Computer Defined

Introduction to Computing A Journey Towards The Computing World This book provides the introduction to the basic concepts related to the computing field. It also provides you the brief and clean introductory class about various types of the computers. Author: Ali Asghar Manjotho 12/25/2007 A word about the Author and the Book This book is written, composed, and organized by Mr. Ali Asghar Manjotho — studying at Computer Systems Engineering Department under the kind umbrella of Mehran University of Engineering and Technology Jamshoro bearing the roll number (07CS20).

He started to receive his pre-primary and primary education at Mehran University Public School Jamshoro (Presently, Mehran University Higher Secondary Public School Jamshoro). Then he continued there up to secondary education level. After that he received the higher education from the Government Muslim Science College Hyderabad. Now presently he is continuing is Bachelors degree plan at Mehran University of Engineering and Technology Jamshoro in the Department of Computer Systems Engineering. This book, as its title elaborates, provides the introductory concepts and ideas about the computer field.

This book is designed to meet the needs of Introduction to various computing concepts including the various concepts about the computer itself, its types, its parts, and its components and so on. In order to provide you the clear and standardized definitions and ideas, this book gets the help from the encyclopedia. If you consider yourself limited in this book, you can take online help by browsing the web page www. wikipedia. com. This book has got clear formatting and arrangement of material in to it so you can analyze certain paragraph or section very easily.

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Introduction to computers 1 Computer The computer is an electronic device, which is capable of receiving input, processing the data according to the given set of instructions, producing output and also capable of storing huge amount of data permanently. Computer is so called an electronic device because a computer is simply a machine which operates on the electric signals. There are many types of computers but the primary job of every computer is to convert raw data in to the useful information by applying some processing on the raw data according to the given set of instructions. The computer receives the data from the user Figure 1. via input devices then it applies some processing on to it with Figure 1. 1 – A traditional Computer the help of processing devices (processor) and converts it into useful information then it shows that output on the output devices (like monitor or printer) and if requested it stores that processed data (information) on to any storage media (like hard disk or floppy disk etc) permanently so that it can be accessed by the user at any time. Computer is basically a calculating device but the ability to store and execute programs makes computers extremely versatile and distinguishes them from calculators.

Computer helps us doing certain jobs in split seconds that the human even can’t think of it. The computers are becoming the fundamental part of every field like they are widely used in industries, banks, insurance companies, universities, colleges, nuclear science, weather forecasting, weapon designing, car modeling, air crash investigation, Bio-medical sciences etc. because they perform specific tasks very quickly, accurately and very fast. The computers that we see all around us in schools, colleges, universities, and offices are digital computer.

As there are many different types of computers therefore computers can’t be classified in one or two categories. Computer can be classified in many aspects as according to type of data they can represent (i. e. Analog or Digital), according to the size, according to the data handling capabilities, according to the hardware they contain, according to the software they can support and many many more. Introduction to computers Classification of computers on the basis of size 1) Super Computers Super computers are the most powerful computers built by people.

These computers are the largest computers among the computers made since very starting ages. These computers can house thousands of processors and can handle the needs of thousands of users at a time. These computers can process huge amount of data. These computers are ideal for solving very large and complex problems which required extreme calculation power. Supercomputers are used for highly calculation-intensive tasks such as problems involving quantum mechanical Figure 1. 2 2 physics, weather forecasting, climate research (including Figure 1. – NASA’s Supercomputer research into global warming), molecular modeling (computing the structures and properties of chemical compounds, biological macromolecules, polymers, and crystals), physical simulations (such as simulation of airplanes in wind tunnels, simulation of the detonation of nuclear weapons, and research into nuclear fusion), cryptanalysis, major universities, military agencies and scientific research laboratories are heavy users. The speed of super computers is measured in FLOPS (Floating Point Operations Per Second) or TFLOPS (1012 FLOPS).

IBM’s BLUE Gene/L developed on March 25, 2005 is today’s fastest super computer. At that time it ran at 135. 5 TFLOPS (1012 FLOPS) but on October 28, 2005 the machine reached 280. 6 TFLOPS. Some of the powerful super computers made are: IBM NORC in 1954 at U. S. Naval Proving Ground, Dahlgren, Virginia, USA. UNIVAC LARC in 1960 at Lawrence Livermore National Laboratory, California, USA. CDC 6600 in 1964 at Lawrence Livermore National Laboratory, California, USA. Burroughs ILLIAC IV in 1975 at NASA Ames Research Center, California, USA.

Intel Paragon XP/S 140 in 1993 at Sandia National Laboratories, New Mexico, USA. Hitachi SR2201/1024 in 1996 at University of Tokyo, Japan. NEC Earth Simulator in 2002 at Earth Simulator Center, Yokohama-shi, Japan. Introduction to computers IBM Blue Gene/L in 2005 at U. S. Department of Energy/IBM, USA. 3 Cray Inc. , Fujitsu, Groupe Bull, CDAC, IBM, Infiscale, Microsoft, nCUBE, NEC Corporation, Quadrics, Sun Microsystems and SGI are some of the companies who manufacture super computers. 2) Mainframe Computers

Mainframes (often referred as Macro computers or Big Iron) are computers used mainly by large organizations for critical applications, typically bulk data processing such as census, industry and consumer statistics and financial transaction processing. These are large and power computers but have less power than super computers. The early mainframes were so large that they were housed in enormous, room-sized metal boxes or frames. But today’s mainframes are smaller than that of early mainframes. Figure 1. 3 Figure 1. 3 – Mainframe Computer In the 1960s, most mainframes had no interactive interface.

