Upcoming SlideShare
×

# introduction to it

2,820 views
2,664 views

Published on

Published in: Education, Technology
0 Likes
Statistics
Notes
• Full Name
Comment goes here.

Are you sure you want to Yes No
• Be the first to comment

• Be the first to like this

Views
Total views
2,820
On SlideShare
0
From Embeds
0
Number of Embeds
1
Actions
Shares
0
42
0
Likes
0
Embeds 0
No embeds

No notes for slide

### introduction to it

1. 1. INTRODUCTION TO COMPUTERS Let us begin with the word ‘compute’. It means ‘to calculate’. We all are familiar with calculations in our day to day life. We apply mathematical operations like addition, subtraction, multiplication, etc. and many other formulas for calculations. Simpler calculations take less time. But complex calculations take much longer time. Another factor is accuracy in calculations. So man explored with the idea to develop a machine which can perform this type of arithmetic calculation faster and with full accuracy. This gave birth to a device or machine called ‘computer’. The computer we see today is quite different from the one made in the beginning. The number of applications of a computer has increased, the speed and accuracy of calculation has increased. You must appreciate the impact of computers in our day to day life. Reservation of tickets in Air Lines and Railways, payment of telephone and electricity bills, deposits and withdrawals of money from banks, business data processing, medical diagnosis, weather forecasting, etc. are some of the areas where computer has become extremely useful. However, there is one limitation of the computer. Human beings do calculations on their own. But computer is a dumb machine and it has to be given proper instructions to carry out its calculation. This is why we should know how a computer works. Computer is an electronic device. As mentioned in the introduction it can do arithmetic calculations faster. But as you will see later it does much more than that. It can be compared to a magic box, which serves different purpose to different people. For a common man computer is simply a calculator, which works automatic and quite fast. For a person who knows much about it, computer is a machine capable of solving problems and manipulating data. It accepts data, processes the data by doing some mathematical and logical operations and gives us the desired output. Therefore, we may define computer as a device that transforms data. Data can be anything like marks obtained by you in various subjects. It can also be name, age, sex, weight, height, etc. of all the students in your class or income, savings, investments, etc., of a country. What is Computer? In basic terms computer is an electronic device that processes data, converting it into information that is useful to people:-1. Electronic device ((Electronics is the branch of science and technology which makes use of the controlled motion of electrons through different media and vacuum. The ability to control electron flow is usually applied to information handling or device control).2. Process data3. Converting data into information 1|Page
2. 2. INTRODUCTION TO COMPUTERSAny computer regardless of its type is controlled by programmed instructions which give the machine apurpose and tell it what to do.Computer is an advanced electronic device that takes raw data as input from the user andProcesses these data under the control of set of instructions (called program) and givesThe result (output) and saves output for the future use. It can process both numerical andNon-numerical (arithmetic and logical) calculations.A computer is an electronic device, which is used to accept, store, retrieve and process the data. It iscalled as data processor because it is mainly used for processing data for producing meaningfulinformation.A. ACCEPTS DATA INPUTB. PROCESSES DATA PROCESSINGC. PRODUCES OUTPUT OUTPUTD. STORES RESULTS STORAGEINPUTInput is the raw information entered into a computer from the input devices. It is thecollection of letters, numbers, images etc.Process:Process is the operation of data as per given instruction. It is totally internal process ofthe computer system.Output:Output is the processed data given by computer after data processing. Output is alsocalled as Result. We can save these results in the storage devices for the future use.Computer SystemAll of the components of a computer system can be summarized with the simpleequations.COMPUTER SYSTEM = HARDWARE + SOFTWARE+ USERHardware = Internal Devices + Peripheral DevicesAll physical parts of the computer (or everything that we can touch) are known asHardware. Software = Programs Software gives "intelligence" to the computer. USER = Person, who operates computer 2|Page
3. 3. INTRODUCTION TO COMPUTERSHISTORY OF COMPUTERHistory of computer could be traced back to the effort of man to count large numbers. This process ofcounting of large numbers generated various systems of numeration like Babylonian system ofnumeration, Greek system of numeration, Roman system of numeration and Indian system ofnumeration. Out of these the Indian system of numeration has been accepted universally. It is the basis ofmodern decimal system of numeration (0, 1, 2, 3, 4, 5, 6, 7, 8, 9). Later you will know how the computersolves all calculations based on decimal system. But you will be surprised to know that the computer doesnot understand the decimal system and uses binary system of numeration for processing.We will briefly discuss some of the path-breaking inventions in the field of computing devicesCalculating MachinesIt took over generations for early man to build mechanical devices for counting large numbers. The firstcalculating device called ABACUS was developed by the Egyptian and Chinese people.The word ABACUS means calculating board. It consisted of sticks in horizontal positions on which wereinserted sets of pebbles. A modern form of ABACUS is given in Fig. 1.2. It has a number of horizontal barseach having ten beads. Horizontal bars represent units, tens, hundreds, etcAbacus ComputerNapier’s bonesEnglish mathematician John Napier built a mechanical device for the purpose of multiplication in 1617 AD. The device was known as Napier’s bones.Slide RuleEnglish mathematician Edmund Gunter developed the slide rule. This machine could perform operationslike addition, subtraction, multiplication, and division. It was widely used in Europe in 16th century.Pascals Adding and Subtractory MachineYou might have heard the name of Blaise Pascal. He developed a machine at the age of 19 that could addand subtract. The machine consisted of wheels, gears and cylinders.Leibniz’s Multiplication and Dividing MachineThe German philosopher and mathematician Gottfried Leibniz built around 1673 a mechanical device thatcould both multiply and divide. 3|Page
