CIT 104 Introduction to Computers Course Guide PDF

COURSE GUIDE CIT 104 INTRODUCTION TO COMPUTERS Course Team Samuel O. Oluwadare Course Developer/Writer) - Federal University of Technology, Akure-Nigeria Professor A. Adebanjo (Programme Leader) – NOUN Dr. Jori Sanusi & Adams, A. E (Course Coordinators) – NOUN NATIONAL OPEN UNIVERSITY OF NIGERIA CIT 104 COURSE GUIDE National Open University of Nigeria Headquarters Airport Road, Jabi, Abuja e-mail: [email protected] URL: www.nou.edu.ng Published by National Open University of Nigeria Printed 2008 Reprinted 2014, 2020 ISBN: 978-058-258-4 All Rights Reserved ii CIT 104 COURSE GUIDE CONTENTS PAGE Introduction …………………………………………..…… iv Course Contents………………………………………..…. iv Course Aims……………………………………………..… iv Course Objectives……………………………………..…… v Working through the Course…………………………….… v Course Materials…………………………………………… v Study Units………………………………………………….. vi Textbooks and References……………………………….… vii Assessment …………………………….…………………… x Tutor-Marked Assignment…………………………………... x Final Examination and Grading……………………………... x Summary…………………………………………………..…. x iii CIT 104 COURSE GUIDE INTRODUCTION The computer is fast becoming the universal machine of the twenty-first century. Early computers were large in size and too expensive to be owned by individuals. Thus they were confined to the laboratories and few research institutes. They could only be programmed by computer engineers. The basic applications were confined to undertaking complex calculations in science and engineering. Today, the computer is no longer confined to the laboratory. Computers, and indeed, computing have become embedded in almost every item we use. Computing is fast becoming ubiquitous. Its application transcends science, engineering, communication, space science, aviation, financial institutions, social sciences, humanities, the military, transportation, manufacturing, the extractive industries to mention but a few. Also, early computers were designed to accept numeric data, but over the years computers have been developed to accept not only numeric data, but we also able to process multimedia data – text, audio and video. The combination of computer technology and communications technology gave birth to what is now widely known as Information and Communication Technologies (ICT). ICT has changed the face of virtually all fields of human endeavour, ranging from science to engineering, commerce and industry, international trade, transportation, culture and tourism, education and research, among others. Nowadays, literacy is not only measured by the ability to read and write, but also includes computer literacy. The wave of globlisation which has been largely propelled by the collapse of barriers of distance between nations and peoples in the world as a result of ICT, makes it imperative for the modern man to have at least the basic knowledge of computers. This course is meant to introduce students to the historical evolution of computers, the basic components of computers, and some of its applications in society. COURSE CONTENTS This Course Guide tells you what to expect from reading this material. The study of computers is not only of academic importance but is also a universal tool of the twenty-first century. This course, therefore, is a systematic approach to the understanding of computers and their applications. COURSE AIMS The aim of this course is to provide students with the basic understanding of the computer and its applications in everyday life. iv CIT 104 COURSE GUIDE COURSE OBJECTIVES The specific objectives of this course are to:  Provide basic understanding of the historical evolution of the computer, types of computers and the classification of computers.  Enable the students to understand the components of the computer – the hardware and software.  Help students to identify the different categories of computer software and their uses.  Introduce students to computer programming with emphasis on the building blocks and stages of programming and writing of computer programs using visual basic.  Enable students to identify and appreciate the areas of application of computers in society, thereby stimulating their thought to regard the computer as a tool for human use rather than a master.  Create awareness at the early stage of the study of computers about the potential threats that computer viruses pose to the smooth operations of computers. WORKING THROUGH THE COURSE This course requires that you spend a lot of time to read. The material though presented in simple language, coherent and in logical sequence, requires diligent study. The material is comprehensive and would require full commitment and dedication to study on the part of the student. You are, therefore, advised to avail yourself the opportunity of attending the tutorial sessions where you would have the opportunity of comparing knowledge with your peers. COURSE MATERIALS You will be provided with the following materials:  Course Guide  Modules  Study units  List of recommended textbooks which will serve as compliments to the course material v CIT 104 COURSE GUIDE STUDY UNITS The course is made up of seven modules organised into 19 study units as follows: Module 1 Understanding the Computer Unit 1 Basic Concepts Unit 2 Historical Overview of the Computer Unit 3 Classification of Computers Module 2 Computer Hardware Unit 1 Hardware Components (1) Unit 2 Hardware Components (2) – Peripheral Devices Unit 3 Auxiliary Equipment Module 3 Computer Software Unit 1 Computer Software (1) Unit 2 Computer Software (2) Module 4 Programming the Computer Unit 1 Computer Languages Unit 2 Basic Principles of Computer Programming Unit 3 Flowcharts and Algorithms Module 5 Computer Application Programming Unit 1 Programming in Visual Basic (1) Unit 2 Visual Basic Project Window Unit 3 Creating Menu Applications Unit 4 Analysing Visual Basic Data Module 6 Areas of Application of Computers Unit 1 Application of Computers in Education Unit 2 Application of Computers in Business and Industry Unit 3 Application of Computers in Government, Military, etc Module 7 Threats to the Computer Unit 1 Computer Virus vi CIT 104 COURSE GUIDE Synopses of the Study Units Module 1 Unit 1: This unit presents the definition of the computer, basic understanding of data processing, the concept of data and information, methods of data processing and the characteristics of a computer. Module 1 Unit 2: It gives the brief history of the computer technology, evolution of computer and the generations of computers. Module 1 Unit 3: You are introduced to the classification of computers. This involves classification based on size, type of signal and purpose. At the end of the unit you will be able to differentiate between one classes of computer from the others. Module 2 Unit 1: In this unit you will be familiarised with hardware components of the computer. This will enable you to appreciate the importance of each component to the overall smooth operation of the computer. Module 2 Unit 2: in this unit, you are introduced to the peripheral devices. Also, you will be able to get deeper understanding of the functions of the input and output units. The knowledge acquired in this unit will give you a guide on the type of input and output units suitable to a particular computing environment. Module 2 Unit 3: The unit discusses the computer auxiliary equipment such as the air conditioner, voltage stabiliser and the Uninterruptible Power Supply System (UPS). Module 3 Unit 1: This unit introduces the computer software in some detail. You will learn about the system software, language translators such as compliers and the utility software. Module 3 Unit 2: This unit builds on the knowledge acquired in the previous unit by discussing various types of language translators, utility programs and application programs in greater detail. Module 4 Unit 1: In this unit you will learn about computer programming languages such as low level language (machine language and assemblers) and the high level languages. Module 4 Unit 2: You will be introduced to computer programming in this unit. Topics covered include the concept of problem solving with computers, principles of programming and stages of programming. vii CIT 104 COURSE GUIDE Module 4 Unit 3: This unit advances further on unit 10 by discussing the use of flowcharts and algorithms in computer programming. These two concepts are essential ingredients to the writing of well structured computer programs. Module 5 Unit 1: This unit begins our discussions on programming the computer in Visual Basic. Units 12 through 15 are dedicated to this subject. The discussions are practical in nature. The materials presented in these four units are in the form of hands-on-practice. You will benefit more and, in fact, enjoy it better if you can try them using a personal computer. The steps involved are simple and explicit. By the time you run through the four units you should be able to write simple visual basic application programs. Specifically, unit 12 introduces the concept of working with graphical objects, general visual basic programming concepts, how to design a project from application wizard, and how to use the toolbox. Module 5 Unit 2: In this unit you will learn about the visual basic project window. This will enable you to gain more mastery of the visual basic programming environment. Module 5 Unit 3: In this unit you will learn how to create menu applications. The menu system is one of the high points of object oriented programming languages. It makes the application user-friendly and interactive. This unit, therefore, equips you with the principles and steps involved in creating visual basic applications with menu. Module 5 Unit 4: This unit concludes the discussions on programming computers in visual basic. Specifically, this unit takes you through the analysis of visual basic data. If you have truly followed all the principles and steps discussed in the three previous units you should at this stage be able to plan, design, code and implement a simple but complete visual basic application. Module 6 Unit 1: This unit begins the series of presentations on the areas of application of computers in society. The main aim is to identify some areas of application to society at large. It is also meant to enlighten you on the various job opportunities for computer literate persons in the society. Specifically, in this unit, you are presented with detailed discussion on the areas of application of computers in education. Module 6 Unit 2: This unit takes further the discussion on the areas of application of computers by presenting in greater detail its application in business and industry. It discusses the application of computer in the development and operations of payroll, inventory control, auditing operations, personnel record keeping, preparation of customer utility