They accepted sets of punch cards. By the early 1970s, many mainframes acquired interactive user interfaces and operated as timesharing computers, supporting hundreds or thousands of users simultaneously. Users gained access through specialized terminals or, later, from personal computers equipped with terminal emulation software. Many mainframes supported graphical terminals (and terminal emulation) by the 1980s. In 1990, an IBM mainframe became the first Web server located anywhere outside Switzerland’s CERN organization.

Mainframe computers are very large and powerful computers and can handle the processing needs of thousands of users at a time. But these systems lake in flexibility i. e. they are only used for specific tasks like, the mainframe in a Air-lines can only store the information about the schedules of flights, the data about the visas an passports of passengers, the record of the passengers etc means mainframe computers are not so much flexible. The speed of the mainframe computers is measured in MIPS (Millions Of Instructions Per Second).

IBM System z9, Burroughs large systems and the UNIVAC 1100/2200 series are some examples of mainframe computers. Some of the companies that manufacture the mainframe systems are IBM, Hewlett-Packard, Sperry, Burroughs, Fujitsu, Hitachi and Groupe Bull. Introduction to computers 3) Minicomputers 4 Minicomputers were evolved in 1960’s. These are Figure 1. 4 smaller and less powerful than mainframe computers but still they can offer huge processing capabilities. They usually took up one or a few cabinets the size of a large refrigerator.

The first successful minicomputer was Digital Equipment Corporation’s 12-bit PDP-8, which cost from US$16,000 upwards when launched on March 22, 1965. It was designed by W. A. Clark and C. E. Molnar. The earliest PDP-8 model is also called Straight-8 because it used discrete transistor technology, packaged on flip chip cards, and was approximately the size of a compact Figure 1. 4 – Minicomputer refrigerator. This was followed by the PDP-8/S. By using a one-bit serial ALU implementation, the PDP-8/S was smaller, less expensive, but vastly slower than the original PDP-8.

After this the family of PDP-8 computers continued and included PDP-8/I, PDP8/L, PDP-8/E, PDP-8/F, PDP-8/M and PDP-8/A. Minicomputers are also known as midrange computers because their capabilities lie in between that of mainframes and microcomputers (Personal Computers). Minicomputers can handle huge processing than microcomputers. The minicomputers can handle the processing needs of hundreds of users at a time. The user can access the central minicomputer through a terminal or standard PC. Figure 1. 5 Some examples of minicomputers are: Control Data’s CDC 150A and CDC 1700,

DEC, PDP and VAX series , Data General Nova , Hewlett-Packard’s HP3000 series , Honeywell-Bull Level 6/DPS, 6/DPS 6000 series , IBM midrange computers , Norsk Data Nord-1, Nord-10, and Nord-100 , Prime Computer Prime 50 series , SDS SDS-92 and Wang Laboratories 2200 and VS series . IBM and Digital Equipment Corporation are the leading minicomputer manufacturers. Other companies who contribute are Data General, Prime, Computervision, Honeywell and Wang Computer. Figure 1. 5 – Minicomputer Introduction to computers 4) Microcomputers 5 Microcomputers, as their name implies, are the smallest computers built for the users.

These computers are so small that they can sit under or inside a desk or table some computer even can easily fit in to your hand or pocket. Microcomputers are so called because they contain a microprocessor (µP) as its CPU and another general characteristic of these computers is that they occupy physically small amounts of space. These are the computers which we see all around us in offices, homes, schools, colleges and universities. These computers are designed to be used by a single person at a time therefore these are also known as personal computers (PCs).

The microcomputer came after the minicomputer, most notably replacing the many distinct components that made up the minicomputer’s CPU with a single integrated microprocessor chip. The early microcomputers were primitive, the earliest models shipping with as little as 256 bytes of RAM, and no input / output other than lights and switches. However, as microprocessor design advanced rapidly and memory became less expensive from the early 1970s onwards, microcomputers in turn grew faster and cheaper. This resulted in an explosion in their popularity during the late 1970s and early 1980s.

Today’s typical microcomputer usually comes with a system case which includes main critical circuitry as, the motherboard, microprocessor, RAM, video card, sound card, networking card/modem, hard disk drive, floppy disk drive, CD-Rom, power supply and many other components. It also contains a monitor and input/output devices like, keyboard and mouse. Today’s microcomputers are very small then the microcomputers of early 1990’s. The early microcomputers include Apple II, Commodore 64, BBC Micro, and TRS 80. There are six categories of microcomputers: 1. Desktop Computers 2. Workstations 3. Notebook computers 4. Tablet PCs 5.