4. 4. INTRODUCTION TO COMPUTERS Babbage’s Analytical Engine It was in the year 1823 that a famous English man Charles Babbage built a mechanical machine to do complex mathematical calculations. It was called difference engine. Later he developed a general-purpose calculating machine called analytical engine. You should know that Charles Babbage is called the father of computer.Mechanical and Electrical CalculatorIn the beginning of 19th century the mechanical calculator was developed to perform all sorts of mathematicalcalculations. Up to the 1960s it was widely used. Later the rotating part of mechanical calculator was replaced by electricmotor. So it was called the electrical calculator.Modern Electronic CalculatorThe electronic calculator used in 1960 s was run with electron tubes, which was quite bulky. Later it was replaced withtransistors and as a result the size of calculators became too small.The modern electronic calculator can compute all kinds of mathematical computations and mathematical functions. It canalso be used to store some data permanently. Some calculators have in-built programs to perform some complicatedcalculations. . 4|Page
5. 5. INTRODUCTION TO COMPUTERSCOMPUTER GENERATIONSYou know that the evolution of computer started from 16th century and resulted in the form that we see today. Thepresent day computer, however, has also undergone rapid change during the last fifty years. This period, duringwhich the evolution of computer took place, can be divided into five distinct phases known as Generations ofComputers.Each phase is distinguished from others on the basis of the type of switching circuits used.1.6.1 First Generation Computers(1940-1956: Vacuum Tubes)The first computers used vacuum tubes for circuitry and magnetic drums for memory, and were often enormous,taking up entire rooms. These computers were large in size and writing programs on themwas difficult. Firstgeneration computers relied on machine language to perform operations, and they could only solve one problem ata time. Machine languages are the only languages understood by computers. While easily understood by computers,machine languages are almost impossible for humans to use because they consist entirely of numbers. ComputerProgrammers, therefore, use either high level programming languages or an assembly language programming. Anassembly language contains the same instructions as a machine language, but the instructions and variables havenames instead of being just numbersENIAC: It was the first electronic computer built in 1946 at University of Pennsylvania, USA by John Eckert andJohnMauchy. It was named Electronic Numerical Integrator and Calculator (ENIAC). The ENIAC was 30 50 feet long,weighed 30 tons, contained 18,000 vacuum tubes, 70,000 registers, 10,000 capacitors and required 150,000 watts ofelectricity. Today your favorite computer is many times as powerful as ENIAC, still size is very small.EDVAC: It stands for Electronic Discrete Variable Automatic Computer and was developed in 1950. The concept ofstoring data and instructions inside the computer was introduced here. This allowed much faster operation since thecomputer had rapid access to both data and instructions. The other advantages of storing instruction was thatcomputer could do logical decision internally.Other Important Computers of First GenerationEDSAC: It stands for Electronic Delay Storage Automatic Computer and was developed by M.V. Wilkes at CambridgeUniversity in 1949.UNIVAC-1: Ecker and Mauchly produced it in 1951 by Universal Accounting Computer setup.Limitations of First Generation ComputerFollowings are the major drawbacks of First generation computers.1. The operating speed was quite slow.2. Power consumption was very high.3. It required large space for installation.4. The programming capability was quite low5|Page
6. 6. INTRODUCTION TO COMPUTERSSecond Generation Computers 1956-1963: TransistorsAround 1955 a device called Transistor replaced the bulky electric tubes in the first generationcomputer. Transistorsare smaller than electric tubes and have higher operating speed. They have nofilament (conductor which easily gets heat up ) and require no heating. Manufacturing cost wasalso very low. Thus the size of the computer got reduced considerably. The transistor was farsuperior to the vacuum tube,allowing computers to become smaller, faster, cheaper,more energy-efficient and more reliable than their first-generation predecessors. Though the transistor stillgenerated a great deal of heat that subjected the computer to damage, it was a vast improvementover the vacuum tube Todays latest microprocessor contains tens of millions of microscopictransistors.It is in the second generation that the concept of Central Processing Unit (CPU), memory,programming language and input and output units were developed. The programming languagessuch as COBOL, FORTRAN were developedduring this period. Some of the computers of the SecondGeneration wereIBM 1620: Its size was smaller as compared to First Generation computers and mostly used forscientificpurpose.IBM 1401: Its size was small to medium and used for business applications.CDC 3600: Its size was large and is used for scientific purposes.Third Generation ComputersThe third generation computers were introduced in 1964. They