless society, where you need not have money in your pocket to purchase anything. You can just have your credit card or debit card with you. The ATMs provide a 24 × 7 service and allow you to draw cash, check the balance in your account, and order a product. Industry and Engineering Computers are found in all kinds of industries, such as thermal power plants, oil refineries, and chemical industries, for process control, computer aided designing (CAD), and computer aided manufacturing (CAM). Computerized process control (with or without human intervention) is used to enhance efficiency in applications such as production of various chemical products, oil refining, paper manufacture, and rolling and cutting steel to customer requirements. In CAD, computers and graphics-oriented software are integrated for automating the design and drafting process. It helps an engineer to design a 3D machine part, analyse its © Oxford University Press. All rights reserved. Introduction to Computers view the trends in the market, and predict the future of their products. Managers also use decision support systems to analyse market research data, to size up the competition, and to plan effective strategies for penetrating their markets. characteristics, and then subject it to simulated stresses. In case a part fails the stress test, its specifications can be modified on the computer and retested. The final design specifications are released for production only when the engineer is satisfied that the part meets strength and other quality considerations. The CAM phase begins when the CAD phase is complete. In this phase, the metal or other materials are manufactured while complying with their specifications. For this computer controlled manufacturing, tools are used to produce highquality products. Expert Systems Robots Pr sit y iv er • First-generation computers used a very large instructions and performs computations based on those instructions. Today, computers are used in all interactive devices, such as cellular telephones, GPS units, portable organizers, ATMs, and gas pumps, among others. A computer accepts data, processes it, and produces information. Here, data is some raw facts or ﬁgures, and information is the processed data. The speed of the computer is usually given in nanoseconds and picoseconds. The term computer generation refers to the different advancements of new computer technology. With each new generation of computers, the circuitry became smaller and more advanced than that in its previous generation. number of vacuum tubes for circuitry and magnetic drums for memory. Second-generation computers were manufactured using transistors rather than vacuum tubes. • The development of the integrated circuit was the hallmark of the third-generation computers. The microprocessor started the fourth generation of computers, with thousands of integrated circuits built onto a single silicon chip. The ﬁfth-generation computers are completely based on the new concept of AI. • The CU is the central nervous system of the entire computer system. It manages and controls all the components of the computer system. • The CPU is a combination of the ALU and the CU. The CPU is better known as the brain of the computer system. Computer An electronic machine that takes instructions and performs computations based on those instructions. GUI A type of user interface that enables users to interact with programs in more ways than typing. A GUI offers graphical icons and visual indicators to display the information and actions available to a user. The actions are performed by direct manipulation of the graphical elements. Program A set of instructions executed by the computer. • • or d • • GLOSSARY Un • A computer is an electronic machine that takes O xf SUMMARY Computers help managers to analyse their organization’s data to understand the present scenario of their business, Expert systems are used to automate the decision-making process in a specific area, such as analysing the credit histories for loan approval and diagnosing a patient’s condition for prescribing an appropriate treatment. Expert systems analyse the available data in depth to recommend a course of action. A medical expert system might provide the most likely diagnosis of a patient’s condition. To create an expert system, an extensive amount of human expertise in a specific area is collected and stored in a database, also known as knowledge base. A software called an interface engine analyses the data available in the knowledge base and selects the most appropriate response. Adding more to it, in today’s scenario, computers are used to find jobs on the Internet, find a suitable match for a boy or girl, read news and articles online, find your batch mates, send and receive greetings pertaining to different occasions, etc. es s Robots are computer-controlled machines mainly used in the manufacturing process in extreme conditions where humans cannot work, for example, in high-temperature, high-pressure conditions or in processes that demand very high levels of accuracy. The main distinguishing feature between a robot and other automated machines is that a robot can be programmed to carry out a complex task and then reprogrammed to carry out other complex tasks. Decision Support Systems 11 © Oxford University Press. All rights reserved. es s Fill in the Blanks Vacuum tube A device sometimes used to amplify electronic signals. Semiconductor devices Electronic components that make use of the electronic properties of semiconductor materials (e.g., silicon, germanium). The conductivity of such devices can be controlled by introducing an electric ﬁeld, by exposure to light, and even pressure and heat, thereby making such devices excellent