Chapter 1 Introduction to Computer Systems and Organization PDF

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Chapter one of Introduction to Computer Systems and Organization...

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B Sc. Information Technology /B Sc. Business Information Technology BIT 2102

COMPUTER SYSTEMS AND ORGANIZATION

COURSE OUTLINE 1.0 Course Objectives At the end of the course, the student should be able to:  Categorize the different types of computers.  Explain the applications of computers to different fields and to explain the impacts of computers to the society.  Explain the characteristics and purposes of all the sub-units in a computer system.  Understand the number system; perform binary operation in arithmetic and the conversions to different basis.  Describe the various file organization techniques.  Understand the concept of computer viruses, their effects and control.  Understand the concepts of the operating systems, main components purpose Course Description: Classification of computers: size, types, and generations, Fundamentals of PCs: Hardware. Central Processing Unit (CPU), mother boards, hard disc and floppy disc: types, track, sector, cluster, access mode: sequential, random, indexed and access methods. Memories: types and classification; random access memory (RAM), read only memory (ROM), cache, virtual storage, memory capacity peripheral devices: printer, monitor and keyboard. Software: Operating systems. purposes, organization. ROM BIOS. role of ROM BIOS. software utilities. Information and data; bits and byte. Data representation: character codes, binary, octal, and hexadecimal numbers. . COURSE STRUCTURE CHAPTER 1: INTRODUCTION  History of computing  Evolution of computing machines  Distinguish 1 to 5 computer generations  Characteristics of Computer  Types of Computers  Uses of Computers CHAPTER 2: INTRODUCTION TO COMPUTER SYSTEMS  Use of computers. Hardware; input and Output devices and their characteristics. CHAPTER 3: COMPUTER HARDWARE:  Components of a Computer System. o Hardware; input and Output devices - an overview.  Mother boards,  Central processing unit (CPU),  Memory and storage devices,  Peripheral devices,  System bus. 1 | P a g e of 13

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CHAPTER 4: INPUT/OUTPUT METHODS AND DEVICES o External Storage, Floppy and hard disk storage, access time, block size and access speed. CHAPTER 4: FILES:  File types,  File organization;  Sequential,  Random,  Indexed and  File access methods. CHAPTER 5: COMPUTER SYSTEMS MEMORY/MEMORY HIERARCHY  Memory types and classification;  Random Access memory(RAM),  Read only memory(ROM),  Cache,  virtual storage,  memory capacity CHAPTER 6: REPRESENTATION OF DATA AND COMPUTER ARITHMETIC: 6.1 Some terminology and jargon used in the computing; Memory terms: Bit, Byte, Kilo, Giga, RAM, 6.2 Character codes ASCII etc 6.3 Number Bases and Conversions 1. Decimal, octal, hexadecimal and binary 6.4 Computer Arithmetic

Chapter 7: COMPUTER OPERATING SYSTEMS  Operating System: o Purpose, o Operation, o Main components, o Customizing the operating system, o Role of ROM BOIS.

CHAPTER 8: SYSTEM BUSES o Buses:  Internal and external buses,  Bus width and clock speed.  Bus Technology and standards:  Expansion bus standard – 15A/EISA/MCA/PC1/SCSI and PCI/SCSI and current trends. Teaching Methodology  Lectures and tutorials, Practical, Group discussions, Individual assignments Assessment  A learner is assessed through ; 2 | P a g e of 13

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Continuous Assessment Tests (CATs) (30%) End of semester examination (70%)

Course Assessment: A learner is assessed through;  Assignments, tutorials, tests, practical exercises and end of semester examinations i.e. 1. 2 CATS 20 Marks each & 1 make up cat Cat1 5th Week, Cat2 10th Week 2. 2 Written Assignment 10 Marks each 3. Lab assignment 10 marks to be assessed at 13th week 4. 1 written final examination 70 marks