used Integrated Circuits (ICs). TheseICs are popularly known as Chips. The development of the integrated circuit was the hallmark of thethird generation of computers. Transistors were miniaturized and placed on silicon chips, calledsemiconductors, which drastically increased the speed and efficiency of computers.A single IC has many transistors, registers and capacitors built on a single thin slice of silicon. So it isquite obvious that the size of the computer got further reduced. A chip is a small piece of semiconducting material(usually silicon) on which an integrated circuit is embedded. A typical chip is lessthan ¼-square inches and can contain millions of electronic components(transistors). Computersconsist of many chips placed on electronic boards called printed circuit boards. There are differenttypes of chips. For example, CPU chips (also called microprocessors) contain an entire processingunit, whereas memory chips contain blank memory.users interacted with third generation computers through keyboards and monitors and interfacedwith an operating system, which allowed the device to run many different applications at one timewith a central program that monitored the memory. Computers for the first time became accessibleto a mass audience because they were smaller and cheaper than their predecessorsSome of the computers developed during this period were IBM-360, ICL-1900, IBM-370, and VAX-750. Higher level language such as BASIC (Beginners All purpose Symbolic Instruction Code) wasdeveloped during this period.Computers of this generations were small in size, low cost, large memory and processing speed isvery high.6|Page
7. 7. INTRODUCTION TO COMPUTERSFourth Generation Computers 1971-PresentThe present day computers that you see today are the fourth generation computers that startedaround 1975. It uses large scale Integrated Circuits (LSIC) built on a single silicon chip calledmicroprocessors. A silicon chip that contains a CPU. In the world of personal computers,the termsmicroprocessor and CPU are used interchangeably. At the heart of all personal computers and mostworkstations sits a microprocessor. Microprocessors also control the logic of almost all digitaldevices .Three basic characteristics differentiate microprocessors:Instruction Set: The set of instructions that the microprocessor can execute.Bandwidth: The number of bits processed in a single instruction.Clock Speed: Given in megahertz (MHz), the clock speed determines how many instructions persecond the processor can execute.Abbreviation of central processing unit, and pronounced as separate letters. The CPU is the brains ofthe computer. Sometimes referred to simply as the processor or central processor, the CPU is wheremost calculations take place. In terms of computing power,the CPU is the most important elementof a computer system.Two typical components of a CPU are:The arithmetic logic unit (ALU), which performs arithmetic and logical operations.The control unit, which extracts instructions from memory and decodes and executes them, callingon the ALU when necessary.In 1981 IBM introduced its first computer for the home user, and in 1984 Apple introduced theMacintosh. Microprocessors also moved out of the realm of desktop computers and into manyareas of life as more and more everyday products began to use microprocessors.As these small computers became more powerful, they could be linked together to form networks,which eventually led to the development of the Internet. Fourth generation computers also saw thedevelopment of GUIs, the mouse and handheld devices Due to the development of microprocessor it is possible to place computer’s central processing unit(CPU) on single chip. These computers are called microcomputers. Later very large scale IntegratedCircuits (VLSIC) replaced LSICs.Thus the computer which was occupying a very large room in earlier days can now be placed on atable. The personal computer (PC) that you see in your school is a Fourth Generation Computer.7|Page
8. 8. INTRODUCTION TO COMPUTERSFifth Generation - Present and Beyond: Artificial IntelligenceFifth generation computing devices, based on artificial intelligence, are still in development,thoughthere are some applications, such as voice recognition, that are being used today.Artificial Intelligence is the branch of computer science concerned with making computers behavelike humans. The term was coined in 1956 by John McCarthy at the Massachusetts Institute ofTechnology. Artificial intelligence includes:Games Playing: programming computers to play games such as chess and checkersExpert Systems: programming computers to make decisions in real-life situations (for example,some expert systems help doctors diagnose diseases based on symptoms)Natural Language: programming computers to understand natural human languagesNeural Networks: Systems that simulate intelligence by attempting to reproduce the types ofphysical connections that occur in animal brainsRobotics: programming computers to see and hear and react to other sensory stimuliCurrently, no computers exhibit full artificial intelligence (that is, are able to simulate humanbehavior). The greatest advances have occurred in the field of games playing. The best computerchess programs are now capable of beating humans. In May,1997, an IBM super-computer calledDeep Blue defeated world chess champion Gary Kasparov in a chess match.In the area of robotics, computers are now widely used in assembly plants, but they are capableonly of very limited tasks. Robots have great difficulty identifying objects based on appearance orfeel, and they still move and handle objects clumsily.Natural-language processing offers the greatest potential rewards because it would allow people tointeract with computers without needing any specialized knowledge. You could simply walk up to acomputer and talk to it. Unfortunately, programming computers to understand natural languageshas proved to be more difficult than originally thought. Some rudimentary translation systems thattranslate from one human language