bills and payment orders, management information systems, high quality viii CIT 104 COURSE GUIDE production control, point of sale service, financial market and the publishing industry. Module 6 Unit 3: This unit concludes the discussions on the areas of application of computers with particular reference to its application in science and engineering, health care, transport and communications, recreation, government and the military. Module 7 Unit 1: This is the concluding unit of this course. It presents a discussion on computer virus as one of the major threats to the smooth operations of computers. Detailed discussions on computer virus, its mode of transmission, detection, prevention and cure, are presented. TEXTBOOKS AND REFERENCES More recent editions of these books are recommended for further reading: Akinyokun, O.C. (1999). Principles and Practice of Computing Technology. Ibadan: International Publishers Limited. Balogun, V.F., Daramola, O.A., Obe, O.O., Ojokoh, B.A., and Oluwadare S.A. (2006). Introduction to Computing: A Practical Approach. Akure: Tom-Ray Publications. Chuley, J.C. (1987). Introduction to Low Level Programming for Microprocessors. Macmillan Education Ltd. Francis Scheid (1983). Schaum’s Outline Series: Computers and Programming. Singapore: McGraw-Hill Book Company. Gray S. Popkin and Arthur H. Pike (1981). Introduction to Data Processing with BASIC,(2nded). Boston: Houghton Mifflin Company. Oliver E.C. and Chapman R.J. (1986). Data Processing (7th ed). ELBS/DP Publications. Richard H. Austin and Lillian Cassel (1986). Computers in Focus. Monterey, California: Books/Cole Publication Company. Tunji and Dokun (1993). Data Processing: Principles and Concepts. Lagos: Informatics Books. In addition to these books, you can browse on the Internet to get additional materials on the topics covered in this course. ix CIT 104 COURSE GUIDE ASSESSMENT There are two components of assessment for this course. The Tutor - Marked Assignment (TMA), and the end of course examination. TUTOR-MARKED ASSIGNMENT The TMA is the continuous assessment component of your course. It accounts for 30% of the total score. You will be given six (6) TMAs to answer. They must be answered before you are allowed to sit for the end of course examination. The TMAs would be given to you by your facilitators at the appropriate time during the course. FINAL EXAMINATION AND GRADING This examination concludes the assessment for the course. It constitutes 70% of the whole course. You will be informed of the time for the examination. It may or may not coincide with the university semester examination. SUMMARY This course intends to introduce you to the basic understanding of the computer and its application in various areas of human endeavour. By the time you complete studying this course, you should be able to answer basic questions such as:  What is the computer?  What are the evolutionary trends in the development of the computer?  What are the different components of computers?  What are the different categories of computer software?  What are the areas of application of computers in society?  How could you use the computer to create user-friendly, menu- driven and interactive applications?  What are the threats to the smooth operation of the computer?  How can you detect, prevent and cure computer viruses? We wish you success in this course. We do hope that this course will give you a good head start in the understanding and use of computers. Best wishes as you enjoy the course. x MAIN COURSE CONTENTS PAGE Module 1 Understanding the Computer …………………… 1 Unit 1 Basic Concepts……………………………….…..… 1 Unit 2 A Historical Overview of the Computer…………… 9 Unit 3 Classification of Computers…………………….….. 20 Module 2 Computer Hardware ……………………………. 27 Unit 1 Hardware Components (1)………………………... 27 Unit 2 Hardware Components (2) – Peripheral Devices…. 40 Unit 3 Auxiliary Equipment…………………………....…. 53 Module 3 Computer Software …………………………..…. 57 Unit 1 Computer Software (1)………………………….… 57 Unit 2 Computer Software (2)…………………………..… 69 Module 4 Programming the Computer ……………………. 75 Unit 1 Computer Languages…………………………….... 75 Unit 2 Basic Principles of Computer Programming……..... 84 Unit 3 Flowcharts and Algorithms……………………….… 91 Module 5 Computer Application Programming Using Visual Basic ………………………………………. 102 Unit 1 Programming in Visual Basic (1)……………...…. 102 Unit 2 Visual Basic Project Window……………………. 109 Unit 3 Creating Menu Applications……………………... 117 Unit 4 Analysing Visual Basic Data…………………..…. 126 Module 6 Areas of Application of Computers …………..…. 134 Unit 1 Application of Computers in Education………..…. 134 Unit 2 Computer Applications in Business and Industry…………………………………………….. 137 Unit 3 Computer Applications in Government, Science, Engineering, Transport, Communications, Recreation and the Military…………………………. 145 Module 7 Threats to the Computer ………………………...… 153 Unit 1 Computer Virus…………………………………..… 153 CIT 104 MODULE 1 MODULE 1 UNDERSTANDING THE COMPUTER Unit 1 Basic Concepts Unit 2 Historical Overview of the Computer Unit 3 Classification of Computers UNIT 1 BASIC CONCEPTS CONTENTS 1.0 Introduction 2.0 Objectives 3.0 Main Content 3.1 Definitions 3.2 Methods of Data Processing 3.3 Characteristics of a Computer 3.4 The Computer System 4.0 Conclusion 5.0 Summary 6.0 Tutor-Marked Assignment 7.0 References/Further Reading 1.0 INTRODUCTION The computer is fast becoming the universal machine of the 21st century. Early computers were large in size and too expensive to be owned by individuals. Thus they were confined to the laboratories and few research institutes. They could only be programmed by computer engineers. The basic applications were confined to undertaking complex calculations in science and engineering. Today, the computer is no longer confined to the laboratory. Computers and, indeed, computing have become embedded in almost every item we use. Computing is fast becoming ubiquitous. Its application transcends science, engineering, communication, space science, aviation, financial institutions, social sciences, humanities, the military, transportation, manufacturing, and extractive industries to mention but a few. This unit presents the background information about computers. 1 CIT 104 INTRODUCTION TO COMPUTERS 2.0 OBJECTIVES At the end of this unit you should be able to:  define the computer  explain data processing  explain data and information  identify methods of data processing  mention the characteristics of a computer. 3.0 MAIN CONTENT 3.1 Definitions Computer: A computer is basically defined as a tool or machine used for processing data to give required information. It is capable of:  taking input data through the keyboard (input unit),  storing the input data in a diskette, hard disk or other medium,  processing it in the central processing unit (CPU) and  giving out the result (output) on the screen or the Visual Display Unit (VDU). INPUT PROCESSING OUTPUT (DATA) (INFORMATION) Fig. 1: A schematic diagram to define a computer Data: The term data refers to facts about a person, object or place, e.g. name, age, complexion, school, class, height etc. Information: This is referred to as processed data or a meaningful statement, e.g. net pay of workers, examination results of students, list of successful candidates in an examination or interview etc. 3.2 Methods of Data Processing The following are the three major methods that have been widely used for data processing over the years:  The Manual method, 2 CIT 104 MODULE 1  The Mechanical method and  The Computer method. The Manual Method The manual method of data processing involves the use of chalk, wall, pen, pencil and the like. These devices, machines or tools facilitate human efforts in recording, classifying, manipulating, sorting and presenting data or information. The manual data processing operations entail considerable manual efforts. Thus, the manual method is cumbersome, tiresome, boring, frustrating and time consuming. Furthermore, the processing of data by the manual method is likely to be affected by human errors. When there are errors, then the reliability, accuracy, neatness, tidiness, and validity of the data would be in doubt. The manual method does not allow for the processing of large volumes of data on a regular and timely basis. The Mechanical Method The mechanical method of data processing involves the use of machines such as the typewriter, roneo machines, adding machines and the like. These machines facilitate human efforts in recording, classifying, manipulating, sorting and presenting data or information. The mechanical operations are basically routine in nature. There is virtually no creative thinking. Mechanical operations are noisy, hazardous, error prone and untidy. The mechanical method does not allow for the processing of large volumes of data continuously and timely. The Computer Method The computer method of carrying out data processing has the following major features:  Data can be steadily and continuously processed  The operations are practically not noisy  There is a store where data and instructions can be stored temporarily and permanent.  Errors can be easily and neatly corrected.  Output reports are usually very neat, decent and can be produced in various forms such as adding graphs, diagrams and pictures etc.  Accuracy and reliability are highly enhanced  Below are further attributes of a computer which make an indispensable tool for humans. 3 CIT 104 INTRODUCTION TO COMPUTERS 3.3 Characteristics of a Computer  Speed: The computer can manipulate large data at incredible speed and response time can be very fast.  Accuracy: Its accuracy is very high and its consistency can be relied upon. Errors committed in computing are mostly due to human rather than technological weakness. There are in-built error detecting schemes in the computer.  Storage: It has both internal and external storage facilities for holding data and instructions. This capacity varies from one machine to the other. Memories are built up in K (Kilo) modules where K=1024 memory locations.  Automatic: Once a program is in the computer’s memory, it can run automatically each time it is opened. The individual has little or no instruction to give again.  Reliability: Being a machine, a computer does not suffer human traits of tiredness and lack of concentration. It will perform the last job with the same speed and accuracy as the first job every time even if ten million jobs are involved.  