Required Text BOOKS  Stallings Williams, Computer organization and Architecture, Pearson Education  Capron, H.L, Computers: Tools for an Information Age(5th Edition),  Addison Wesley Longman Inc Sunderland Keith, Understanding the internet: A clear Guide to internet Technologies, Butterworth Heinemann  Tanenbaum A.S, Structured computer organization, Prentice – Hall  French C.S, Handbook of computer science(5th Edition), O.P. Publications Limited Other support materials  Various application manuals and journals  Variety of electronic information resources as prescribed by the lecturer Lecturer: Patrick Ndungu

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CHAPTER 1: INTRODUCTION TO COMPUTER 1.0.  

What is a Computer The word “computer” comes from word compute, which means to calculate. “A computer  is a programmable machine (or more precisely, a programmable sequential state machine) that operates on data and is used for wide range of activities”.  An electronic device capable of accepting data as input, storing all the information relevant to it, processing the data in a predetermined way that conforms with a program of instructions and then communicating the results as output.  is an electronic device capable of data processing by use of sets of instructions called computer programs.

Thus, a computer system is made up of two major components i.e. Hardware and software. 

Hardware refers to the physical components that make up a computer system e.g. monitor, keyboard, system casing etc.

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Software refers to the programs which instruct the computer hardware on what to do and how to do it. Examples of software include operating systems and application programs.

Software can be broken further into three major areas: a) Systems Software – programs that manage the computer resources and ensure the normal running of the computer. E.g.  operating system: Utility programs – programs that perform repetitive tasks in day to day running of the computer system .e.g. format program, copy program etc. Note o Utility programs can either be part or not part of the operating system.  Translators:b) Application software – end user programs which enable the user to perform the tasks using a computer. E.g. Word processing software, accounting software etc. 1.1. ROLE OF COMPUTERS IN SOCIETY 

Computers have become the backbone of commercial and industrial activities.

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In modern offices, computers are now used for general office automation including text production, accounting services, desk-top publishing, stock control, point-of-sales systems etc. Today computers play a strategic role in business by defining new products and services maintaining a competitive edge and providing new opportunities for management control.

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Leading companies use computing technology as a competitive tool to develop new products and services forge new relationships with suppliers and edge out competitors. 4 | P a g e of 13

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Modern industries are equipped with production planning, scheduling and reporting computing systems that provide real-time information on production. It is, therefore very important for our society to embrace computing.

1.2 HISTORY OF COMPUTERS  The first computing machine was known as ABACUS. It was used in China and Japan, thousands of years BC.  John Napier developed the table of logarithms in 1614.  Later on in the 1620’s William Oughtred developed the slide rule based on the concept of logarithms.  In 1647, a French Mathematician, Blaise Pascal invented the Mechanical Calculator.  In 1694 G. W. Leibnitz a German Mathematician invented “Leibnitz’s stepped Reckoner. This was a more effective calculator than Pascal’s Mechanical calculator, and could add, subtract, multiply, divide and compute square roots.  In the nineteenth century, Charles Babbage of England made the most outstanding developments in computing.  In 1832, he developed a device called the “Analytical Engine” which was able to handle decision based arithmetic processes. The analytical engine was recognized as the milestone signifying the start of the computer age and Charles Babbage the father of the modern computer.  Later on with the coming of the technology of electrics after the discovery of the Silicon chip, electronic computers were developed over the years. Electronic computers have since been improved upon and are better examined through generations. 1.3 ELECTRONIC COMPUTER GENERATIONS First Generation: 1946 – 1956  The first generation of computers relied on vacuum tubes to store and process information. This consumes a great deal of power, were short-lived and generated a lot of heat.  Used magnetic drum memories the maximum memory size was approximately 2 Kilobytes with a speed of 10 Kilobytes or 10,000 instructions per second.  At around this time, Dr. John Van Newmann developed a computer architecture that is still used up to the present day and built the EDVAC (Electronic Discrete Variable Automatic Computer). This was the first computer that used instructions stored in memory. Second Generation: 1957 – 1963  Second generation computers relied on transistor technology invented in 1947 at Bell Laboratories, and magnetic core memories.  Computers were then built from individual transistors wired-up together. 5 | P a g e of 13