to another are in existence, but they are not nearly as good ashuman translators.There are also voice recognition systems that can convert spoken sounds into written words, butthey do not understand what they are writing; they simply take dictation. Even these systems arequite limited -- you must speak slowly and distinctly.In the early 1980s, expert systems were believed to represent the future of artificial intelligence andof computers in general. To date, however, they have not lived up to expectations. Many expertsystems help human experts in such fields as medicine and engineering, but they are very expensiveto produce and are helpful only in special situations.Today, the hottest area of artificial intelligence is neural networks, which are proving successful inan umber of disciplines such as voice recognition and natural-language processing.There are several programming languages that are known as AI languages because they are usedalmost exclusively for AI applications. The two most common are LISP and Prolog8|Page
9. 9. INTRODUCTION TO COMPUTERSD.A World of Computers Computers are everywhere: at work, at school, and at home (Figure 1-1). Mobile devices, such asmany cell phones, often are classified as computers. Computers are a primary means of local and global communication for billions of people. Employees correspond with clients, students with classmates and teachers, and family with friends and other family members. Through computers, society has instant access to information from around the globe. Local And national news, weather reports, sports scores, airline schedules, telephone directories, mapsand directions, job listings, credit reports, and countless forms of educational material always areaccessible. From the computer, you can make a telephone call, meet new friends, share photos andvideos, share opinions, shop, book flights, file taxes, take a course, receive alerts, and automate yourhome. In the workplace, employees use computers to create correspondence such as e-mail messages,memos, and letters; manage calendars; calculate payroll; track inventory; and generate invoices.At school, teachers use computers to assist with classroom instruction. Students use computers tocomplete assignments and research. Instead of attending class on campus, some students take entireclasses directly from their computer. People also spend hours of leisure time using a computer. They play games, listen to music or radio broadcasts, watch or compose videos and movies, read books and magazines, share stories,research genealogy, retouch photos, and plan vacations. Many people believe that computer literacy is vital to success. Computer literacy, also known asdigital literacy, involves having a current knowledge and understanding of computers and their uses.Because the requirements that determine computer literacy change as technology changes, you mustkeep up with these changes to remain computer literate.Data and InformationComputers process data into information. Data is a collection of unprocessed items, which canincludetext, numbers, images, audio, and video. Information conveys meaning and is useful to people.As shownin Figure 1-2, for example, computers process several data items to print information inthe form of a cashregister receipt. 9|Page
10. 10. INTRODUCTION TO COMPUTERSFigure 1-2 A computer processes data into information. In this simplified example, the item ordered, itemprice,quantity ordered, and amount received all represent data. The computer processes the data toproduce the cash register receipt (information).Information Processing CycleComputers process data (input) into information (output). Computers carry out processes usinginstructions, which are the steps that tell the computer how to perform a particular task. A collectionof related instructions organized for a common purpose is referred to as software. A computeroften holds data, information, and instructions in storage for future use. Some people referto the series of input, process, output, and storage activities as the information processing cycle.Recently, communications also has become an essential element of the information processing cycle.The Components of a ComputerA computer contains many electric, electronic, and mechanical components known as hardware.These components include input devices, output devices, a system unit, storage devices, andcommunications devices. Figure 1-3 shows some common computer hardware components.Input DevicesAn input device is any hardware component that allows you to enter data and instructions intoa computer. Five widely used input devices are the keyboard, mouse, microphone, scanner, and Webcam (Figure 1-3).A computer keyboard contains keys you press to enter data into the computer. A mouse is a smallhandheld device. With the mouse, you control movement of a small symbol on the screen, calledthe pointer, and you make selections from the screen.A microphone allows a user to speak into the computer. A scanner converts printed material (suchas text and pictures) into a form the computer can use.A Web cam is a digital video camera that allows users to create movies or take pictures and storethem on the computer instead of on tape or film. 10 | P a g e
11. 11. INTRODUCTION TO COMPUTERSOutput DevicesAn output device is any hardware compo nent that conveys information to one or more people.Three commonly used output devices are a printer, a monitor, and speakers (Figure 1-3).A printer produces text and graphics on a physical medium such as paper. A monitor displays text,graphics, and videos on a screen. Speakers allow you to hear music, voice, and other audio (sounds).Figure 1-3 Common computer hardware components include the keyboard, mouse, microphone, scanner,Web cam, printer,monitor, speakers, system unit, hard disk drive, external hard disk, optical disc drive(s), USB flash drive,card reader/writer, memorycards, and modem.Figure 1-3 Common computer hardware components include the keyboard, mouse,microphone, scanner, Web cam, printer,monitor, speakers, system unit, hard disk drive, external hard disk, optical disc drive(s), USB flash drive,card reader/writer, memorycards, and modem. 11 | P a g e