Flexibility: It can perform any type of task once it can be reduced to logical steps. Modern computers can be used to perform a variety of functions like on-line processing, multi- programming, real time processing etc. 3.4 The Computing System The computing system is made up of the computer system, the user and the environment in which the computer is operated. The Computer System The computer system is made up of the hardware and the software. The Hardware The computer hardware comprises the input unit, the processing unit and the output unit. The input unit comprises those media through which data is fed into the computer. Examples include the keyboard, mouse, joystick, trackball and scanner. The processing unit is made up of the Arithmetic and Logic Unit (ALU), the control unit and the main memory. The main memory also known as the primary memory is made up of the Read Only Memory (ROM) and the Random Access Memory (RAM). 4 CIT 104 MODULE 1 The output unit is made up of those media through which data, instructions for processing the data (program), and the result of the processing operation are displayed for the user to see. Examples of the output unit are the monitor (Visual Display Unit) and the printer. Software Computer software is the series of instructions that enable the computer to perform a task or group of tasks. A program is made up of a group of instructions to perform a task. Series of programs linked together make up software. Computer programs could be categorised into system software, utility software, and application programs. Computer Users Computer users are the different categories of personnel that operate the computer. We have expert users and casual users. The expert users could be further categorised into computer engineers, computer programmers and computer operators. The Computing Environment The computing environment includes the building housing the other elements of the computing system namely the computer and the users, the furniture, auxiliary devices such as the voltage stabiliser, the Uninterruptible Power Supply System (UPS), the fans, the air conditioners etc. The schematic diagram of the computing system is presented in Fig. 2a. to Fig. 2d. The computing system Hardware Software Users The computing environment Fig 2a: A Schematic diagram of the computing system 5 CIT 104 INTRODUCTION TO COMPUTERS Software System software Utility software Application software Operating Anti Scandisk Word Spread Statistical system virus processo sheet packages r Fig. 2b: Computer software Computer users Expert users End users Casual users System Programme Computer Data entry engineers rs operators clerks Fig. 2c: Computer users 6 CIT 104 MODULE 1 Computing environment Building Furniture Auxiliary devices and fittings Air Voltage UPS conditione stabilizer r Fig. 2d: Computing environment 4.0 CONCLUSION The computer is a machine used for a variety of purposes. Its use transcends all areas of human endeavours owing to the advantages of the computer method of data processing over the manual and mechanical methods of data processing. 5.0 SUMMARY This unit has taught the following:  The computer is any electronic device that can accept data, process it and produce an output  The computer method of data processing is superior to the manual and mechanical methods of data processing  The computing system is made up of the computer system, the users and the computing environment. 7 CIT 104 INTRODUCTION TO COMPUTERS 6.0 TUTOR-MARKED ASSIGNMENT 1 a. What is a computer? b. What are the advantages of the computer method of data processing over the manual and mechanical methods of data processing. 2. Draw a schematic diagram of a computing system and describe each of the components. 7.0 REFERENCES/FURTHER READING Akinyokun, O.C. (1999). Principles and Practice of Computing Technology. Ibadan: International Publishers Limited. Balogun,V.F., Daramola, O.A.. Obe, O.O. Ojokoh, B.A., and Oluwadare S.A. (2006). Introduction to Computing: A Practical Approach. Akure: Tom- Ray Publications. 8 CIT 104 MODULE 1 UNIT 2 A HISTORICAL OVERVIEW OF THE COMPUTER CONTENTS 1.0 Introduction 2.0 Objectives 3.0 Main Content 3.1 A Brief History of Computer Technology 3.2 First Generation Electronic Computers (1937-1953) 3.3 Second Generation (1954-1972) 3.4 Third Generation (1903-1972) 3.5 Fourth Generation (1972-1984) 3.6 Fifth Generation (1984-1990) 3.7 Sixth Generation (1990-Date) 4.0 Conclusion 5.0 Summary 6.0 Tutor-Marked Assignment 7.0 References/Further Reading 1.0 INTRODUCTION The computer as we know it today has evolved over the ages. An attempt is made in this unit to present in chronological order the various landmarks and milestones in the development of the computer. Based on the milestone achievement of each era, the computer evolution is categorised into generations. The generational classification, however, is not rigid as we may find one generation eating into the next. 2.0 OBJECTIVES At the end of this unit you should be able to:  explain the processes leading to the emergence of the modern computer  predict the direction of research in computer technology in the near future. 3.0 MAIN CONTENT 3.1 A Brief History of Computer Technology A complete history of computing would include a multitude of diverse devices such as the ancient Chinese abacus, the Jacquard loom (1805) and Charles Babbage’s “analytical engine” (1834). It would also 9 CIT 104 INTRODUCTION TO COMPUTERS include a discussion of mechanical, analog and digital computing architectures. As late as the 1960s, mechanical devices, such as the Marchant calculator, still found widespread application in science and engineering. During the early days of electronic computing devices, there was much discussion about the relative merits of analog vs. digital computers. In fact, as late as the 1960s, analog computers were routinely used to solve systems of finite difference equations arising in oil reservoir modeling. In the end, digital computing devices proved to have the power, economics and scalability necessary to deal with large scale computations. Digital computers now dominate the computing world in all areas ranging from the hand calculator to the supercomputer and are pervasive throughout society. Therefore, this brief sketch of the development of scientific computing is limited to the area of digital, electronic computers. The evolution of digital computing is often divided into generations. Each generation is characterised by dramatic improvements over the previous generation in the technology used to build computers, the internal organisation of computer systems, and programming languages. Although not usually associated with computer generations, there has been a steady improvement in algorithms, including algorithms used in computational science. The following history has been organised using these widely recognized generations as mileposts. 3.2 First Generation Electronic Computers (1937 – 1953) Three machines have been promoted at various times as the first electronic computers. These machines used electronic switches, in the form of vacuum tubes, instead of electromechanical relays. In principle the electronic switches were more reliable, since they would have no moving parts that would wear out, but technology was still new at that time and the tubes were comparable to relays in reliability. Electronic components had one major benefit, however: they could “open” and “close” about 1,000 times faster than mechanical switches. The earliest attempt to build an electronic computer was by J. V. Atanasoff, a professor of physics and mathematics at Iowa State, in 1937. Atanasoff set out to build a machine that would help his graduate students solve systems of partial differential equations. By 1941, he and graduate student Clifford Berry had succeeded in building a machine that could solve 29 simultaneous equations with 29 unknowns. However, the machine was not programmable, and was more of an electronic calculator. A second early electronic machine was Colossus, designed by Alan Turning for the British military in 1943. This machine played an 10 CIT 104 MODULE 1 important role in breaking codes used by the German army in World War II. Turning’s main contribution to the field of computer science was the idea of the Turning Machine, a mathematical formalism widely used in the study of computable functions. The existence of Colossus was kept secret until long after the war ended, and the credit due to Turning and his colleagues for designing one of the first working electronic computers was slow in coming. The first general purposes programmable electronic computer was the Electronic Numerical Integrator and Computer (ENIAC), built by J. Presper Eckert and John V. Mauchly at the University of Pennysylvania. Work began in 1943, funded by the Army Ordinance Department, which needed a way to compute ballistics during World War II. The machine wasn’t completed until 1945, but then it was used extensively for calculations during the design of the hydrogen bomb. By the time it was decommissioned in 1955 it had been used for research on the design of wind tunnels, random number generators, and weather prediction. Eckert, Mauchly, and John Von Neumann, a consultant to the ENIAC project, began work on a new machine before ENIAC was finished. The main contribution of EDVAC, their new project, was the notion of a stored program. There is some controversy over who deserves the credit for this idea, but no one knows how important the idea was to the future of general purpose computers. ENIAC was controlled by a set of external switches and dials; to change the program required physically altering the settings on these controls. These controls also limited the speed of the internal electronic operations. Through the use of a memory that was large enough to hold both instructions and data, and using the program stored in memory to control the order of arithmetic operations, EDVAC was able to run orders of magnitude faster than ENIAC. By storing instructions in the same medium as data, designers could concentrate on improving the internal structure of the machine without worrying about matching it to the speed of an external control. Regardless of who deserves the credit for the stored program idea, the EDVAC project is significant as an example of the power of interdisciplinary projects that characterise modern computational science. By recognising that functions, in the form of a sequence of instructions for a computer, can be encoded as numbers, the EDVAC group knew the instructions could be stored in the computer’s memory along with numerical data. The notion of using numbers to represent functions was a key step used by Goedel in his incompleteness theorem in 1937, work which Von Neumann, as a logician, was quite familiar with. Von Neumann’s background in logic, combined with Eckert and 11 CIT 104 INTRODUCTION TO COMPUTERS Mauchly’s electrical engineering skills, formed a very powerful interdisciplinary team. Software technology during this period was very primitive. The first programs were written out in machine code, i.e. programmers directly wrote down the numbers that corresponded to the instructions they wanted to store in memory. By the 1950s programmers were using a symbolic notation, known as assembly language, then hand-translating the symbolic notation into machine code. Later programs known as assemblers performed the translation task. As primitive as they were, these first electronic machines were quite useful in applied science and engineering. Atanasoff estimated that it would take eight hours to solve a set of equations with eight unknowns using a Marchant calculator, and 381 hours to solve 29 equations for 29 unknowns. The Atanasoff-Berry computer was able to complete the task in under an hour. The first problem run on the ENIAC, a numerical simulation used in the design of the hydrogen bomb, required 20 seconds, as opposed to forty hours using mechanical calculators. Eckert and Mauchly later developed what was arguably the first commercially successful computer, the UNIVAC; in 1952, 45 minutes after the polls closed and with 7% of the vote counted, UNIVAC predicted Eisenhower would defeat Stevenson with 438 electoral votes (he ended up with 442). 