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 The first transistorized computer (TRADIC) contained 800 transistors and was built by Bell laboratories in 1954.  Transistors were much more stable and reliable than vacuum tubes, they generated less heat, and consumed less power.  Memory size expanded to 32 kilobytes and speeds up to about 300,000 instructions per second. Third Generation: 1964 - 1975  Third generation computers used integrated circuits which were made by combining several transistors usually 3 to 15 together.  Magnetic disk was developed during this period for storage purposes.  Computer memories expanded to 2 megabytes of RAM and speeds increased to 5 million instructions per second.  This period also saw the production of the first microcomputer which appeared in 1974.  We now had 8-bit microcomputers. Fourth Generation (1972-1984)  Large scale integration (LSI - 1000 devices per chip) and very large scale integration (VLSI - 100,000 devices per chip) were used in the construction of the fourth generation computers.  It marked by the use of microprocessor o Microprocessor – is a silicon chip that contains the CPU – part of the computer where all processing takes place. 

4004 chip – was the first microprocessor introduced by Intel Corporation.

o Whole processors could now fit onto a single chip, and for simple systems the entire computer (processor, main memory, and I/O controllers) could fit on one chip. Gate delays dropped to about 1ns per gate. o Core memories were replaced by semiconductor memories. Large main memories like CRAY 2 began to replace the older high speed vector processors, such as the CRAY 1, CRAY X-MP and CYBER Note 

In 1972, Dennis Ritchie developed the C language from the design of the CPL and Thompson's B. Thompson and Ritchie then used C to write a version of UNIX for the DEC PDP-11. Other developments in software include very high level languages such as FP (functional programming) and Prolog (programming in logic).

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IBM worked with Microsoft during the 1980s to start what we can really call PC (Personal Computer) life today. IBM PC was introduced in October 1981 and it worked with the operating system (software) called ‘Microsoft Disk Operating System (MS DOS) 1.0. Development of MS DOS began in October 1980 when IBM began searching the market for an operating system for the then proposed IBM PC and major contributors were Bill Gates, Paul Allen and Tim Paterson. In 1983, the Microsoft Windows was announced and this has witnessed several improvements and revision over the last twenty years.

Fifth Generation (1984-1990) 6 | P a g e of 13

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This generation brought about the introduction of machines with hundreds of processors that could all be working on different parts of a single program.

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The scale of integration in semiconductors continued at a great pace and by 1990 it was possible to build chips with a million components - and semiconductor memories became standard on all computers.

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Computer networks and single-user workstations also became popular.

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Parallel processing started in this generation.

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The Sequent Balance 8000 connected up to 20 processors to a single shared memory module though each processor had its own local cache.

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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.

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The Intel iPSC-1, also known as ‘the hypercube’ 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 problem and large systems with more processors (as many as 128) could be built.

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Also introduced was a machine, known as a data-parallel or SIMD where there were several thousand very simple processors which work under the direction of a single control unit. Both wide area network (WAN) and local area network (LAN) technology developed rapidly.

Sixth Generation (1990 - )  Most of the developments in computer systems since 1990 have not been fundamental changes but have been gradual improvements over established systems. 

This generation brought about gains in parallel computing in both the hardware and in improved understanding of how to develop algorithms to exploit parallel architectures.

 Workstation technology continued to improve, with processor designs now using a combination of RISC, pipelining, and parallel processing. Wide area networks, network bandwidth and speed of operation and networking capabilities have kept developing tremendously.  Personal computers (PCs) now operate with Gigabit per second processors, multiGigabyte disks, hundreds of Mbytes of RAM, colour printers, high-resolution graphic monitors, stereo sound cards and graphical user interfaces.  Thousands of software (operating systems and application software) are existing today and Microsoft Inc. has been a major contributor. Microsoft is said to be one of the biggest companies ever, and its chairman – Bill Gates has been rated as the richest man for several years. o Finally, 

this generation has brought about micro controller technology. 