12. 12. INTRODUCTION TO COMPUTERSFigure 1-3 Common computer hardware components include the keyboard, mouse, microphone, scanner,Web cam, printer,monitor, speakers, system unit, hard disk drive, external hard disk, optical disc drive(s), USB flash drive,card reader/writer, memorycards, and modem.System UnitThe system unit is a case that contains electronic components of the computer that are used toprocess data (Figure 1-3 on the previous page). The circuitry of the system unit usually is part of oris connected to a circuit board called the motherboard.Two main components on the motherboard are the processor and memory. The processor, alsocalled the CPU (central processing unit), is the electronic component that interprets and carriesout the basic instructions that operate the computer. Memory consists of electronic components that 12 | P a g e
13. 13. INTRODUCTION TO COMPUTERSstore instructions waiting to be executed and data needed by those instructions. Most memory keepsdata and instructions temporarily, which means its contents are erased when the computer is shut off.Storage DevicesStorage holds data, instructions, and information for future use. For example, computers can storehundredsor millions of customer names and addresses. Storage holds these items permanently.A computer keeps data, instructions, and information on storage media. Examples of storagemedia are USB flash drives, hard disks, optical discs, and memory cards. A storage device records(writes) and/or retrieves (reads) items to and from storage media. Storage devices often function as asource of input because they transfer items from storage to memory.A USB flash drive is a portable storage device that is small and lightweight enough to be transportedon a keychain or in a pocket (Figure 1-3). The average USB flash drive can hold about 4billion characters.A hard disk provides much greater storage capacity than a USB flash drive. The average hard diskcan hold more than 320 billion characters. Hard disks are enclosed in an airtight, sealed case. Althoughsome are portable, most are housed inside the system unit (Figure 1-4). Portable hard disks are eitherexternal or removable. An external hard disk is a separate, freestanding unit, whereas you insert andremove a removable hard disk from the computer or a device connected to the computer.An optical disc is a flat, round, portable metal disc with a plastic coating. CDs, DVDs, and Blu-rayDiscs are three types of optical discs. A CD can hold from 650 million to 1 billion characters. SomeDVDs can store two full-length movies or 17 billion characters (Figure 1-5). Blu-ray Discs can storeabout 46 hours of standard video, or 100 billion characters.Some mobile devices, such as digital cameras, use memory cards as the storage media. You canuse a card reader/writer (Figure 1-3) to transfer stored items, such as digital photos, from thememory card to a computer or printer. 13 | P a g e
14. 14. INTRODUCTION TO COMPUTERS Communications Devices A communications device is a hardware component that enables a computer to send (transmit) and receive data, instructions, and information to and from one or more com putersor mobile devices. A widely used communications device is a modem (Figure 1-3). Communications occur over cables, telephone lines, cellular radio networks, satellites, and other transmission media. Some transmission media, such as satellites and cellular radio networks, are wireless, which means they have no physical lines or wires. CHARACTERISTICS OF COMPUTER Let us identify the major characteristics of computer. These can be discussed under the headings of speed, accuracy, diligence, versatility and memory. Now-a-days computer is playing a main role in everyday life it has become the need of people just like television, telephone or other electronic devices at home. It solves the human problems very quickly as well as accuratly. The important characteristics of a computer are described below:1. Speed The computer is a very high speed electronic device. The operations on the data inside the computer are performed through electronic circuits according to the given instructions. The data and instructions flow along these circuits with high speed that is close to the speed of light. Computer can perform million of billion of operations on the data in one second. The computer generates signals during the operation process therefore the speed of computer is usually measure in mega hertz (MHz) or gega hertz (GHz). It means million cycles units of frequency is hertz per second. Different computers have different speed.The computer was invented as a high-speed calculator. This has led to many scientific projects which were previously impossible. The control of the moon landing would not have been feasible without computers, and neither would todays more scientific approach to weather prediction. If we want tomorrows forecast today (and not in six months time) meteorologists can use the computer to perform quickly the necessary calculations and analyses. When making flight reservations we want to know well in advance of take-off that a seat will be available - if it is not, then we have time to make other arrangements. The ability to get answers fast enough so that one has time to take action on them (or to make alternative plans, as in the case of airline reservations) makes real-time computing possible.Electrical pulses travel at 14 | P a g e