Handheld Computers 6. Smart Phones Introduction to computers Desktop Computers Desktop computers are the most popular personal computers. These computers are designed to sit under or inside a desk or table. These are the computers which we see all around us in homes, office and colleges. These computers are very flexible and can perform a wide variety of tasks like they are widely used in homes for playing computer games, editing videos, creating office notes and documents, chatting through internet, sending e-mails, or playing music etc. Figure 1. 6 6 These computers contain a monitor for output, a keyboard or mouse Figure 1. – Desktop for inputting usually both, a system unit which contains all the Computer critical circuitry of the system, pair of speaker for sound output and many other devices. The main component of desktop computers is the system unit, which is the box containing all the critical circuitry like, mother board, microprocessor, RAM, hard drives, optical storage drives, floppy drives, power supply etc. The system unit comes in two basic models one is the horizontally oriented desktop model which sits flat on the surface horizontal and some users prefer placing monitor on the top of the system unit.

Another is the vertically oriented tower ATX model, which sits vertically next to the monitor. It is the most popular model among the geeks of computers. Workstations A workstation is a high-end desktop or deskside Figure 1. 7 microcomputer designed for technical applications. Workstations are intended primarily to be used by one person at a time, although they can usually also be accessed remotely by other users when necessary. Workstations usually offer higher performance than is normally seen on a personal computer, especially with respect to graphics, processing power, memory capacity and multitasking ability.

Workstations are often optimized for displaying and manipulating complex data Figure 1. 7 – High-end Workstation such as 3D mechanical design, engineering simulation results, and mathematical plots. Workstations have a high resolution monitor, accelerated graphicshandling capabilities. These systems are ideal for advanced architecture, engineering design, animations. Workstations are popular for engineering and scientific field applications. Perhaps the Introduction to computers 7 irst computer that might qualify as a “workstation” was the IBM 1620, a small scientific computer designed to be used interactively by a single person sitting at the console. It was introduced in 1959. Other types include Lisp machines developed at MIT around 1974, the famous Xerox Star (1981) and the less well known Three Rivers PERQ (1979). Some of the companies who contributed in manufacturing workstations are: IBM, Digital Equipment Corporation, Hewlett Packard and Sun Microsystems. Notebook Computers Notebook computers are very small computers that can be fit easily Figure 1. 8 on your lap.

These computers are full-featured computers which offer same capabilities as found in traditional desktop PC. These computers are approximately same size and shape of a notebook therefore they are also called notebook computers. These computers look like a briefcase, which carries the important data. These computers are also called laptop computers because peoples can set these devices on their laps easily. These computers are very light and weight 2. 2-18 pounds (1-6 kilograms), depending on size, materials, and other factors. These computers operate on Figure 1. 8 – Notebook Computer a small battery which can be recharged.

It is possible to run these full-features computers on a small battery because the circuitry of this computer is very small and the more important factor is that they use LCD (Liquid Crystal Display) monitor, which operates at very low electric power and run cooler than CRT (Cathode Ray Tube) monitor. These computers can also be operated with A. C current by using an AC/DC adapter. To use this computer you open the lid of this device and it reveals a small built-in keyboard and LCD monitor and when you want to close it you close the lid and the device folds itself for easy carrying.

Today’s typical notebook computers also contain a built-in trackpad as a pointing device, rather than mouse or trackball, located usually between G, H, and B keys on the keyboard. The main advantage of these computers is that they are very small and can be carried around easily and due to this portability these computers lie in the category of mobile computers. Beside this they also offer built-in keyboard and monitor, which makes them ideal for office workplaces. You can also connect the notebook computer to a full-sized keyboard, mouse and monitor.

Today’s most popular notebook is Lenovo ThinkPad. The companies who manufacture laptop computers include: Toshiba, Sony, Lenovo, Dell, BenQ, Panasonic, Samsung, Gate Way, LG, Compaq and others. Introduction to computers Tablet PCs 8 Tablet PCs also referred as shrunken notebook computers lie Figure 1. 9 in the category of mobile computer. Tablet PCs are the computers, smaller and lighter than a notebook computer. These are portable computers and can be carried around easily from one place to another. These computers offer same functionality as offered by a traditional notebook computer.

Tablet PCs have a touch screen which accepts the input with special pen called as digital pen or stylus; or with the finger touch instead of keyboard or mouse. You can directly tap or write on to the screen with the help of this pen. A software known as handwriting recognition is installed in the Tablet PC which matches the inputted text with its own stored Figure 1. 9 – Tablet PC assumptions and converts it into computer’s own fonts. Few newer models of Tablet PCs also offer a built-in microphone which accepts the input from the user’s voice and special software speech recognition software which converts t into the text or commands. Some models also offer a small miniature built-in fold-out keyboard, which you can use as you use in a traditional desktop PC. These small devices can also be connected to a full-sized keyboard and monitor. Tablet PCs use their own operating system like, Windows XP Tablet PC Edition. Major Tablet PC manufacturers include Acer, Asus, Fujitsu, Gateway, Inc. , Hewlett-Packard, IBM, Lenovo Group, LG Electronics, Motion Computing, TabletKiosk, NEC, Nokia (e. g. 770 and N800), Panasonic, Sony-Ericsson and Toshiba.