sensors. Transistor A semiconductor device that is used to amplify and switch electronic signals. Although some transistors are packaged individually, others are usually found embedded in ICs. Integrated circuit Also called a chip or microchip, an IC is a semiconductor wafer on which thousands or millions of tiny resistors, capacitors, and transistors are fabricated. It can be used as an ampliﬁer, oscillator, timer, counter, computer memory, or microprocessor. Garbage-in, garbage-out If input data is wrong, then the output will also be erroneous. Pr Expert systems Custom-written computer programs that are ‘expert’ in a particular problem area, and embody a human expert’s knowledge, experience, and problem-solving strategies. They are being used in many areas such as medicine, chemistry, geology, meteorology, computer systems, and so on. Neural networks Systems that simulate intelligence by reproducing the physical connections that takes place in animal brains. Robotics Computers programmed to look, listen, and react to other sensory stimuli. Stylus An electronic pen that looks like a small ballpoint pen. Internet A network of networks that connects computers all over the world. Storage The process of saving data and instructions permanently in the computer so that it can be used for processing. Input The process of entering data and instructions into the computer system. Memory shadow The process of copying data from CMOS into RAM. iv er sit y GLOSSARY Fundamentals of Computers EXERCISES or d Un 1. A program is the ________. 2. Computers operate on ________ based on ________. 3. Computers can perform ________ calculations in a second. 4. The speed of computers is expressed in ________ or ________. 5. Raw facts or ﬁgures are called ________. 6. ________ is an example of primary memory. 7. ________ and ________ are examples of ﬁrst-generation computing devices. 8. Second-generation computers were ﬁrst developed for the ________ industry. 9. ________ packages allow easy manipulation and analysis of data organized in rows and columns. 10. CRAY-1, CRAY-2, Control Data CYBER 205, and ETA A-10 are ________. 11. ________ enables the television to use a telephone line to communicate and connect to the Internet. O xf 12 Multiple Choice Questions 1. The ﬁrst commercial computer delivered to a business client is: (a) UNIVAC (b) ENIAC (c) EDSAC (d) None of these 2. The technology used in the manufacture of secondgeneration computers is: (a) Vacuum tubes (b) Transistors (c) ICs (d) None of these 3. The generation of computers in which time sharing operating systems were used is: (a) First (b) Second (c) Third (d) Fourth 4. The computer languages that are specially designed for the ﬁfth generation of computers are: (a) ALGOL (b) SNOBOL (c) LISP (d) Prolog 5. Web TV is an example of: (a) Supercomputer (b) Minicomputer (c) Network computer (d) Laptop 6. The brain of the computer is the: (a) Control unit (b) ALU (c) CPU (d) All of these State True or False 1. Computers work on the GIGO concept. 2. 1 nanosecond = 1 × 10−12 seconds. 3. Floppy disk and hard disk are examples of primary memory. 4. First-generation computers used a very large number of transistors. © Oxford University Press. All rights reserved. Review Questions or d Un iv er sit y Pr 1. Deﬁne a computer. 2. Differentiate between data and information. 3. Differentiate between primary memory and secondary memory. 4. Write a short note on the characteristics of a computer. 5. Computers work on the garbage-in, garbage-out concept. Comment. 6. Explain the evolution of computers. Also, state how computers in one generation are better than their predecessors. 7. Broadly classify computers based on their speed, the amount of data that they can hold, and price. 8. Discuss the variants of microcomputers that are widely used today. 9. Explain the areas in which computers are being applied to carry out routine and highly specialized tasks. es s 5. First-generation computers could be programmed only in binary language. 6. ALGOL is used in the third-generation computers. 7. Fifth-generation computers are based on AI. 8. Network computers have more processing power, memory, and storage than a desktop computer. 9. RAM stores the data and parts of program, the intermediate results of processing, and the recently generated results of jobs that are currently being worked on by the computer. 10. Operating systems such as MS-DOS, Windows, and UNIX were introduced during the fourth generation of computers. O xf EXERCISES Introduction to Computers © Oxford University Press. All rights reserved. 13 2 es s Input and Output Devices sit y Pr Learning Objectives INPUT DEVICES or 2.1 d Un iv er In order to accomplish tasks, a computer must be able to interact with its users. For this purpose, we need input and output devices, which are also known as peripheral devices. There are different types of input/output devices, and each device has capabilities that differentiate it from the others. In this chapter, we will read about some peripheral devices that are widely used these days. devices. Figure 2.1 categorizes input devices into different groups. O xf An input device is used to feed data and instructions into the computer. In the absence of an input device, a computer would have only been a display device. In this section, we will read about some of the widely used input 2.1.1 Keyboard The keyboard is the main input device for computers. Computer keyboards look very similar to the keyboards of Input devices Keyboard Pointing devices Handheld devices Optical devices Audio/Visual devices Mouse Pen Barcode readers Trackball Touchscreen Scanners Trackpad Joystick OCR OMR MICR Fig. 2.1 Categories of input devices © Oxford University Press. All rights reserved.