3.3 Second Generation (1954 – 1962) The second generation saw several important developments at all levels of computer system design, from the technology used to build the basic circuits to the programming languages used to write scientific applications. Electronic switches in this era were based on discrete diode and transistor technology with a switching time of approximately 0.3 microseconds. The first machines to be built with this technology include TRADIC at Bell Laboratories in 1954 and TX-0 at MIT’s Lincoln Laboratory. Memory technology was based on magnetic cores which could be accessed in random order, as opposed to mercury delay lines, in which data was stored as an acoustic wave that passed sequentially through the medium and could be accessed only when the data moved by the I/O interface. Important innovations in computer architecture included index registers for controlling loops and floating point units for calculations based on real numbers. Prior to this accessing successive elements in an array was quite tedious and often involved writing self-modifying codes (programs which modified themselves as they ran; at the time viewed as 12 CIT 104 MODULE 1 a powerful application of the principle that programs and data were fundamentally the same, this practice is now frowned upon as extremely hard to debug and is impossible in most high level languages). Floating point operations were performed by libraries of software routines in early computers, but were done in hardware in second generation machines. During this second generation many high level programming languages were introduced, including FORTRAN (1956), ALGOL (1958), and COBOL (1959). Important commercial machines of this era include the IBM 704 and 7094. The latter introduced I/O processors for better throughput between I/O devices and main memory. The second generation also saw the first two supercomputers designed specifically for numeric processing in scientific applications. The term “supercomputer” is generally reserved for a machine that is an order of magnitude more powerful than other machines of its era. Two machines of the 1950s deserve this title. The Livermore Atomic Research Computer (LARC) and the IBM 7030 (aka Stretch) were early examples of machines that overlapped memory operations with processor operations and had primitive forms of parallel processing. 3.4 Third Generation (1963 – 1972) The third generation brought huge gains in computational power. Innovations in this era include the use of integrated circuits, or ICs (semiconductor devices with several transistors built into one physical component), semiconductor memories starting to be used instead of magnetic cores, microprogramming as a technique for efficiently designing complex processors, the coming of age of pipelining and other forms of parallel processing, and the introduction of operating systems and time-sharing. The first ICs were based on small-scale integration (SSI) circuits, which had around 10 devices per circuit (or “chip”), and evolved to the use of medium-scale integrated (MSI) circuits, which had up to 100 devices per chip. Multilayered printed circuits were developed and core memory was replaced by faster, solid state memories. Computer designers began to take advantage of parallelism by using multiple functional units, overlapping CPU and I/O operations, and pipelining (internal parallelism) in both the instruction stream and the data stream. In 1964, Seymour Cray developed the CDC 6600, which was the first architecture to use functional parallelism. By using 10 separate functional units that could operate simultaneously and 32 independent memory banks, the CDC 6600 was able to attain a computation rate of 1 million floating point operations per second (1 Mflops). Five years later 13 CIT 104 INTRODUCTION TO COMPUTERS CDC released the 7600, also developed by Seymour Cray. The CDC 7600, with its pipelined functional units, is considered to be the first vector processor and was capable of executing at 10 Mflops. The IBM 360/91, released during the same period, was roughly twice as fast as the CDC 6600. It employed instruction look ahead, separate floating point and integer functional units and pipelined instruction stream. The IBM 360-195 was comparable to the CDC 7600, deriving much of its performance from a very fast cache memory. The SOLOMON computer, developed by Westinghouse Corporation, and the ILLIAC IV, jointly developed by Burroughs, the Department of Defence and the University of Illinois, was representative of the first parallel computers. The Texas Instrument Advanced Scientific Computer (TI-ASC) and the STAR-100 of CDC were pipelined vector processors that demonstrated the viability of that design and set the standards for subsequent vector processors. Early in this third generation, Cambridge and the University of London cooperated in the development of CPL (Combined Programming Language, 1963). CPL was, according to its authors, an attempt to capture only the important features of the complicated and sophisticated ALGOL. However, the ALGOL CPL was large with many features that were hard to learn. In an attempt at further simplification, Martin Richards of Cambridge developed a subset of CPL called BCPL (Basic Computer Programming Language, 1967). 3.5 Fourth Generation (1972 – 1984) The next generation of computer systems saw the use of large scale integration (LSI –1000 devices per chip) and very large scale integration (VLSI –100,000 devices per chip) in the construction of computing elements. At this scale entire processors will fit onto a single chip, and for simple systems the entire computer (processor, main memory, and I/O controllers) can fit on one chip. Gate delays dropped to about Ins per gate. Semiconductor memories replaced core memories as the main memory in most systems; until this time the use of semiconductor memory in most systems was limited to registers and cache. During this period, high speed vector processors, such as the CRAY 1, CRAY X-MP and CYBER 205 dominated the high performance computing scene. Computers with large main memory, such as the CRAY 2, began to emerge. A variety of parallel architectures began to appear; however, during this period the parallel computing efforts were of a mostly experimental nature and most computational science was carried out on vector processors. Microcomputers and workstations were introduced and saw wide use as alternatives to time-shared mainframe computers. 14 CIT 104 MODULE 1 Developments in software include very high level languages such as FP (functional programming) and Prolog (programming in logic). These languages tend to use a declarative programming style as opposed to the imperative style of Pascal, C. FORTRAN, et al. In a declarative style, a programmer gives a mathematical specification of what should be computed, leaving many details of how it should be computed to the compiler and/or runtime system. These languages are not yet in wide use, but are very promising as notations for programs that will run on massively parallel computers (systems with over 1,000 processors). Compilers for established languages started to use sophisticated optimisation techniques to improve codes, and compilers for vector processors were able to vectorise simple loops (turn loops into single instructions that would initiate an operation over an entire vector). Two important events marked the early part of the third generation: the development of the C programming language and the UNIX operating system, both at Bell Labs. In 1972, Dennis Ritchie, seeking to meet the design goals of CPL and generalise Thompson’s B, developed the C language. Thompson and Ritchie then used C to write a version of UNIX for the DEC PDP-11. This C-based UNIX was soon ported to many different computers, relieving users from having to learn a new operating system each time they change computer hardware. UNIX or a derivative of UNIX is now a de facto standard on virtually every computer system. An important event in the development of computational science was the publication of the Lax report. In 1982, the US Department of Defence (DOD) and National Science Foundation (NSF) sponsored a panel on Large Scale Computing in Science and Engineering, chaired by Peter D. Lax. The Lax Report stated that aggressive and focused foreign initiatives in high performance computing, especially in Japan, were in sharp contrast to the absence of coordinated national attention in the United States. The report noted that university researchers had inadequate access to high performance computers. One of the first and most visible of the responses to the Lax report was the establishment of the NSF supercomputing centres. Phase I on this NSF program was designed to encourage the use of high performance computing at American universities by making cycles and training on three (and later six) existing supercomputers immediately available. Following this Phase I stage, in 1984 – 1985 the NSF provided funding for the establishment of five Phase II supercomputing centres. The Phase II centres, located in San Diego (San Diego Supercomputing Centre); Illinois (National Centre for Supercomputing Applications); Pittsburgh (Pittsburgh Supercomputing Center); Cornell (Cornell Theory 15 CIT 104 INTRODUCTION TO COMPUTERS Centre); and Princeton (John Von Neumann Centre), have been extremely successful at providing computing time on supercomputers to the academic community. In addition they have provided many valuable training programmes and have developed several software packages that are available free of charge. These Phase II centres continue to augment the substantial high performance computing efforts at the National Laboratories, especially the Department of Energy (DOE) and NASA sites. 