Popular models of Tablet PCs include: Fujitsu Stylistic ST5000 , Electrovaya Scribbler SC2000, SC3000, SC3100 , MobileDemand xTablet , T8600 Rugged Tablet PC , Motion M1200, M1300, M1400, LE-Series, C5, LS800 , NEC Versa LitePad , Panasonic Toughbook 08 , TabletKiosk Sahara i215 (i412T, i440T and i440D announced Feb 2007) , Samsung Q1 , Nokia 770 and N800 , SonyEricsson P990 , Acer TravelMate C200/C300/C310 , Asus R1F, Averatec C3500 Series , Fujitsu LifeBook P1510(Slim, Ultra-portable, Small)/T4020, /T4210, /T4220 (Latest) , Gateway CX210/M285/S7200 , HP Compaq TC4200/TC4400 , HP TX1000/TX1020 , Lenovo ThinkPad X41 , Lenovo ThinkPad X60 Tablet (known popularly as “X60t”) , Lenovo ThinkPad X61 Tablet , LG XNote C1 , LG LT-20-47CE , Panasonic Toughbook 19 , Toshiba Portege 3500/M200/M400/M405/R400 , Toshiba Satellite R10/R15/R20/R25 , Toshiba Tecra M4/M7 , Compaq TC1000 , HP Compaq TC1100 and Fujitsu-siemens lifebook T and P series. Introduction to computers Handheld PCs 9 Handheld computers are very small devices enough to fit in Figure 1. 10 your hand therefore these devices are also called palmtop computers. There devices are even smaller and lighter than Tablet PCs. There are many types of handheld computers but the most popular is Personal Digital Assistant (PDA). It is very small pocket-sized device and can be fitted in to your front or side pocket easily.

It is widely used to take notes, display telephone and fax numbers and to display e-mail addresses. These devices are ideal for taking very small data and can not handle very huge amount of data as a traditional personal Figure 1. 10 – PDA (Personal Digital computer does. These devices like tablet PCs use a digital pen Assistant) for inputting the data and some also come with a built-in microphone to allow the users to input the sound data. These devices also offer many other features as, cellular phone, camera and music player. These devices can be connected to the Internet wirelessly and you can also connect them to a full-sized computer to share the data. Smart Phones

Smart phones are full-featured mobile computers with personal computer like functionality. These are cellular phones which offer many other features which are not found in traditional cellular phone like, web and email access, special software such as personal organizer, special hardware as digital camera and music player. These are the features that are not the part of a traditional cellular phone therefore these devices lie in the category of smart phones. Some models also offer a built-in miniature QWERTY keyboard. These smart phones use different operating system as Symbian OS from Symbian Ltd, Windows Mobile from Microsoft, Palm OS and Rim BlackBerry OS.

Some models of smart phones are Apple iPhone, Motorola RIZR Z8, Nokia E61i, Nokia E70, Nokia N95, Palm Treo 700p, RIM BlackBerry 8700c, Samsung SGH-i607 BlackJack, Sony Ericsson P990, Sony Ericsson W950i and Figure 1. 11 – Smart Phone Figure 1. 11 Introduction to computers Samsung SCH-i730. 10 Some major manufacturers of smart phone are Gigabyte, Group Sense PDA, Hewlett-Packard, High Tech Computer (HTC), I-mate, Kyocera, Mio Technology, Motorola, Nokia, Palm Inc, Research in Motion Limited (RIM), Samsung Electronics and Sony Ericsson. Classification of computers on the basis of type of data used OR on the basis of their working principles Analog Computers Analog computers (spelled analogue in British English) are the form of computers which use electrical, mechanical or hydraulic phenomena to solve the problems.

More generally an analog computer uses one kind of physical quantity to represent the behavior of another physical system, or mathematical function. Analog computers are the computers, designed to perform arithmetical functions upon the numbers, where the numbers are responded by some physical quantity like, temperature and voltage (which vary continuously). Analog computers operate by only measuring rather than by counting. These computers are used for scientific and engineering problems. Time line of analog computers 1) The slide rule is a hand-operated analog computer for doing multiplication and division, invented around 1620–1630, shortly after the publication of the concept of the logarithm. ) The differential analyser, a mechanical analog computer designed to solve differential equations by integration, using wheel-and-disc mechanisms to perform the integration. Invented in 1876, they were first built in the 1920s and 1930s. 3) In World War II era gun directors and bomb sights used mechanical analog computers. 4) General Precision Systems electronic analog computer in 1950 was a very adaptable machine that could be configured to solve a range of problems. 5) The MONIAC Computer was a hydraulic model of a national economy built in the early 1950s 6) Heathkit EC-1 an educational analog computer made by the Heath Company, USA in 1960. Introduction to computers

Some examples of analog computers constructed and practically used are: 11 Antikythera mechanism, Astrolabe, Differential analyzer, Kerrison Predictor, Mechanical integrator, MONIAC Computer (hydraulic model of UK economy), Nomogram, Norden bombsight, Operational amplifier, Planimeter, Rangekeeper, Slide rule, Torpedo Data Computer, Tide predictors, Torquetum and Water integrator. Digital Computers The digital computer is capable of performing operations on data represented in digital or number form i. e. data represented as a series of discrete elements arranged in a coded form. Digital computers are more accurate than analog computers. Digital computers handle values that are in discrete (binary 0’s and 1’s).