15. 15. INTRODUCTION TO COMPUTERSincredible speeds and, because the computer is electronic, its internal speed is virtually instantaneous.We do not talk in terms of seconds or even milliseconds. Our units of speed are the microsecond(millionths), the nanosecond (thousand0millionths) and latterly even the picosecond (million-millionths).A powerful computer is capable of adding together two 18-digit number in 300 to 400 nanoseconds.Consider two examples from non-numerical environments. The manual indexing of the complete works ofThomas Aquinas (approximately 13 million words) would have taken 50 scholars about 40 years toaccomplish. With the aid of a computer a few scholars did it in less than one year. Fingerprintidentification, in time to catch a criminal before he flees the country, would be impossible withoutcomputers. The first example enables us to enjoy knowledge that would otherwise be unobtainablewithin our own lifetime. In the second example, the police gain time in which to act.2. Arithmetical and Logical OperationsA computer can perform arithmetical and logical operations. In arithmetic operations, it performs theaddition, subtraction, multiplication and division on the numeric data. In logical operation it compares thenumerical data as well as alphabetical data.3. AccuracyIn addition to being very fast, computer is also very accurate device. it gives accurate output resultprovided that the correct input data and set of instructions are given to the computer. It means thatoutput is totally depended on the given instructions and input data. If input data is in-correct then theresulting output will be in-correct. In computer terminology it is known as garbage-in garbage-out.4. ReliabilityThe electronic components in modern computer have very low failure rate. The modern computer canperform very complicated calculations without creating any problem and produces consistent (reliable)results. In general, computers are very reliable. Many personal computers have never needed a servicecall. Communications are also very reliable and generally available whenever needed.5. StorageA computer has internal storage (memory) as well as external or secondary storage. In secondary storage,a large amount of data and programs (set of instructions) can be stored for future use. The stored dataand programs are available any time for processing. Similarly information downloaded from the internetcan be saved on the storage media.6. Retrieving data and programsThe data and program stored on the storage media can be retrieved very quickly for further processing. Itis also very important feature of a computer.7. AutomationA computer can automatically perform operations without interfering the user during the operations. Itcontrols automatically different devices attached with the computer. It executes automatically theprogram instructions one by one.A computer is much more than an adding machine, calculator or check-out till, all of which require humanoperators to press the necessary keys for the operations to be performed. Once a program is in thecomputers memory, the individual instructions are then transferred, one after the other, to the control 15 | P a g e
16. 16. INTRODUCTION TO COMPUTERSunit for execution. The CPU follows these instructions until it meets a last instruction which says stopprogram execution. When Babbage claimed that his Analytical Engine would be automatic, he meant thatonce the process had begun, it would continue without the need for human intervention untilcompletion.8. VersatilityVersatile means flexible. Modern computer can perform different kind of tasks one by one ofsimultaneously. It is the most important feature of computer. At one moment your are playing game oncomputer, the next moment you are composing and sending emails etc. In colleges and universitiescomputers are use to deliver lectures to the students. The talent of computer is dependent on thesoftware. Computers seem capable of performing almost any task, provided that the task can be reducedto series of logical steps. For example, a task such as preparing a payroll or controlling the flow of trafficcan be broken down into a logical sequence of operations, whereas comparing the tones of a turner witha Vermeer cannot. Yet the computer itself has only limited ability and, in the final analysis, actuallyperforms only four basic operations: It exchanges information with the outside world via I/O devices, Ittransfers data internally within the CUP, It performs the basic arithmetical operations, It performsoperations of comparison. IN one sense, then, the computer is not versatile because it is limited to fourbasic functions. Yet, because so many daily activities can be reduced to interplay between thesefunctions, it appears that computers are highly ingenious. Programming is the craft or reducing a givenproblem into interplay between these few operations.9. CommunicationsToday computer is mostly used to exchange messages or data through computer networks all over theworld. For example the information can be received or send through the internet with the help ofcomputer. It is most important feature of the modern information technology.10. DiligenceA computer can continually work for hours without creating any error. It does not get tired while workingafter hours of work it performs the operations with the same accuracy as well as speed as the first one.Being a machine, a computer does not suffer from the human traits of tiredness and lack ofconcentration. If 3 million calculations have to be performed, it will perform the 3 millionth with exactlythe same accuracy and speed as the first. This factory may cause those whose jobs are highly repetitive toregard the computer as a threat. But to those who rely on a continuous standard of output, e.g., qualitycontrol in the refining of oil and other chemical processes, the computer will be seen as a considerablehelp.The Basic Anatomy of the ComputerIt receives information (input); it processes this information in some way according to set of preciseinstructions (in the CPU); and it then presents the results in a useful form (output).On closer inspectionwe find that the CPU (the computer itself, remember) has to store the information in a memory before itcan carry out processing operations. Two kinds of information have to be input, the program and thedata. The program is the set of instructions which the computer is to carry out, and the data is theinformation on which these instructions are to operate. For example, if the task is to sort a list oftelephone subscribers into alphabetical orders, the sequence of instructions or procedure which guidesthe computer through this operation is the program, whilst the list of names to be sorted is the data. IN 16 | P a g e