3.6 Fifth Generation (1984 – 1990) The development of the next generation of computer systems is characterised mainly by the acceptance of parallel processing. Until this time, parallelism was limited to pipelining and vector processing, or at most to a few processors sharing jobs. The fifth generation saw the introduction of machines with hundreds of processors that could all be working on different parts of a single program. The scale of integration in semiconductors continued at an incredible pace, so that by 1990 it was possible to build chips with a million components – and semiconductor memories became standard on all computers. Other new developments were the widespread use of computer networks and the increasing use of single-user workstations. Prior to 1985, large scale parallel processing was viewed as a research goal, but two systems introduced around this time are typical of the first commercial products to be based on parallel processing. The Sequent Balance 8000 connected up to 20 processors to a single shared memory module (but each processor had its own local cache). The machine was designed to compete with the DEC VAX-780 as a general purpose Unix system, with each processor working on a different user’s job. However, Sequent provided a library of subroutines that would allow programmers to write programs that would use more than one processor, and the machine was widely used to explore parallel algorithms and programming techniques. The Intel iPSC-1, nicknamed “the hypercube”, took a different approach. Instead of using one memory module, Intel connected each processor to its own memory and used a network interface to connect processors. This distributed memory architecture meant memory was no longer a bottleneck and large systems (using more processors) could be built. The largest iPSC-1 had 128 processors. Toward the end of this period, a third type of parallel processor was introduced to the market. In this style of machine, known as a data-parallel or SIMD, there are several thousand very simple processors. All processors work under the direction of a single control unit; i.e. if the control unit says “add a to b” then all processors find their local copy of a and add it to their local 16 CIT 104 MODULE 1 copy of b. Machines in this class include the Connection Machine from Thinking Machines, Inc., and the MP-1 from MasPar, Inc. Scientific computing in this period was still dominated by vector processing. Most manufacturers of vector processors introduced parallel models, but there were very few (two to eight) processors in these parallel machines. In the area of computer networking, both wide area network (WAN) and local area network (LAN) technology developed at a rapid pace, stimulating a transition from the traditional mainframe computing environment towards a distributed computing environment in which each user has their own workstation for relatively simple tasks (editing and compiling programs, reading mail) but sharing large, expensive resources such as file servers and supercomputers. RISC technology (a style of internal organisation of the CPU) and plummeting costs for RAM brought tremendous gains in computational power of relatively low cost workstations and servers. This period also saw a marked increase in both the quality and quantity of scientific visualisation. 3.7 Sixth Generation (1990 to date) Transitions between generations in computer technology are hard to define, especially as they are taking place. Some changes, such as the switch from vacuum tubes to transistors, are immediately apparent as fundamental changes, but others are clear only in retrospect. Many of the developments in computer systems since 1990 reflect gradual improvements over established systems, and thus it is hard to claim they represent a transition to a new “generation”, but other developments will prove to be significant changes. In this section, we offer some assessments about recent developments and current trends that we think will have a significant impact on computational science. This generation is beginning with many gains in parallel computing, both in the hardware area and in improved understanding of how to develop algorithms to exploit diverse, massively parallel architectures. Parallel systems now compete with vector processors in terms of total computing power and, most especially, parallel systems to dominate the future. Combinations of parallel/vector architectures are well established, and one corporation (Fujitsu) has announced plans to build a system with over 200 of its high and vector processors. Manufacturers have set themselves the goal of achieving teraflops (1012 arithmetic operations per second) performance by the middle of the decade, and it is clear this 17 CIT 104 INTRODUCTION TO COMPUTERS will be obtained only by a system with a thousand processors or more. Workstation technology has continued to improve, with processor designs now using a combination of RISC, pipelining, and parallel processing. As a result it is now possible to procure a desktop workstation that has the same overall computing power (100 megaflops) as fourth generation supercomputers. This development has sparked an interest in heterogeneous computing: a program started on one workstation can find idle workstations elsewhere in the local network to run parallel subtasks. One of the most dramatic changes in the sixth generation is the explosive growth of wide area networking. Network bandwidth has expanded tremendously in the last few years and will continue to improve for the next several years. T1 transmission rates are now standard for regional networks, and the national “backbone” that interconnects regional networks uses T3. Networking technology is becoming more widespread than its original strong base in universities and government laboratories as it is rapidly finding application in K-12 education, community networks and private industry. A little over a decade after the warning voiced in the Lax report, the future of a strong computational science infrastructure is bright. 4.0 CONCLUSION The development of the computer spans through many generations with each generation chronicling the landmark achievements of the period. 5.0 SUMMARY This unit teaches that the development of the computer has spanned through six generations. 6.0 TUTOR-MARKED ASSIGNMENT 1. Outline the major landmarks of the fourth and fifth generations of computers. 2. Explain what is meant by stored program computer architecture. 18 CIT 104 MODULE 1 7.0 REFERENCES/FURTHER READING Akinyokun,O.C.(1999).Principles and Practice of Computing Technology. Ibadan: International Publishers Limited. Balogun, V.F., Daramola, O.A., Obe, O.O., Ojokoh, B.A. and Oluwadare S.A., (2006). Introduction to Computing: A Practical Approach. Akure: Tom-Ray Publications. Larry Long (1984). Introduction to Computers and Information Processing. New Jersey: Prentice-Hall Inc. Tunji and Dokun (1993). Data Processing, Principles and Concepts. Lagos: Informatics Books. 19 CIT 104 INTRODUCTION TO COMPUTERS UNIT 3 CLASSIFICATION OF COMPUTERS CONTENTS 1.0 Introduction 2.0 Objectives 3.0 Main Content 3.1 Categories of Computers 3.2 Classification Based on Signal Type 3.3 Classification by Purpose 3.4 Classification by Capacity 4.0 Conclusion 5.0 Summary 6.0 Tutor-Marked Assignment 7.0 References/Further Reading 1.0 INTRODUCTION The computer has passed through many stages of evolution from the days of the mainframe computers to the era of microcomputers. Computers have been classified based on different criteria. In this unit, we shall classify computers based on three popular methods. 2.0 OBJECTIVES At the end of this unit you should be able to:  classify computers based on size, type of signal and purpose  identify the features that differentiate one class of computers from the others. 3.0 MAIN CONTENT 3.1 Categories of Computers Although there are no industry standards, computers are generally classified in the following ways: 3.2 Classification Based on Signal Type There are basically three types of electronic computers. These are the Digital, Analog and Hybrid computers. 20 CIT 104 MODULE 1 The Digital Computer This represents its variables in the form of digits. The data it deals with, whether representing numbers, letters or other symbols, are converted into binary form on input to the computer. The data undergoes a processing after which the binary digits are converted back to alpha numeric form for output for human use. Because of the fact that business applications like inventory control, invoicing and payroll deal with discrete values (separate, disunited, discontinuous), they are best processed with digital computers. As a result of this, digital computers are mostly used in commercial and business places today. The Analog Computer It measures rather than counts. This type of computer sets up a model of a system. The common type represents its variables in terms of electrical voltage and sets up circuit analog to the equation connecting the variables. The answer can be either by using a voltmeter to read the value of the variable required, or by feeding the voltage into a plotting device. Analog computers hold data in the form of physical variables rather than numerical quantities. In theory, analog computers give an exact answer because the answer has not been approximated to the nearest digit. Whereas, when we try to obtain the answers using a digital voltmeter, we often find that the accuracy is less than that which could have been obtained from an analog computer. It is almost never used in business systems. It is used by scientists and engineers to solve systems of partial differential equations. It is also used in controlling and monitoring of systems in such areas as hydrodynamics and rocketry in production. There are two useful properties of this computer once it is programmed:  It is simple to change the value of a constant or coefficient and study the effect of such changes.  It is possible to link certain variables to a time pulse to study changes with time as a variable, and chart the result on an X-Y plotter. The Hybrid Computer In some cases, the computer user may wish to obtain the output from an analog computer as processed by a digital computer or vice versa. To achieve this, he set up a hybrid machine where the two are connected and the analog computer may be regarded as a peripheral of the digital computer. In such a situation, a hybrid system attempts to gain the advantage of both the digital and the analog elements in the same 21 CIT 104 INTRODUCTION TO COMPUTERS machine. This kind of machine is usually a special-purpose device which is built for a specific task. It needs a conversion element which accepts analog inputs, and outputs digital values. Such converters are called digitisers. There is a need for a converter from analog to digital also. It has the advantage of giving real-time response on a continuous basis. Complex calculations can be dealt with by the digital elements, thereby requiring a large memory, and giving accurate results after programming. They are mainly used in aerospace and process control applications. 