Chapter-1 OVERVIEW OF COMPUTER

Chapter 1- Overview of ComputersMDRPUC, HassanChapter-1OVERVIEW OF COMPUTERDefinition:“Computer is an electronic machine that can store, recall and process data. It can perform tasksor complex calculation according to a set of instructions or programs.How does the computer work?It is as simple as making tea. To prepare tea, we add water, tea powder, milk, and sugar. These are allconsidered as input. After adding all, we have to boil. That boiling is called processing. After boiling,we get tea. That is called output.Similarly, the computer works based on the input, processing and output.Input-Process-Output cycle (IPO Cycle)Characteristics of Computer: Speed Versatility Storage Flexibility Accuracy Cost effectiveness Diligence Speed:The computer works very fast. The speed of Computer is measured in terms of MIPS (MillionInstructions Per Second) or BIPS (Billion Instructions Per Second).For Example A money counting machine counts money faster than man.1 Page

Chapter 1- Overview of ComputersMDRPUC, Hassan Storage:The computer can store a large volume of data and information. The storage capacity of thecomputer is measured in terms of Bytes. A group of 8 Bits is called a Byte. AccuracyThe computer generated results are exact and without any mistakes with high rate ofconsistency. DiligenceUnlike human beings, a computer does not suffer from limitations like tiredness and lack ofconcentration. It can work for hours without making any errors. VersatilityComputers are capable of performing any task. Multi-processing features of computer make itquite versatile in nature. The computer can be adapted to any field easily. It is used for scientificcalculations, business processing, for playing games, teaching, training etc. FlexibilityFlexibility would involve the number of things you can do with a computer. While some arebest used for simple business tasks, and filing of tasks, others are good for multimedia, gaming, and soon. Cost effectivenessComputers reduce the amount of paper work and human effort, thereby reducing costs.Components of Computer system:There are four components in the computer system. They are: Hardware Data & Information Software User(s)HardwareThe physical parts of a computer system called as hardware. The hardware components can beseen, touch and feel. The hardware components are fixed inside or outside the computer system.Example Keyboard, Mouse, Monitor, Printer, RAM, CPU etc.2 Page

Chapter 1- Overview of Computers MDRPUC, HassanSoftwareA Set or collection of programs is known as software. The software is a computer programwritten using some computer programming languages to operate the computer. Software tells thehardware what to do. Unlike hardware, we can’t touch the software.Example Operating System, TUX Paint, Office Packages, Nudi, Adobe Reader, ComputerGames etc.The software is broadly classified into two types. They are1. System Software: It is a type of computer program that is designed to control and work withcomputer hardware, to run a computer's hardware and application programs.Example: Microsoft Windows, Linux, DOS etc.2. Application software: It is a type of Software written by the user to perform a particular task likedrawing a picture, playing computer games.Example: Paint, Nudi and Office Package etc. Difference between Hardware and SoftwareHardwarePhysical components of a computer arecalled Hardware.Hardware can touch, see and feel.SoftwareSet of programs is called Software.The software can not touch and feel.Constructed using physical materials or Developed bytheprogrammingcomponents.language.Not affected by computer viruses.Affected by computer viruses.User cannot make copiesUser can make copiesExample: Monitor, Keyboard, RAMExample: OS, Text Editor, NudiDataData is a collection of unprocessed items, which can include text, numbers, audio or video. Datais the raw information or basic facts that computer can process.For Example: “PARAM” 16The computer processed data is called information, which gives particular meaning.For Example: Name “PARAM” Age 16.3 Page

Chapter 1- Overview of Computers MDRPUC, HassanUser(s)People who use the computers are called users. These computer operators are called computerusers.Functional components of a computer:Basically any computer is supposed to carry out the following functions. Accepts the data and program as input. Stores the data, program and retrieve as and when required. Process the data as per instructions given by the program and convert it into usefulinformation. Communicate the information as output.Block diagram of a computerA computer is designed using four basic units. They are:1. Input Unit2. Central Processing Unit(CPU) Control Unit Arithmetic and Logic Unit (ALU)3. Memory Unit4. Output UnitControl UnitInput UnitOutput UnitArithmetic &Logic UnitCPUMemory UnitPrimary MemorySecondary MemoryFig: Block Diagram of Computer4 Page