17. 17. INTRODUCTION TO COMPUTERSthe Analytical Engine calculations were to be handled by an arithmetic unit which Babbage called the Mill.The computer also has an arithmetic unit. Arithmetic, because all computer operations involve themanipulation of numbers. All information, program and data, are represented in numeric form. Themanipulations also include making comparisons and logic type operations as well as arithmetic operations( + - * / ), and for this reason the unit is referred to in full as the arithmetic and Logic Unit (ALU).TheElectronic Discrete Variable Automatic Computer (EDVAC) in 1952, was to be one such computer. Thememory unit stored both the instructions and data to be used for the calculations. IN 1946, Ekert andMauchly formed their own company, which in 1949 was incorporated as the UNIVAC division of theRemington Rand Company Ltd., In 1951 the UNIVAC I, i.e. the computer developed by Ekert and Mauchlybecame operational at the Census Bureau. This computer was self-checking and used magnetic tape fordata input and output. The UNIVAC I was run 24 hours a day until 1963. Yet, another UNIVAC I was put tobusiness by the General Electric Corporation in 1954.The first generation of computers was marked by theuse of vacuum tubes as the electronic components and by the use of either electrostatic tubes or mercurydelay lines for storage. Power tapes and punched cards were also used. Electronic time per operationranged from 0.1 millisecond, while memory access time was 1 millisecond.11. No11. FeelingsComputer is an electronic machine. It has no feelings. It detects objects on the basis of instructions givento it. Based on our feelings, taste, knowledge and experience: we can make certain decisions andjudgments in our daily life. On the other hand, computer cannot make such judgments on their own. Theirjudgments are totally based on instructions given to them.12. ConsistencyPeople often have difficulty to repeat their instructions again and again. For example, a lecturer feelsdifficulty to repeat a same lecture in a class room again and again. Computer can repeat actionsconsistently (again and again) without losing its concentration:To run a spell checker (built into a word processor) for checking spellings in a document.To play multimedia animations for training purposes.To deliver a lecture through computer in a class room etc.A computer will carry out the activity with the same way every time. You can listen a lecture or performany action again and again.13. PrecisionComputers are not only fast and consistent but they also perform operations very accurately andprecisely. For example, in manual calculations and rounding fractional values (That is value with decimalpoint can change the actual result). In computer however, you can keep the accuracy and precision up tothe level, you desire. The length calculations remain always accurate.14. Cheaper (Reduction of cost) Computers are short term investment in order to achieve a long termgain. Though the investment is high they reduce the cost of each and every transaction. They reduce manpower and leads to an elegant and efficient way for computing various tasks. Storehouse (Memory) 17 | P a g e
18. 18. INTRODUCTION TO COMPUTERSSecondary storage devices are the key for the data storage. They store the data for which the user wantsto retrieve these data for future use. The examples for various secondary devices are Floppy disk, Opticaldisks (CS and DVD), Zip drives, Thumb drives etc. The data of smaller size can be easily fetched and theycan be copied to the primary memory (RAM).Example: Data Warehousing made by IBM.15. StageThe speed with which computers can process large quantities of information has led to the generation ofnew information on a vast scale, in other words, the computer has compounded the informationexplosion. How can people cope with it? We cant, but computers can. But where do they keep it all? ASa human acquires new knowledge, the brain subconsciously selects what it feels to be important andworth retaining in its memory, and relegates unimportant details to the back of the mind or just forgetsthem. In computers, the internal memory of the CPU is only large enough to retain a certain amount ofinformation. It is therefore, impossible to store inside the computer the records, for example, of everyPremium Bond and the names and address of their owners. All of this data is stored outside of thememory of the CPU, on auxiliary or secondary storage devices. Small sections of the total data can beaccessed very quickly by the CPU and brought into the main, internal memory, as and when required forprocessing.Advantages and Disadvantages of Using ComputersCHARACTERISTICS OF COMPUTERLet us identify the major characteristics of computer. These can be discussed under the headings ofspeed, accuracy,diligence, versatility and memory.Now-a-days computer is playing a main role in everyday life it has become the need of people just liketelevision, telephone or other electronic devices at home. It solves the human problems very quickly aswell as accuratly. The important characteristics of a computer are described below:1. SpeedThe computer is a very high speed electronic device. The operations on the data inside the computer areperformed through electronic circuits according to the given instructions. The data and instructions flowalong these circuits with high speed that is close to the speed of light. Computer can perform million ofbillion of operations on the data in one second. The computer generates signals during the operationprocess therefore the speed of computer is usually measure in mega hertz (MHz) or gega hertz (GHz). Itmeans million cycles units of frequency is hertz per second. Different computers have different speed.2. Arithmetical and Logical OperationsA computer can perform arithmetical and logical operations. In arithmetic operations, it performs theaddition, subtraction, multiplication and division on the numeric data. In logical operation it compares thenumerical data as well as alphabetical data.3. AccuracyIn addition to being very fast, computer is also very accurate device. it gives accurate output result 18 | P a g e