As the digital computers do not support mechanical based operations therefore they are freed from huge and heavy mechanical components like motors and gears so the size of these computers is smaller and are lighter than analog computers. The computers that we see all around us in offices, schools, homes and colleges are the examples of digital computers. Today’s digital computers contain special hardware as microprocessor, memory, input/output (I/O) devices and storage devices; and special softwares like Operating System (OS) and other utility softwares which make them more powerful and flexible. These computers are quieter than the analog computers for this they are ideal for office use.

The old digital computers include Zuse Z3 (May, 1941), Atanasoff-Berry Computer (1941), Colossus (1943), Harvard Mark I – IBM ASCC (1944) and ENIAC (1944). Today’s most commonly used digital computers are Pentium III (uses Pentium III microprocessor) and Pentium IV (uses Pentium IV microprocessor). These are very powerful systems and can support very wide variety of tasks. The speed of the microprocessors that these systems contain is measured in Gega Hertz (GHZ). Introduction to computers Hybrid Computers The term hybrid computer is frequently used to refer any computer system that comprises features of analog computers and digital computers. Hybrid computer has the properties of both analog and digital computers and can input and output analog and digital data.

The digital unit controls the analog unit by the means of instructions stored in the digital memory. A hybrid computer uses digital-toanalog and analog-to-digital conversion. These computers are widely used in the fields of robotics. These computers can process both discrete and continuous data. The examples of hybrid computer are HRS-100, a hybrid computer from Mihajlo Pupin Institute and WAT 1001 (a polish hybrid computer). Figure 1. 12 12 Figure 1. 12 – Polish WAT 1001 Classification of computers according to the purpose Special Purpose Computers Special purpose computers are the computers used to perform specific applications. They do not offer wide variety of tasks.

They are designed to perform a single or a limited set of tasks like the mainframe computers in the Airlines can only store the schedules of flights, information about the passengers etc. or a supercomputer used for predicting the weather or in a simulation of airplane. These computers are inflexible. These are commonly used in large industries and organizations but not in homes and offices. As they do not support wide variety of tasks they offer very high processing speed and power. General Purpose Computers General purpose computers can support wider variety of tasks like a home desktop computer can be used to print a document, play and edit music, play PC games, send an electronic mail (E-Mail), and much more which makes them very flexible. General purpose computers are ideal for home and office workplaces.

Introduction to computers Advantages of a Computer over a Human 13 1) Speed The computer can perform any type of calculation in a split of a second. Where as a human consumes some time first he will think of it that what sort of problem is it? What process should I apply to solve it? And also a human is not perfect at every time. This makes a human more time consumer than a computer. 2) Accuracy The computer is very much accurate to perform specific tasks unless any software or hardware failure or some technical problem occurs. The computer performs what it is told to do and work according to the given instructions and give a very accurate output.

Where as a human can make mistake and can apply a wrong process or method to solve a particular problem creating a bug in the result. 3) Delegacy The computers can perform a particular task infinite number of times repetitively if you have instructed the computer by creating a loop. The computer never becomes bore doing same task repetitively for several numbers of time where as a human can perform a certain task repetitively but after some period of time his mind will become bored by interacting with same sort of things every time. 4) Run for a long period of time The computer can perform a particular task infinite number of times as discussed earlier and by creating certain loop unless any power failure or hardware failure occurs.

Where as a human cannot perform a specific task continuously and need some rest after some moments. Introduction to computers 5) Multitasking 14 The computer can perform several different tasks a t a given moment at very high speed and with tremendous accuracy. Where as a human cannot concentrate his mind on multiple tasks like, a human cannot make a cup of tea while driving a car. Disadvantages of a Computer over a Human 1) Inflexibility The computers are designed to perform specific tasks like a computer can add two numbers or it can compare the two numbers but it cannot make a cup of tea for you. While a human is more flexible than a computer and can perform very wide variety of tasks than c computers. 2) Needs Detail

The computer can perform some processing on the inputted data but you have to input the data in very detail and you have to explain each and every thing into it. Suppose if you are giving the tasks to the computer to solve the equation 2 + 3 then you have to tell the computer what 2 and 3 are and also what + sign means. While a human can make sense to the equation and does not need detail every time. So it is truly said by someone that the humans are smarter than the computers. 3) Needs electric energy continuously To operate the computer the electric energy must be supplied to the computer continuously without any cuts. While a human also needs some sort of energy in the form of food but not every time. A human can store that energy and can work with stored energy. 4) Loss of data

The data store in a computer memory can be deleted or corrupted accidently or by the infection of nay damageable computer virus. This can cost you very much. But the human can store any type of memory permanently and cannot be lost by itself unless a natural disaster attacks the memory. Chapter 02 Parts of a Computer System Making surgery of the computer This chapter provides you the best information about various computer system components as, microprocessor, memory (RAM and ROM), storage, input and output devices. Author: Ali Asghar Manjotho 25/12/2005 Parts of a computer system 15 Parts of a Computer System Up to now we have seen that there are very large Figure 2. 1 computers that consume a whole big room or even a complete house.