Micro controllers are ’embedded’ inside some other devices (often consumer products) so that they can control the features or actions of the product.

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They work as small computers inside devices and now serve as essential components in most machines.

1.4 CLASSIFICATION OF COMPUTERS - BY SIZE a) Super computer  Super computers can process huge amounts of data 

They are biggest in size

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The most expensive in price than any other

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It can process trillions of instructions in seconds.

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This computer is not used as a PC in a home neither by a student in a college.

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Governments specially use this type of computer for their different calculations and heavy jobs.

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Different industries also use this huge computer for designing their products. In most of the Hollywoods movies it is used for animation purposes. This kind of computer is also helpful for forecasting weather reports worldwide.

b) Mainframes Another giant in computers after the super computer is Mainframe, which can also process millions of instructions per second and is capable of accessing billions of data. 

These are very large computers that require extensive space, and they are very expensive to buy and maintain.

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They are general purpose in nature and have very large computing power, which enable them to be capable of handling multiple simultaneous activities like batch processing, Interactive processing, transaction processing, all other under the control of an operating system that provide for scheduling and control facilities.

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Their main memory is large and they can store a lot of data and instruction. Their processing speed is high and they can only be used in large organization or institution where very large amount of information are been processed like banks, insurance companies, manufacturing firms, universities, etc. an example is IBM 370.

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They are normally too expensive and out of reach from a salary-based person who wants a computer for his home. This kind of computer can cost thousands of dollars.

c) Minicomputer This computer is next in line but offers less than mainframe in work and performance. 

These are the computers which are mostly preferred by the small type of business personals,

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colleges, etc. o Although, most of them are general purpose in nature, some are still been used for special or dedicated purposes. When compared with mainframes, their processing 8 | P a g e of 13

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speed is slower, their main memory smaller and their capability to support secondary storage system are lower but they are larger in the same terms than micro computers. They have the ability to handle complex calculations. d) Microcomputers Microcomputers are the smallest and the cheapest when compared with mainframes and mini computers. They are otherwise known as personal computers (PC) because they are designed as single user system. Their processing speed is the highest and their central processing units (CPU) consist of microprocessors placed on silicon chips. Present day micro computers are very complex, powerful, rugged, have very large storage capacity and some of them are very portable as we shall discuss the types of micro computers below. e) Desktops This is a microcomputer that is designed to fit on a desk. This means that they are intended for regular use at a single location. At a minimum, a central processing unit (CPU), a monitor, and a keyboard as separate units, connected by special cables The CPU can be housed in either a vertical or a horizontal case. f) Laptops They are equivalent to PCs in their functionality but, very small in size compared to PCs. They are portable, in the sense; you can carry them wherever you travel. They run on battery. As long as the battery can supply power, the laptops function. The monitor, keyboard, mouse, and storage devices are integrated as one device and get a common power supply. Advantage is, they are portable and handy. Basic disadvantages are, they are costly and theft prone. If you want to upgrade the existing configuration they proved to be still costlier. g) Notebooks A portable computer typically weighing less than 6 pounds (3 kilograms) that has a flatpanel display and miniature hard disk drives, and is powered by rechargeable batteries. Having a small size and low weight the notebook is easy to carry to anywhere. A student can take it with him/her to his/her school in his/her bag with his/her book. This is easy to carry around and preferred by students and business people to meet their assignments and other necessary tasks. The approach of this computer is also the same as the Personal computer. It can store the same amount of data and having a memory of the same size as that of a personal computer. One can say that it is the replacement of personal desktop computer. Among the best-known makers of notebook and laptop computers are IBM...