Chapter 1- Overview of Computers MDRPUC, HassanInput UnitComputers need to receive data and instructions in order to solve a problem. The Input unitperforms this operation. The Input Unit basically links the external world or environment to thecomputer system. The input unit may consist of one or more input devices. The Keyboard and mouseof a computer are the most commonly used input devices. Central Processing Unit (CPU)It is the main part of a computer system like the heart of a human being. Most computers areidentified by the type of CPU that is present in them. The function of the CPU is to interpret theinstructions in the program and execute them one by one. It consists of two major units.1. Control Unit: It controls and directs the transfer of program instructions and data betweenvarious units. The main activity is to maintain order and direct the operations of the entiresystem.2. Arithmetic and Logic Unit (ALU): Arithmetic and Logic Unit performs arithmetic andlogical operations and controls the speed of these operations. Arithmetic operations likeaddition, subtraction, multiplication and division ( ,-,*, /) and logical operations like AND,OR, NOT and relational operations like ( , , , ) are being carried out in this unit. Memory UnitThe data and the instructions required for processing have to be stored in the memory unit beforethe actual processing starts. In a similar manner, the results generated from processing have to bepreserved before it is displayed. The memory units thus provide space to store input data, intermediateresults and the final output generated.Secondary storage devices are additional memory (storage) devices such as floppy disks,magnetic tapes, Hard Disk Drive (HDD), Compact Disk (CD), Digital Versatile Disk (DVD) etc.,which are used to store huge information for future use.Note: The input unit, an output unit, and secondary storage devices are together known asPeripheral Devices. Output UnitIt is used to print or display the results, which are stored in the memory unit. The actualfunction of the output unit is just the reverse of the input unit. Thus, the output unit links the computerto the outside world. The Monitor and Printer are the most commonly used output devices.5 Page

Chapter 1- Overview of ComputersMDRPUC, HassanEvolution of computer: AbacusApproximately 4,000 years ago, the Chinese invented the Abacus. It was the first machine usedfor counting and calculating. It is made of a wooden frame, metal rods, and wooden beads Abacuswas mainly used for addition, subtraction and later for division and multiplication. Today, the abacusis still used widely in China and other Asian countries to count and calculate, just as we usecalculators. Napier’s bonesIn the early 17th century, John Napier, a Scottish mathematician, invented another calculatingtool. “Napier’s bones” was based upon manipulation of rods with printed digits. The rods were madeof bone, ivory, wood or metal. The set consists of 10 rectangular blocks with multiples of a differentdigit on each of the four sides. The slide RuleThe slide Rule was invented by William Oughtred. It is based on the principle that acutaldistance from the starting point of the rule is directly proportional to the logarithm of the numbersprinted on the rule. The slide rule is emboided by the two sets of scales that are joined together, with amarginal space between them. Adding Machine-PascalineIn 1642, at the age of 19, a French mathematician by the name of Biaise Pascal invented thePascaline. The Pascaline is known as the first mechanical and automatic calculator.The Pascaline was a wooden box that could only add and subtract by means of a series of gearsand wheels. It had a box with eight movable wheels called dials. When each wheel rotated onerevolution, it would then turn the neighboring wheel. Leibniz CalculatorMathematician Gottfried Leibniz built a calculator in 1650 that could add, substract, multiplyand divide the numbers. Jacquard loomIn 1801, Joseph Mary Jacquard invented the Jacquard loom. A poweed loom that usedpunched wooden cards to automatically weave incredibly detailed patterns including pictures and text.This can be taken as the first “Read only Memory” device.6 Page

Chapter 1- Overview of Computers MDRPUC, HassanDifference and Analytical EngineIn the early 1820s, an English mathematician by the name Charles Babbage designed acomputing machine called the Difference Engine. This machine was to be used in the calculating andprinting of simple math tables. In the 1830s, he designed a second computing machine called theAnalytical Engine. This machine consited five units, which became the basic principle for thedevelopment of modern computer. Hence Charles Babbage is known as the "Father of Computers”. 1833-First ProgrammerLady Ada Lovelace was a first computer programmer, who designed program for Babbage’sAnalytical Engine. 1890 AD – Hollerith Tabulating MachineIn 1889, an American named Herman Hollerith invented a counting machine to count thepopulation of USA. This electronic machine is able to read the information on the punched cards andprocess it electronically. Herman Hollerith was the founder of the company than became famous asIBM.Generations of ComputerDepending on the development of the technology the generation of computer is classified intofive generations. First Generation of Computer (1940-1956)1. The first generation of computers is started with using vacuum tubes as the basic components.2. The speed of these computers was very slow, storage capacity was very less and these computersare large in size.3. This generation computers operated only on machine language.4. Input was based on punched card, paper tapes an output was obtained as printout.Some computers of this generation were ENIAC (Electronic Numerical Integrator andCalculator), UNIVAC (Universal Automatic Computer).ENIAC: It stands for Electrical Numerical Integrator and Computer. It used a word of ten decimal digits instead of binary ones like previous automated calculators/computers.7 Page