These computers are used for specific purposes for solving specific complex problems like; super computer is used in weather forecasting that predicates the weather report or a large mainframe which is used in Air-lines to store the records of schedules of the flights, information about passengers’ passports and visas. And we have also seen that there are very small computers, which can be easily fitted in to your hand like PDAs and smart phone. So we come to Figure 2. 1 – Parts of a Computer System know that the computer size can vary dramatically but no matter how large or small a computer is, every computer is a part of system and a complete computer system consists of following four parts: Hardware Software Data and Information Operators (Users) Hardware

The mechanical components that make up the whole computer system are known as hardware or we can also define it as the parts of computer system that we can see and touch. All the components that we see like, monitor, keyboard, mouse, speakers, and the internal critical components of computer as RAM, ROM, processor, hard disk, CD-ROM, floppy drive and CMOS battery are known as the hardware. Every hardware component play an important role in making the computer run properly like, suppose the ROM (Read Only Memory) ? contains the instruction that make the computer start when ever turned on, if this component refuses to work than your computer will not remain a computer in itself as it will not start.

No matter how large or small the hardware component is, plays a leading role in any computer system like, a jumper (a miniature switch) is very small component but if misplaced and inserted in wrong pins then can damage your whole system. Parts of a computer system 16 Computer hardware is the physical part of a computer, including the digital circuitry, as distinguished from the computer software that executes within the hardware. The hardware of a computer is infrequently changed, in comparison with software and data, which are “soft” in the sense that they are readily created, modified or erased on the computer. Firmware is a special type of software that rarely, if ever, needs to be changed and so is stored on hardware devices such as read-only memory (ROM) where it is not readily changed (and is, therefore, “firm” rather than just “soft”).

There are two types of hardware devices Internal and External. The external devices are those which reside outside the system box’s casing like keyboard, mouse, monitor, speaker, microphone etc. The internal hardware devices are those which reside inside the system box like, hard disk, floppy drive, RAM, ROM, processor, modem etc. Also the devices like hard disks and modems can also be available in external models which are easily to carry around. Software Software is any set of instructions given by the user to the computer to work accordingly. Software can contain millions or billions of instructions that the computer uses to control its own hardware resources.

Without the software a computer is like a stylish Ferrari car without an engine. A computer cannot do any thing by itself unless a user instructs it and tells it what it has to do? A computer is just like a solider which every time waits for the instruction of a commander and cannot do any thing without his instructions. So you are as the commander of your computer system and can give any set of instructions to the computer to use it in the manner you want. Figure 2. 2 There are two types of softwares system software and application Figure 2. 2 – MS Office Word 2007 Software software. The system software helps the computer to control and manage its own hardware resources.

Where as an application software helps the users to make the computer to perform specific tasks like, creating an office document, listening music, sending an e-mail or chatting with friends via Internet. No matter what sort of instructions are they combine to develop a software. Parts of a computer system 17 Data and Information Data is the collection of individual facts and figure where as the processed data is called the information. Data is any thing that you are inputting in to the computer for processing. Data may also be called as raw information because we do not make much sense to it so we send it to the computer for processing to get the information.

To process any thing the computer requires some sort of data to make itself know what it has to do. Data can be in the form of set of instructions that tells the computer to work accordingly (namely operating system). Information, as defined above, is the processed data which completes our sense towards it. The information is only important to us, the users, not to the computer because we can not make much sense towards the data; however when the computer converts that data in the information we make the sense towards that processed data at a glance. It shows the importance of data to a computer and the information to a user. Suppose consider following pieces of data: Ali, 250, English, got, marks, only, in.

If these pieces of data are brought in front of any user he or she can not make much sense towards it but if the computer processes these pieces of data and converts it in to the information as below then you can make the sense towards it at glance as you are very much familiar with this sort of information. Ali got only 250 marks in English. This type of data is called information or processed data. Operators (Users) We, the people who operate and instruct the computer are called computer operators or users. The operator in any computer system is that much important as a driver is important to drive a car. We have already discussed that the computer is just like a solider who cannot do anything without the instructions or orders of his commander. Although today we have automatic computers which can perform any task any number of times with out any interaction of a user.

But here one thing should be cleared that no computer made till today is completely autonomous though it can perform specific tasks by itself but still you have to design the system, create the instructions for it, start it and repair it. A computer can be said totally autonomous if it can make its own instructions, it can be turned on and turned off by itself and it can repair its own broken components, which is almost impossible. So we come to know that no computer is totally autonomous therefore the computer will demand a user unless a new technology hits the rock. Parts of a computer system 18 The Data Processing Cycle As we do not make much sense to the data therefore the computer converts that raw data in to the useful information and the primary task of a computer is also to convert the raw data in to the information.

To do this task the computer performs a process called data processing cycle which is set of steps arranged in a particular manner. Each step of this process requires one or more components of the computer. Data processing cycle contains four steps: Input During this step the computer accepts the input from the user via any input device like keyboard or mouse. It is very important step as the computer cannot do any thing by itself so it needs the instructions in the form of input. Process During this step the processing devices (Processor) of the computer performs some processing on the inputted data according to the given set of instructions.

The data processed by the processor in stored in memory (RAM) temporarily so that the processor can receive and access the data very fast. So in this step the two important devices of the computer RAM and Processor are used. Output During this process the computer shows the result of processed data on some sort of output devices like monitor or printer. It is very important for the computer to show the output because if the computer cannot show the result then how can a person comes to know that what the computer has performed? Or what computer wants to say? Storage During this step the computer permanently stores the processed data on any storage device like hard disk.