19. 19. INTRODUCTION TO COMPUTERSprovided that the correct input data and set of instructions are given to the computer. It means thatoutput is totally depended on the given instructions and input data. If input data is in-correct then theresulting output will be in-correct. In computer terminology it is known as garbage-in garbage-out.4. ReliabilityThe electronic components in modern computer have very low failure rate. The modern computer canperform very complicated calculations without creating any problem and produces consistent (reliable)results. In general, computers are very reliable. Many personal computers have never needed a servicecall. Communications are also very reliable and generally available whenever needed.5. StorageA computer has internal storage (memory) as well as external or secondary storage. In secondary storage,a large amount of data and programs (set of instructions) can be stored for future use. The stored dataand programs are available any time for processing. Similarly information downloaded from the internetcan be saved on the storage media.6. Retrieving data and programsThe data and program stored on the storage media can be retrieved very quickly for further processing. Itis also very important feature of a computer.7. AutomationA computer can automatically perform operations without interfering the user during the operations. Itcontrols automatically different devices attached with the computer. It executes automatically theprogram instructions one by one.8. VersatilityVersatile means flexible. Modern computer can perform different kind of tasks one by one ofsimultaneously. It is the most important feature of computer. At one moment your are playing game oncomputer, the next moment you are composing and sending emails etc. In colleges and universitiescomputers are use to deliver lectures to the students. The talent of computer is dependent on thesoftware.9. CommunicationsToday computer is mostly used to exchange messages or data through computer networks all over theworld. For example the information can be received or send throug the internet with the help ofcomputer. It is most important feature of the modern information technology.10. DiligenceA computer can continually work for hours without creating any error. It does not get tired while workingafter hours of work it performs the operations with the same accuracy as well as speed as the first one.11. No FeelingsComputer is an electronic machine. It has no feelings. It detects objects on the basis of instructions givento it. Based on our feelings, taste, knowledge and experience: we can make certain decisions andjudgments in our daily life. On the other hand, computer can not make such judgments on their own.Their judgments are totally based on instructions given to them.12. ConsistencyPeople often have difficulty to repeat their instructions again and again. For example, a lecturer feelsdifficulty to repeat a same lecture in a class room again and again. Computer can repeat actionsconsistently (again and again) without loosing its concentration:To run a spell checker (built into a word processor) for checking spellings in a document.To play multimedia animations for training purposes.To deliver a lecture through computer in a class room etc. 19 | P a g e
20. 20. INTRODUCTION TO COMPUTERSA computer will carry out the activity with the same way every time. You can listen a lecture or performany action again and again.13. PrecisionComputers are not only fast and consistent but they also perform operations very accurately andprecisely. For example, in manual calculations and rounding fractional values (That is value with decimalpoint can change the actual result). In computer however, you can keep the accuracy and precision uptothe level, you desire. The length calculations remain always accurate.Computer is playing very important role in every field of life. Computers are everywhere such as athome, at school. In daily life a large number of activities are dependent on computers. The main fieldswhere computer is playing very important role are:1. EducationEducation is the process of developing knowledge through instructions. The instructions are receivedfrom people such as parents, teachers etc. and from printed material such as books, journals etc. Today,the modern technique to get knowledge is by using computers.All schools use computers in classrooms and labs to teach students. Many educators prefer to delivertheir lectures by computer-based presentations. In schools, colleges and universities, students usesoftware packages to complete their assignments.The computer-based training (CBT) or presentation is also called computer aided instruction (CAI). In thismethod, computer is used as an aid to teach the students in the classroom. The instructions of particularsubject are received from the instructions that uses a program presented by a computer as learningmedium. The web-based training (WBT) is another type of CBT that uses internet technology. It meansthat many websites provides online education. A lot of material of different topics is available on thesewebsites. They also provide online lectures and tutorials for the students. The CBT and WBT are used inbusiness education centers to educate people. People can get knowledge at very low cost as well as invery short period of time. Most of the WBT is free of cost.Eductainment is another type of CBT. It is a type of educational software that combines the educationwith entertainment. These software are available on CD-ROMs and DVD-ROMs and teach children in a funand in exciting way. Similarly typein is learnt through these types of software.2. Entertainment 20 | P a g e