3.3 Classification by Purpose Depending on their flexibility in operation, computers are classified as either special purpose or general purpose. Special-Purpose Computers A special purpose computer is one that is designed to solve a restricted class of problems. Such computers may even be designed and built to handle only one job. In such machines, the steps or operations that the computer follows may be built into the hardware. Most of the computers used for military purposes fall into this class. Other examples of special purpose computers include:  Computers designed specifically to solve navigational problems.  Computers designed for tracking airplanes or missiles  Computers used for process control applications in industries such as oil refinery, chemical manufacture, steel processing and power generation  Computers used as robots in factories like vehicle assembly plants and glass industries. General Attributes of Special-Purpose Computers Special-purpose computers are usually very efficient for the tasks for which they are specially designed. They are very much less complex than the general-purpose computers. The simplicity of the circuiting stems from the fact that provision is made only for limited facilities. They are very much cheaper than the general-purpose type since they involve fewer components and are less complex. 22 CIT 104 MODULE 1 General-Purpose Computers General-purpose computers are computers designed to handle a wide range of problems. Theoretically, a general-purpose computer can be adequate by means of some easily alterable instructions to handle any problems that can be solved by computation. In practice, however, there are limitations imposed by memory size, speed and the type of input/output devices. Examples of areas where general purpose computers are employed include the following:  Payroll  Banking  Billing  Sales analysis  Cost accounting  Manufacturing scheduling  Inventory control General Attributes of General-Purpose Computers  General-purpose computers are more flexible than special purpose computers. Thus, the former can handle a wide spectrum of problems.  They are less efficient than the special-purpose computers due to such problems as the following: - They have inadequate storage - They have low operating speed - Coordination of the various tasks and subsections may take time - General-purpose computers are more complex than special purpose computers. 3.4 Classification of Computers According to Capacity In the past, the capacity of computers was measured in terms of physical size. Today, however, physical size is not a good measure of capacity because modern technology has made it possible to achieve compactness. A better measure of capacity today is the volume of work that a computer can handle. The volume of work that a given computer handles is closely tied to the cost and to the memory size of the computer. Therefore, most authorities today accept rental price as the standard for ranking computers. Here, both memory size and cost shall be used to rank (classify) computers into three main categories as follows: 23 CIT 104 INTRODUCTION TO COMPUTERS  Microcomputers  Medium/mini/small computers  Large computer/mainframes. Microcomputers Microcomputers, also known as single board computers, are the cheapest class of computers. In the microcomputer, we do not have a Central Processing Unit (CPU) as we have in the larger computers. Rather we have a microprocessor chip as the main data processing unit. They are the cheapest and smallest, and can operate under normal office conditions. Examples are IBM, APPLE, COMPAQ, Hewlett Packard (HP), Dell and Toshiba, etc. Different Types of Personal Computers (Microcomputers) Normally, personal computers are placed on the desk; hence they are referred to as desktop personal computers. Still other types are available under the categories of personal computers. They are:  Laptop Computers: These are small size types that are battery- operated. The screen is used to cover the system while the keyboard is installed flat on the system unit. They could be carried about like a box when closed after operation and can be operated in vehicles while on a journey.  Notebook Computers: These are like laptop computers but smaller in size. Though small, the notebook computer comprises all the components of a full system.  Palmtop Computers: The palmtop computer is far smaller in size. All the components are complete as in any of the above, but it is made smaller so that it can be held on the palm. Uses of the Personal Computer A personal computer can perform the following functions:  It can be used to produce documents like memos, reports, letters and briefs.  It can be used to calculate budgets and accounting tasks  It can analyse numeric functions  It can create illustrations  It can be used for electronic mails  It an help in making schedules and planning projects  It can assist in searching for specific information from lists or from reports. 24 CIT 104 MODULE 1 Advantages of the Personal Computer  The personal computer is versatile: it can be used in any establishment  It has faster speed for processing data  It can deal with several data at a time  It can attend to several users at the same time, thereby being able to process several jobs at a time  It is capable of storing several data  Operating the personal computer gives less fatigue  It is possible to network personal computers, that is, linking of two or more computers. Disadvantages of the Personal Computer  The personal computer is costly to maintain  It is very fragile and complex to handle  It requires special skill to operate  With inventions and innovations everyday, the personal computer is at the risk of becoming obsolete  It can lead to unemployment, especially in less developed countries  Some computers cannot function properly without the aid of a cooling system, e.g. air conditioners or fans in some locations. Mini Computers Mini computers have memory capacity in the range ‘128- 256 Kbytes’ and are also not expensive but reliable and smaller in size compare to mainframe. They were first introduced in 1965; when DEC (Digital Equipment Corporation) built the PDP – 8.Other mini computers are WANG VS. Mainframe Computers The mainframe computers, often called number crunchers have memory capacity of the order of ‘4 Kbytes’, and are very expensive. They can execute up to 100 MIPS (Meanwhile Instructions per Second). They have large systems and are used by many people for a variety of purposes. 4.0 CONCLUSION Computers are classified based on three major criteria namely size, type of signal being processed, and purpose. The classification adopted at any 25 CIT 104 INTRODUCTION TO COMPUTERS point in time depends on the issues involved. For instance, if our goal is to process different kinds of signals or to accept one type of signal and convert to another form of signal, we should look in the realm of analog or digital or even the hybrid computers. This, of course, calls for a converter such as analog to digital converter or digital to analog converter as the case may be. 5.0 SUMMARY In this unit we have been able to study the following:  Computers can be classified based on three major criteria: size, type of signal being processed, and purpose.  Based on size, computers are classified as mainframe, mini computer and microcomputer.  Based on the type of signal being processed, computers are classified as analog, digital and hybrid.  Based on purpose, computers are classified as general-purpose or special-purpose computers.  Microcomputers now come in different forms due to the continued reduction in size as a result of advances in electronic technology. Microcomputers could be desktop, laptop or palmtop. 6.0 TUTOR-MARKED ASSIGNMENT 1. Classify computers based on type of signal. 2. Based on the signal being processed, to what category each of these computing equipment belongs: petrol pump, thermometer, cellphone, anti-aircraft radar control in the military, and weather forecasting equipment at the meteorological station. 7.0 REFERENCES/FURTHER READINGS Akinyokun, O.C, (1999). Principles and Practice of Computing Technology. Ibadan: International Publishers Limited. Balogun, V.F., Daramola, O.A., Obe, O.O., Ojokoh, B.A., and Oluwadare, S.A., (2006). Introduction to Computing: A Practical Approach. , Akure: Tom-Ray Publications. Larry Long (1984). Introduction to Computers and Information Processing. New Jersey: Prentice-Hall Inc. Gray S. Popkin and Arthur H. Pike (1981). Introduction to Data Processing with BASIC (2nd ed). Boston: Houghton Mifflin Company. 26 CIT 104 MODULE 2 MODULE 2 COMPUTER HARDWARE Unit 1 Hardware Components (1) Unit 2 Hardware Components (2) – Peripheral Devices Unit 3 Auxiliary Equipment UNIT 1 HARDWARE COMPONENTS (1) CONTENTS 1.0 Introduction 2.0 Objectives 3.0 Main Content 3.1 The System Unit 3.2 The Front of the System Unit 3.3 The Back of the System Unit 3.4 Inside the System Unit 4.0 Conclusion 5.0 Summary 6.0 Tutor-Marked Assignment 7.0 References/Further Reading 1.0 INTRODUCTION Your personal computer (PC) is really a collection of separate items working together as a team, with you as the captain. Some of these components are essential; others simply make working more pleasant or efficient. Adding extra items expands the variety of tasks you can accomplish with your machine. 2.0 OBJECTIVES At the end of this unit you should be able to:  identify the components of the computer  explain the importance of each component of the computer. 3.0 MAIN CONTENT 3.1 The System Unit The system unit is the main unit of a PC. It is the computer itself while other units attached to it are regarded as peripherals. It could be viewed as the master conductor orchestrating your PC’s operation. It is made up 27 CIT 104 INTRODUCTION TO COMPUTERS of several components like the motherboard, processor, buses, memory, power supply unit, etc. This unit (the system unit) has been confused over the years by novices as the CPU. This is not true. The CPU (Central Processing Unit) or simply processor is a component within the system unit and is not the only thing that makes up the system unit. Hence, it will be wrong to equate the system unit with the CPU. 3.2 The Front of the System Unit Lights Your unit may display a variety of coloured lights on the front panel, including power and turbo signals, and light to indicate if the hard or floppy disk is being read or written to. Key Lock You can stop intruders from tampering with your PC by using the lock on the front panel. Turning the key prevents the keyboard from working. Turbo Button Some PCs offer a choice of speeds at which they can run. A turbo switch is usually left so the computer runs at its fastest speed. Reset Button If your PC “freezes” and won’t respond to any command, try starting it up again using the reset button. Pressing the reset button loses all the work you have not saved in that session, so use it only as a last resort. Power On/Off All PCs have main power switch on the system unit. Sometimes this control is placed on the outside back panel. Floppy Disk Drives Either, or both, of two standard types of floppy disk drive may be found at the front of the system unit. Some systems also have internal CD- ROM or tape drives. 