It is important to save your important data on the permanently storage media so that you can access that data again when ever you want else you have to set the data again which will be itching and can be time consuming to write the data again and again. Parts of a computer system 19 Essential Computer Hardware The computer can contain several different types of components that your fingers are not enough to count them. Every component is responsible for performing a particular task like; the input devices are used for inputting the data and output devices shows the result. But every computer should contain following four essential components: Processor Memory Input and Output Devices Storage Devices Processor The processor is like the brain of a computer system. It is responsible for all the processing capabilities of a computer. It is usually referred as CPU (Central Processing Unit).

The computer converts the raw data into the useful information by applying some processing operations on the data and these processing operations are performed by this processor. Processor is a small chip on which million of transistors are integrated on to it. The processor is inserted in a special socket or slot on the motherboard. Today’s processors are also called microprocessors because they are very small and can be even smaller than a nail of a human thumb. The speed of the processor is measured in mega Figure 2. 3 – Microprocessor hertz (MHZ) or giga hertz (GHZ). These microprocessors are very fast and process the data in a split of a second.

The very first processor was 4-bit Intel 4004, released on November 15, 1971, developed by Federico Faggin and Marcian Hoff. Figure 2. 3 Parts of a computer system 20 Memory The term memory refers to the ability to remember. In term of computer the memory means the ability of a device to store the data temporarily or permanently. There are several types of memory in a personal computer but the two most important are RAM (Random Access Memory) and ROM (Read Only Memory). Both the memories are used for distinct purposes and have their own importance. Random Access Memory (RAM) Random access memory as its name implies the data can be read and written randomly.

It is volatile memory mean all the contents stored in this memory will be lost if the computer is turned off or power failure occur so it requires constant power supply and you should store the data stored in a RAM on any permanent storage media to avoid the data lost. As you can read the data to or write from RAM therefore the RAM is also known as read/write memory. It contains the data which is to be processed by the processor. When ever the processor required data for processing it checks the contents of the RAM. When ever you launch a program it is first stored in RAM so that it can perform fast. Figure 2. 4 Every personal computer contains at least one chip Figure 2. 4 – RAM (Random Access memory) of RAM. The RAM directly affects the performance of the whole ystem. It is common experience that more the RAM a computer contains faster it will operate. You can add more RAM by replacing or plugging more RAM chips on your motherboard. The amount of memory in a RAM is usually measured in megabytes (MB). The standard personal computer can contain 128 MB of RAM some other models can contain 256 MB of RAM. The newest personal computers can contain 512 or even 1 GB or 2 GB of RAM. Parts of a computer system 21 Read Only Memory (ROM) It is non-volatile memory means the contents of this memory can be retained even when the power is turned off. The data can only be read form this memory and cannot be written to it.

It is small chip like a RAM and a small battery called CMOS battery makes this chip alive even when the power is turned off. This chip contains the instructions which are used to start-up the computer. These instructions are also known as BIOS Utility. These instructions are executed every time when ever the computer is first started and check the status of each device connected to the computer whether it is in working condition or not. So as these instructions help to start-up the computer therefore these instructions should not be lost therefore these are stored in ROM so that these instruction remain even when the computer is turned off. Input and output devices

The input devices are used to enter the data into the computer to instruct it to work accordingly. The input devices are considered as the interface between the user and the computer. Through the input devices the users can communicate and instruct the computer. There are many types of input devices but the most commonly input devices used in a personal computer are keyboard and a mouse. The keyboard is used to enter the text and numbers, where as the mouse is used to enter the data which is used by the computer to set the cursor on the screen. There are also many other input devices which may include the variants of mouse like, track ball and track pad; Figure 2. 5 –

Input Devices it may include optical input devices like a digital pen also called a stylus; the devices that input still and moving pictures which includes the digital camera and web cam; the devices to control the movement of the character in a computer game like, joystick or joy pad; the sound inputting devices like a microphone and many many more. The output devices are used to display the result of processed data. The computer produces the result by accepting the data from user via input devices and by performing some processing operations on to it. Now this result is very much meaningful to the users and their must be a device at which this result could be displayed and this task is performed by the output devices. Figure 2. 5 Parts of a computer system 22

There are many types of output devices but the most commonly used output devices in a personal computer are the monitor and printer. The monitor shows the result temporarily by creating the soft copy while the printer shows the result permanently by creating the hard copy. There are also some other output devices like, plotter which is a special printing device, speakers which produces the sound output and many other devices. The input and output devices play an important role in any computer system environment. The computer would be useless without the input and output devices as there will be no means through which you can communicate with it and also computer would not display any sort of result to you. Storage Devices

The term storage devices refer to the devices which store the data permanently. The computer with processor, memory and input and output devices can perform well but to have a really functionable computing device you should have storage devices. The computer contains some memory (RAM) in it but it can store the data temporarily and can be lost when ever you turn off your PC. If you have a very important data that you do not want to loss at any cost and you are running with only temporary memory then what you will do? You will have to find the place where you can store that data permanently and only the storage devices can fulfill your this need.

