BASIC CONCEPTS OF COMPUTER

1 BASIC CONCEPTS of COMPUTER :: 11 BASIC CONCEPTS OF INTRODUCTIONA COMPUTER is a programmable machine designed to performarithmetic and logical operations automatically andsequentially on the input given by the user and gives thedesired output after processing. COMPUTER components aredivided into two major categories namely hardware andsoftware. Hardware is the machine itself and its connecteddevices such as monitor, keyboard, mouse etc. Software arethe set of programs that make use of hardware for performingvarious OBJECTIVESA fter going through this lesson you would be able to: familiarise yourself with characteristics of computers identify the BASIC components of a COMPUTER explain the importance of various units of a COMPUTER differentiate between system software and applicationsoftware explain the importance of operating system get acquainted with open source appreciate the need of COMPUTER CHARACTERISTICS OF COMPUTERSThe characteristics of computers that have made them sopowerful and universally useful are speed, accuracy,diligence, versatility and storage capacity.

2 Let us discuss :: COMPUTER and Office ApplicationsSpeedComputers work at an incredible speed. A powerful computeris capable of performing about 3-4 million simple instructionsper addition to being fast, computers are also accurate. Errorsthat may occur can almost always be attributed to humanerror (inaccurate data, poorly designed system or faultyinstructions/programs written by the programmer)DiligenceUnlike human beings, computers are highly consistent. Theydo not suffer from human traits of boredom and tirednessresulting in lack of concentration. Computers, therefore, arebetter than human beings in performing voluminous andrepetitive are versatile machines and are capable ofperforming any task as long as it can be broken down into aseries of logical steps. The presence of computers can beseen in almost every sphere Railway/Air reservation, Banks,Hotels, Weather forecasting and many CapacityToday s computers can store large volumes of data. A pieceof information once recorded (or stored) in the COMPUTER ,can never be forgotten and can be retrieved COMPUTER : COMPUTER SystemBasic CONCEPTS of COMPUTER :: 3A COMPUTER system ( ) consists of mainly four basicunits; namely input unit, storage unit, central processingunit and output unit.

3 Central Processing unit further includesArithmetic logic unit and control unit, as shown inFigure COMPUTER performs five major operations or functionsirrespective of its size and make. These are it accepts data or instructions as input, it stores data and instruction it processes data as per the instructions, it controls all operations inside a COMPUTER , and it gives results in the form of Functional Unit: This unit is used for entering data andprograms into the COMPUTER system by the user : BASIC COMPUTER Unit: The storage unit is used for storing dataand instructions before and after processing. Dotted lines ( ) indicateflow of instruction solid lines( ) indicate flow of data4 :: COMPUTER and Office Unit: The output unit is used for storing theresult as output produced by the COMPUTER : The task of performing operations likearithmetic and logical operations is called Central Processing Unit (CPU) takes data andinstructions from the storage unit and makes all sorts ofcalculations based on the instructions given and the typeof data provided.

4 It is then sent back to the storage includes Arithmetic logic unit (ALU) and control unit(CU) Arithmetic Logic Unit: All calculations andcomparisons, based on the instructions provided, arecarried out within the ALU. It performs arithmeticfunctions like addition, subtraction, multiplication,division and also logical operations like greater than,less than and equal to etc. Control Unit: Controlling of all operations like input,processing and output are performed by control takes care of step by step processing of all operationsinside the MemoryComputer s memory can be classified into two types; primarymemory and secondary Memory can be further classified as RAM andROM. RAM or Random Access Memory is the unit in acomputer system. It is the place in a COMPUTER wherethe operating system, application programs and thedata in current use are kept temporarily so that theycan be accessed by the COMPUTER s processor. It issaid to be volatile since its contents are accessibleonly as long as the COMPUTER is on.

5 The contents ofRAM are no more available once the COMPUTER isturned CONCEPTS of COMPUTER :: 5 ROM or Read Only Memory is a special type of memorywhich can only be read and contents of which are notlost even when the COMPUTER is switched off. It typicallycontains manufacturer s instructions. Among otherthings, ROM also stores an initial program called the bootstrap loader whose function is to start theoperation of COMPUTER system once the power is Secondary MemoryRAM is volatile memory having a limited storage memory is storage other than theRAM. These include devices that are peripheral and areconnected and controlled by the COMPUTER to enablepermanent storage of programs and storage devices are of two types; magnetic andoptical. Magnetic devices include hard disks and opticalstorage devices are CDs, DVDs, Pen drive, Zip drive etc. Hard DiskFig. : Hard DiskHard disks are made up of rigid material and are usuallya stack of metal disks sealed in a box.