28 CIT 104 MODULE 2 Fig. 3: CD-ROM or DVD drive 3.3 The Back of the System Unit The Fan Housing The electronic components in your PC generate a lot of heat. To prevent overheating, a fan at the back of the unit removes hot air from the system. Power “in” and “out” Sockets Cables plugged into these sockets carry power from the electrical outlet to the system unit and from the system unit to the monitor. The Joystick Port Using a joystick is often much better than pressing keys to control movements when playing a computer game. Serial Ports Serial ports often connect the PC to the modem or mouse. Most PCs are fitted with two serial ports that may be labeled “S101” and “S102”, “Serial 1” and “Serial 2”, or “COM 1” and “COM 2”. Sound Jacks If you have a sound fitted inside your system unit, you will see a jack or jacks at the back. These can be used to connect your PC to speakers, a microphone, or an external sound source. 29 CIT 104 INTRODUCTION TO COMPUTERS The Keyboard Port The cable from your keyboard ends with a round connector, which plugs into the keyboard port. The Network Adapter If an expansion card is fitted to link your PC with other PCs in your office you will see a network connector at the back of the system unit. The Monitor Port A cable from your monitor plugs into this port and carries display information to the monitor. Bays for Expansion Cards PCs are easily expanded, perhaps to provide modem, sound or faster graphics. You can plug cards into expansion slots inside the PC. The end of an expansion card shows at the back of your machine, allowing you to connect items. 3.4 Inside The System Unit Fig. 4: Inside the system unit The brain behind everything that happens in your PC is contained within the system unit. Inside the unit are the impressive electronics that run programs, handle instructions, and determine the results. Most of the more important items are described below. 30 CIT 104 MODULE 2 The Battery A small battery powers a clock to keep track of the time when the PC is turned off. It also maintains low electricity to certain RAM chips that record which components are installed. The Disk Drive Controller Card This card controls the PC’s disk drive motors and transfers data. The serial and parallel ports at the back of the card link internal PC components with external devices such as mouse and printer. The Display Adapter Card (Video Card) All the information your computer will display is stored in its memory. To be useful, you need to see the information. The display adapter card is the link between the PC’s memory and the monitor. Expansion Slots These long narrow connectors allow you to plug in expansion cards (also known as adapter cards), which offer extra options not available on a basic PC. ROM Chips Read-only memory (ROM) chips have data written on them during manufacturing that tells the CPU what to do when the PC is switched on. The data is always there, even when you switch the PC off. RAM Chips When a computer is switched on and is running a program, RAM (Random Access Memory) is used for purposes such as holding the program and its data. But when the PC is switched off, anything held in RAM is lost. Empty RAM Chip Slots These slots let you expand your computer’s memory by adding extra RAM chips or modules. Some PCs work even faster because they come equipped with Cache Memory. Cache memory consists of expensive and very fast memory chips that store the data or instructions that the CPU will look at next. Cache memory can speed up work on your computer enormously. 31 CIT 104 INTRODUCTION TO COMPUTERS Fig. 5: A RAM chip The Central Processing Unit (CPU) Fig. 6: An Intel processor The microprocessor, or central processing unit (CPU), is the computer’s most important single item. It does all the PC’s thinking and runs the programs (series of instructions) that you request. CPU Support Chips These chips help the CPU manage all the other parts of the computer. The Math Coprocessor Slot A math coprocessor, present in some PCs, assists the CPU in its number-crunching activities (if programs have been designed to use it). 32 CIT 104 MODULE 2 Fig. 7: The CPU fan The Speaker The speaker emits the computer’s sound output. The Power Supply Unit All the components in a PC need electrical supply. Most need a 5-volt supply although floppy disk drive motors require 12 volts. If the components were connected to normal household current, they would blow up, so the power supply unit converts high voltage electrical current to a low voltage. The Hard Disk Drive The hard disk is your computer’s main permanent storage unit, holding large amount of data and programs. Unlike data held in RAM, the information on the hard disk is not affected when the PC is turned off – it remains there unless you instruct the PC to overwrite it or the hard disk is damaged. 33 CIT 104 INTRODUCTION TO COMPUTERS Fig. 8: The hard drive (Hard disk) The Motherboard All the electronic components in a PC are mounted on a piece of fiberglass called the motherboard. Fiberglass cannot conduct electricity, so each component is insulated from all the others. Thin lines of metal on the surface of the fiberglass connect pins from one component to another, forming the computer’s electrical circuits. 34 CIT 104 MODULE 2 Fig. 9: Components of a motherboard Intel CPUs The earliest PCs were equipped with a CPU from Intel Corporation called the 8088. The next generation of PCs used CPU known by the number “80286” and were called “PC/AT” computers. Subsequently, PCs have been supplied with more and more powerful CPUs – the 80386, the 80486, and the more recent and impressive of all, the Intel Pentium (I, II, III, IV& M). All these PC processors belong to a family called 80 x 86. In general, you can run the same software on PCs containing different CPUs within this family. From the outside, the chips look different only in sizes and number of pin-put inside. An 80486 has over one million components to the 3,500 that were in the first 8088. Because of these differences, the latest Pentiums runs over ten times faster. What is the CPU The CPU is certainly the most important PC component. CPU stands for Central Processing Unit. Let us briefly study that name:  It is a processor, because it processes (moves and calculates) data.  It is central, because it is the centre of PC data processing.  It is a unit, because it is a chip, which contains millions of transistors. 35 CIT 104 INTRODUCTION TO COMPUTERS CPU Speed The speed of a CPU is measured in megahertz (MHz). A computer has a central clock that keeps all the components in time with each other; one hertz is similar to a clock tick and megahertz is equal to one million ticks per second. If your PC runs at 333 or 400MHz, the central clock ticks 333 or 400 million times every second. As you might imagine, the faster the clock ticks, the faster the computer runs. Without the CPU, there would be no PC. Like all other hardware components, CPUs are continually undergoing further development. You can see the explosive technological development in data processing most clearly in the development of newer and faster CPUs. The CPUs have for years doubled their performance about every 18 months and there are no indications that this trend will stop. When we now look at all the CPUs from a broader perspective, we can see that:  The CPU history is closely tied to the companies IBM and, especially, Intel.  The CPUs have their roots back to Intel's chip 4004 from 1971.  The compatibility concept has been important throughout the development. Generations of CPUs There are CPUs of many brand names (IBM, Texas, Cyrix, AMD), and often they make models which overlap two generations. This can make it difficult to keep track of CPUs. Here is an attempt to identify the various CPUs according to generations: History of CPUs The following table shows the different CPU generations. 36 CIT 104 MODULE 2 Table 1: Different Generations of the CPU PC CPUs Year Number of Transistors 1st Generation 8086 and 8088 1978- 29,000 81 2nd Generation 80286 1984 134,000 3rd Generation 80386DX and 80386SX 1987- 275,000 88 4th Generation 80486SX, 80486DX, 1990- 1,200,000 80486DX2 and 80486DX4 92 5th Generation Pentium 1993- 3,100,000 Cyrix 6X86 95 -- AMD K5 1996 -- IDT WinChip C6 1996 3,500,000 1997 Improved Pentium MMX 1997 4,500,000 5th Generation IBM/Cyrix 6x86MX 1997 6,000,000 IDT WinChip2 3D 1998 6,000,000 6th Generation Pentium Pro 1995 5,500,000 AMD K6 1997 8,800,000 Pentium II 1997 7,500,000 AMD K6-2 1998 9,300,000 Improved 6th Mobile Pentium II 1999 27,400,000 Generation Mobile Celeron 18,900,000 Pentium III 9,300,000 AMD K6-3 ? Pentium III CuMine 28,000,000 7th Generation AMD original Athlon 1999 22,000,000 AMD Athlon Thunderbird 2000 37,000,000 Pentium 4 2001 42,000,000 37 CIT 104 INTRODUCTION TO COMPUTERS An Intel processor DISKS Floppy Disks Computers use disks to store information. Although there is a permanent hard disk that lives inside the system unit, you can use floppy disks to store and move data easily from one PC to another. Floppy disks come in two sizes, either 5¼ or 3½ inches in diameter. The smaller disks are able to store more data and are also less easily damaged, because of their thicker plastic cases. As both sizes can be either “high” or “low” capacity (or density), there are four main varieties of disks available. High-capacity disks are more expensive, but they can store much more information. Low-capacity disks are generally labeled DS/DD, which stands for “double sided/double density”, while the high- capacity floppy disks are labelled DS/HD (double sided/high-density). Caring for Disks Treat floppy disks carefully, and you can take them almost anywhere safely. Don’t leave the disks in your PC when you finish a session. Also avoid putting anything heavy on top of your disks or leaving them in extremes of hot or cold temperature. Try not to carry disks loose in pockets or handbags where dust and dirt may get inside the containers. Take care to store them vertically, preferably in a special storage box. Remember too that you should keep floppy disks away from magnetic fields, including hidden magnets such as those in telephone, radio and television speakers, amplifiers, desk fans, and photocopiers. If you do leave floppy disks near a magnetic field, your data may become corrupted and will no longer be usable. 