There are two types of storage devices: Magnetic Storage Devices Optical Storage Devices Figure 2. 6 Magnetic Storage Devices The storage devices that use the magnetism to store the data are known as magnetic storage devices. These devices contain a flat round magnetic disk which rotates at very high speed. All the data is stored on this round disk. These magnetic disks are housed in a casing to protect them from dust particles and the casing which holds this magnetic disk is known as disk drive. These devices use a head known as read/write head which reads the data from and writes the data to the magnetic disk. Figure 2. 6 – Magnetic Storage Hard Disk Parts of a computer system 23

In some disk drive the magnetic disk is built directly in to the drive and is not supposed to be removed like the hard disk. Hard disk is considered as the primary storage area of a computer where you can store huge amount of your useful data. But some disk drives offer removable disks i. e. you can change and remove the older magnetic disk and insert a new fresh disk. Usually the floppy drives offer this feature. The floppy drives read the floppy diskettes which you can remove and change when ever you want. The advantage of hard disk over the floppy diskettes is that hard disk can store huge amount of data than a floppy and has a long life time where as the floppy diskettes become expired after some uses. Optical Storage Devices

The devices that use the optical lens and the laser technology to read the data from and write the data to an optical disc are known as optical storage devices. These devices emit the beam of lesser light on the optical disc and with the help of the reflected light it reads the data from the disc. These optical discs are known as compact discs (CDs) and are removable discs. This traditional CD can store 700 MB of data or 80 minutes of audio. Figure 2. 7 There are many types of optical storage devices like, CD-ROM, Figure 2. 7 – CD ROM CD-R, CD-RW, DVD-ROM, DVD-R, Combo drive. But the most commonly used is CD-Rom (Compact Disc-Read Only Memory). It is a rectangular plastic body contains a plastic tray which pops out and sucks the disc into to it and with Figure 2. the help of rotor it rotates the disc at very high speed and with the help of lesser it reads the data form the disc and send to the computer. CD-Rom drive can play only CDs and can not write the data onto it as it is read only device. The other types like CD-R (Compact Disc Recordable) drive and CDRW (Compact Disc Rewriteable) drive can write the data on the disc. CD-R drive can record the data to the disc only single time where as CD-RW drive can record and overwrite the data on the disc. The DVD (Digital Versatile Disk) is the newest development in the optical Figure 2. 8 – CD (Compact Disc) storage devices. A single DVD can hold 4. 7 GB to 17 GB of data and can store a full-length high quality movie using sophisticated compression technology.

The latest and the most popular optical device among the peoples is the Combo Drive, which is the combination of all the optical storage devices as discussed above. It can play CDs. Chapter 03 The Keyboard A tunnel to talk to computer This chapter gives you the brief introduction to the keyboard and its working principle. It also briefs you many different technologies and world wide different layout and designs of the keyboard. Author: Ali Asghar Manjotho 25/12/2005 Parts of a computer system 24 Keyboard Keyboard is primary input device it is used to input text, numbers and commands. It is just like a typewriter which works as a communicator between the user and the computer.

It is small plastic body containing matrix of several elastic keys arranged in certain groups. Keyboards can be categorized according to the shape, according to the size, according to the color, according to the number of keys they contain and so on. But the most commonly used keyboard is IBM Enhanced Keyboard designed by IBM, contains about 100 keys. These keys are arranged in to the five groups namely, Alphanumeric Keys Modifier Keys Numeric Keypad Function Keys Cursor-Movement Keys Figure 3. 1 Figure 3. 1 – Standard Keyboard Alphanumeric Keys The group of keys or the portion of the keyboard which looks like a typewriter containing alphabetic character ( i. e. A, B, C, X, Y, Z), special symbols (i. e. &, @, $, #), numbers (i. e. , 2, 3, 4, 5) and some special keys as (ENTER, SPACE, BACK SPACE, CAPS LOCK and TAB) keys is named as Alphanumeric Keys. The first line in this group is arranged as Q, W, E, R T, Y, this arrangement is called QWERTY arrangement and some times the keyboard containing this type of arrangement are known as QWERTY keyboards. It is very important group because it enables us to enter the English syntax like. The word processing softwares like Microsoft Word (MS Word) require a much deal with alphanumeric keys. This group of keys is the largest group containing about 54 number of keys. Modifier Keys The keys SHIFT, ALT, CTRL are known as modifier keys because they modify or change the functionality of other keys.

To modify the functionality of other key you have to press that key while holding down the modifier key. Like when you press J key it displays the small letter j on the screen but when pressed while holding down SHIFT key it will display capital J on the screen. Similarly F4 key Parts of a computer system 25 has its own function but when pressed while holding down ALT key it closes any opened active window. The modifier keys have played very important role in shrinking the size of the keyboard as if there were no modifier keys present in the keyboard then you had separate keys for capital and small letter and for some special functions so the modifier keys have helped very much to overcome this complex problem.

Numeric Keypad It is just like a calculator located usually at the right side of the keyboard. It contains numbers form 0 to 9, arithmetic operator (+, -, *, & /), an enter key and a num lock key. It is used for fast calculation as it provides separate calculator based design. It is widely used in the fields where people perform a lot of calculations, creating data spread sheets and in accountings. The num lock key also plays an important role in this group, when the num lock key is activated this group behaves as a calculator while when deactivated it performs cursor-movement keys’ functions. Functi

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