6 The hard disk andthe hard disk drive exist together as a unit and is apermanent part of the COMPUTER where data and programsare saved. These disks have storage capacities rangingfrom 1GB to 80 GB and more. Hard disks are :: COMPUTER and Office Applications Compact DiskCompact Disk (CD) is portable disk having data storagecapacity between 650-700 MB. It can hold large amountof information such as music, full-motion videos, andtext etc. CDs can be either read only or read write type. Digital Video DiskDigital Video Disk (DVD) is similar to a CD but has largerstorage capacity and enormous clarity. Depending uponthe disk type it can store several Gigabytes of data. DVDsare primarily used to store music or movies and can beplayed back on your television or the COMPUTER too. Theseare not Input / Output Devices:These devices are used to enter information and instructionsinto a COMPUTER for storage or processing and to deliver theprocessed data to a user. Input/Output devices are requiredfor users to communicate with the COMPUTER .

7 In simple terms,input devices bring information INTO the COMPUTER andoutput devices bring information OUT of a COMPUTER input/output devices are also known as peripheralssince they surround the CPU and memory of a )Input DevicesAn input device is any device that provides input to acomputer. There are many input devices, but the twomost common ones are a keyboard and mouse. Everykey you press on the keyboard and every movement orclick you make with the mouse sends a specific inputsignal to the COMPUTER . Keyboard: The keyboard is very much like a standardtypewriter keyboard with a few additional keys. The basicQWERTY layout of characters is maintained to make iteasy to use the system. The additional keys are includedto perform certain special functions. These are knownas function keys that vary in number from keyboard tokeyboard. (see fig. ) BASIC CONCEPTS of COMPUTER :: 7 Fig. : Keyboard Mouse: A device that controls the movement of the cursoror pointer on a display screen.

8 A mouse is a small objectyou can roll along a hard and flat surface (Fig. ). Itsname is derived from its shape, which looks a bit like amouse. As you move the mouse, the pointer on the displayscreen moves in the same : Mouse Trackball: A trackball is an input device used to entermotion data into computers or other electronic serves the same purpose as a mouse, but is designedwith a moveable ball on the top, which can be rolled inany direction. Touchpad: A touch pad is a device for pointing (controllinginput positioning) on a COMPUTER display screen. It is analternative to the mouse. Originally incorporated in laptopcomputers, touch pads are also being made for use withdesktop computers. A touch pad works by sensing theuser s finger movement and downward pressure. Touch Screen: It allows the user to operate/makeselections by simply touching the display screen. A display Function Keys Numeric Keypad Cursor Movement Keys Alphanumeric Keypad/ Special-function Keys 8 :: COMPUTER and Office Applicationsscreen that is sensitive to the touch of a finger or used on ATM machines, retail point-of-saleterminals, car navigation systems, medical monitors andindustrial control panels.

9 Light Pen: Light pen is an input device that utilizes alight-sensitive detector to select objects on a displayscreen. (Fig. )Fig. Light Pen Magnetic ink character recognition (MICR): MICR canidentify character printed with a special ink that containsparticles of magnetic material. This device particularlyfinds applications in banking industry. Optical mark recognition (OMR): Optical markrecognition, also called mark sense reader is a technologywhere an OMR device senses the presence or absence ofa mark, such as pencil mark. OMR is widely used intests such as aptitude test. Bar code reader: Bar-code readers are photoelectricscanners that read the bar codes or vertical zebra stripsmarks, printed on product containers. These devices aregenerally used in super markets, bookshops etc. Scanner: Scanner is an input device that can read textor illustration printed on paper and translates theinformation into a form that the COMPUTER can use.

10 Ascanner works by digitizing an image. (Fig. ) BASIC CONCEPTS of COMPUTER :: 9 Fig. Devices:Output device receives information from the CPU andpresents it to the user in the desired from. The processeddata, stored in the memory of the COMPUTER is sent to theoutput unit, which then converts it into a form that canbe understood by the user. The output is usuallyproduced in one of the two ways on the display device,or on paper (hard copy). Monitor: is often used synonymously with computerscreen or display. Monitor is an output device thatresembles the television screen (fig. ). It may use aCathode Ray Tube (CRT) to display information. Themonitor is associated with a keyboard for manual inputof characters and displays the information as it is keyedin. It also displays the program or application the television, monitors are also available in : Monitor10 :: COMPUTER and Office Applications Printer: Printers are used to produce paper (commonlyknown as hardcopy) output.