38 CIT 104 MODULE 2 Write Protecting Disks Write-protecting a disk means that you prevent the computer from erasing or writing over important data or programs that are already there. However, the PC can still read a write-protected disk. 4.0 CONCLUSION The system unit is a box housing many components. It is, in fact, the most important part of the computer because it houses the processor (CPU) and other essential components that enables the computer to function. 5.0 SUMMARY We have studied the components of the system unit which include the components in the front, the back and those that are inside the unit. 6.0 TUTOR-MARKED ASSIGNMENT 1. Make a list of five components that could be found inside the computer systems unit. 2. Describe the functions of each of them. 3. Differentiate between the CPU and the system unit. 7.0 REFERENCES/FURTHER READING Akinyokun, O.C. (1999). Principles and Practice of Computing Technology. Ibadan: International Publishers Limited. Balogun, V.F., Daramola, O.A. Obe, O.O. Ojokoh, B.A., and Oluwadare S.A.. (2006). Introduction to Computing: A Practical Approach. Akure: Tom- Ray Publications. Richard H. Austin and Lillian Cassel (1986). Computers in Focus. Monterey, California: Books/Cole Publication Company. Larry Long (1984). Introduction to Computers and Information Processing. Prentice-Hall Inc. New Jersey. 39 CIT 104 INTRODUCTION TO COMPUTERS UNIT 2 HARDWARE COMPONENTS (2) – PERIPHERAL DEVICES CONTENTS 1.0 Introduction 2.0 Objectives 3.0 Main Content 3.1 Input Devices 3.1.1 The Computer Keyboard 3.1.2 The Mouse and Joystick 3.2 Output Devices 3.2.1 Printers 3.2.2 Monitors 3.2.3 Scanners 3.2.4 Speakers and Sound 4.0 Conclusion 5.0 Summary 6.0 Tutor-Marked Assignment 7.0 References/Further Reading 1.0 INTRODUCTION The computer peripheral devices are those devices which are attached to the system unit. The devices are necessary to ensure that the computer is able to accept input and display the result for the user. This section therefore discusses the input unit and the output unit. 2.0 OBJECTIVES At the end of this unit you should be able to:  identify those components that make up the input unit and the output unit of the computer  explain the functions of the input and the output units of the computer  identify and explain the type of input unit and output unit suitable to a particular computing environment. 40 CIT 104 MODULE 2 3.0 MAIN CONTENT 3.1 Input Devices 3.1.1 The Computer Keyboard A computer keyboard is identical to the conventional typewriter keyboard. However, it has more keys than the typewriter keyboard. A computer keyboard can be a dummy type or intelligent type. A computer keyboard is considered to be intelligent if, in addition to performing the routine functions characteristic of a typewriter keyboard, it can initiate a series of actions for a computer to carry out by mere pressing a key or combination of two or more keys. Thus, an intelligent computer keyboard has a set of keys which, when one of them is pressed, the computer can be made to carry out a specific function. For example, the pressing of a key may cause the computer to display a menu list from which the user may be prompted to select one. The intelligent computer keyboard has four major divisions, namely: Function keys, Alphanumeric keys, Numeric keys and Control keys. In addition to the four types of keys, there are some special or important keys such as the following: (a) Return or Enter key (b) Escape key denoted by ESC (c) Control key denoted by CTRL (d) Alternate key denoted by ALT (e) Delete key denoted by DEL (f) Insert key denoted by INS (g) Backspace key (h) Shift key. Function Keys The effects of the functions keys are software package dependent. That is, they mean different translations depending on which software package one is running on the computer. The function keys are traditionally labeled F1, F2, F3, F4, F5, F6, F7, F8, F9, F10, F11 and F12. The function keys are often arranged to the left of the main keyboard in two columns or they are arranged in a row above the main keyboard. In most software packages, the function key F1 is used to run the HELP program. Word perfect, for example, uses F3 for HELP program and F1 to cancel the last command issued on the computer. The function keys F7 and F12 are used to save a text and block a section of a text respectively in word perfect. Function keys can be programmed to carry out the functions desired by a programmer. For 41 CIT 104 INTRODUCTION TO COMPUTERS example the function key F10 may be programmed to display menus. Thus, the operations of the function keys can be determined by the user or programmed by the software package being used at any point in time. Alphanumeric Keys The Alphanumeric keys can be likened with the conventional typewriter keys. They contain alphabetic characters, numeric characters and special characters such as comma, full stop, open bracket, close bracket, asterisk, semicolon, colon, question mark, and so on. Usually, each key carries a character at the lower part and another character at the upper part. The SHIFT key is used to switch on or off the lower and upper characters by the programmer. Cursor Control Keys The cursor marks the active or current spot on the screen. It is an indicator that tells the user where in the midst of a document the system is pointing to. It may be a rectangular bar of light or a blinking underscore. When a text is being typed, the cursor moves as the carriage on a keyboard moves and character are typed in. The cursor control keys include four directional arrow keys. Table 2: Control Keys and their Functions Control Key Functions Moves the cursor one line up. Moves the cursor one line down Moves the cursor one character to the right Move the cursor one character to the left. Home Moves the cursor to the beginning of a line or page Move the cursor to the bottom left of a page or to End the end of the current line in most text editors. Moves the cursor to the top of the next page in PGDN the document or text. For example, pressing this key while on page 5 of the text will place the cursor at the top of page 6 of the text. PGUP Moves the cursor to the top of the previous page. For example, if you are on page 3 of a document, pressing this key will place the cursor at the top of page 2 of the document. 42 CIT 104 MODULE 2 Other cursor control keys are Home, Page Up, Page Down, and End. These keys may be part of the numeric keypad or separated from the numeric keypad. Moving the cursor around on the screen is one of the most common tasks in an application program. In fact, cursor movement is so important in an application such as word processing that it can usually be accomplished by additional key-driven commands. The control keys and their functions are documented in Table 5.1. The Numeric Keypad The numeric keypad contains a set of keys required for typing or entering number digits 0, 1, 2, 3, 4, 5, 6, 7, 8, and 9 into the computer store. A numeric key is often activated by pressing the Numlock Key. The numeric keypad is also used in combination with the Alternate (Alt) key to produce extended characters. Extended characters are characters not normally found on most keyboards. For example, to produce the character alpha, denoted ‘’, one holds down the Alt key and presses 224; to produce character beta denoted by ‘’, one holds down the Alt key and presses 255; and to produce the pound sterling sign denoted by ‘₤’, one holds down the Alt key and presses 156. The Shift Key When the shift key is pressed, the capital letters on the alphanumeric keys are activated. It also serves as the activator of characters that are at the upper part of each alphanumeric key. The Shift key has no effects on itself; its effect are realised when some other keys are pressed. Thus, if one presses the shift key and then ‘equals’ sign key, the ‘plus’ sign which is at the upper part of the ‘equal’ sign is activated, and it then appears on the screen. The Caps Lock Key The Caps Lock shifts all alphabetic characters into the upper case (capital letters). Thus all characters typed are in lower case (small letters) when not pressed. The Alternate Key (Alt) The alternate key can be used in combination with numeric keys to generate characters not shown on the keyboard, that is, extended characters. For example, holding the Alt key down and pressing 228 produces the summation () sign; holding the Alt key down and pressing 235 produces the  sign. To restart or reboot your computer, press Alt, Ctrl and Del keys simultaneously. 43 CIT 104 INTRODUCTION TO COMPUTERS The Num Lock Key The Num Lock key activates the numeric keypad. Neither the Num Lock key nor the Caps Lock key affects the function keys. The Control Key (Ctrl) The control key is often used in most text mode to perform block operations like mass deletion, insertion and so on. For example, Ctrl + Y deletes a line in most text documents. It can also be used in combination with other keys to move the cursor to different locations in a text or document. In some application packages, the Alt, Ctrl and Shift keys are used in combination with the function keys to perform several operations. For example, in the Word Perfect word processing package, to centre a text, press Shift and F6; to print a text, press Shift and F7. The Escape Key (Esc) The escape key cancels an operation in progress. For example, when one is editing a file or issuing a command, Esc cancels any changes one might have made or terminates the command. The Return or Enter Key The return key serves as one of the most important keys on most keyboards. It is actually used to inform the computer of the end of an input or command. It performs two functions depending on the program on which it is used. For example, suppose you are asked to respond to an operating system command at the prompt or other entries, the operating system will wait until the return key is pressed before continuing. Pressing the return key also positions the cursor at the beginning of the next line (in text mode), which is the equivalent of pressing the carriage return on a typewriter. The Insert Key (Ins) Pressing the insert key puts one’s keyboard in the insert mode, pressing it again returns to the overstrike (type over) mode. In the insert mode, the characters one types are inserted at the cursor position, the character at the cursor position and all characters to the right shift to make room for them. In overstrike or type over mode, newly typed characters overwrite the characters at the current cursor position. In most applications, the insert mode is indicated by a symbol in the status line. 44 CIT 104

CIT 104 Introduction to Computers Course Guide PDF

Document Details

Tags

Related

Summary

Full Transcript

Upgrade to continue