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Recap of Lecture 02  Generations of Computer  Types of Computers  Classifications of Computers.

Jan 16, 2016



  • Recap of Lecture 02Generations of ComputerTypes of ComputersClassifications of Computers


    Lecture No 3

    Computer Hardware

    Manual & Automatic Input Devices

    Output Devices

  • Computer HardwareHardware are the electronic and mechanical components of a computer systems.Physical components and which can be touched, handle or seen physically.Despite the difference in performance among the different kinds of computers, every digital computer is made up of four basic units,Input Unit (Input Devices are used to enter data into the Computer)Out Put Unit (Out Devices are used to see the result of Processed Data )Central Processing Unit (CPU)Secondary Storage

  • Organization of Computer.Main Memory&CPU(Central Processing Unit)InputUnitsOutputUnitsAuxiliary Storage

  • Input UnitThe initial unit which provides communications between the user and the computer is the input unit.This unit describes a device used to transfer information into a computing system. The devices used to give data or commands to computer are called Input devices.

  • Input & Output Devices

  • Input DevicesData or information can be fed into computer by using different peripherals i.e. types of input devices. Two types of input devicesManual Input Devices Automatic Input Devices

  • Manual Input DevicesA manual input device requires a human hand to control it MouseKeyboardScannerCamera

  • Manual Input DevicesTracker ballJoystickA manual input device requires a human hand to control it

  • Manual Input DevicesKeyboardThe most common input deviceYou press keys to input data into the computerThe most common type of keyboard is the QWERTY keyboardPeople are familiar with keyboards, so they dont need to be trainedSkilled typists can work very quicklyThey are very reliable and cheap Many people cannot type and look at the screen at the same time, so typing can be time consumingUsesAdvantagesDisadvantagesDevice

  • Manual Input DevicesMouse Most common pointing deviceUsed to point and click on icons or menus Combines well with a keyboardFast and accurateNeed a flat surface to use themTracker ballA tracker ball is basically an upside down ball mouse.The user runs their thumb over the ball to control the on-screen pointer Useful where desk space is limitedSome people find that the thumb gets painful with prolonged useBall can get greasy and dirty UsesAdvantagesDisadvantagesDevice

  • Manual Input DevicesUsesAdvantagesDisadvantagesDeviceScanner Used to convert printed images or text into a file of digital data Images can be edited before use The quality of the final image is dependent on the original imageJoystick Originally designed for pilots to control aeroplanesUsed to control wheelchairs and for playing gamesThey give a more realistic gaming experience when playing games such as flight simulatorsMany different types available Some people find them difficult to operate.

  • Manual Input DevicesDigital Camera Used for taking still images which can be uploaded to a computer for permanent storage You can preview the image before pressing the shutter buttonNo film needed or development costsUnwanted images can be deletedWhen the drive is full, images need to be uploaded to a computer or deletedTouchpad or Fingerpad A pointing device, built into a laptop for convenience Portable - built into the laptopSmall movements needed to move the cursorTakes practice to masterUsesAdvantagesDisadvantagesDevice

  • Automatic Input DevicesAn automatic input device inputs data without the need for human intervention (once the device has been set up), e.g. MICR, OMR, barcode reader, webcam, microphone.MicrophoneWebcamBarcode reader

  • Automatic Input DevicesMICRMagnetic Ink Character RecognitionBanks print important data on the bottom of cheques using magnetic inkThis ink is then read by a computer Very quick and accurate processing of data very low error rate. Very secure as any attempt to change the numbers on a cheque will be ignored as the reader only recognises magnetic ink in the same font Expensive to produce and print magnetic ink, and the reader is also expensiveBanks are the main user very few other applicationsUsesAdvantagesDisadvantagesDevice

  • Automatic Input DevicesOMROpticalMark RecognitionUsed to mark multiple choice exam papers, National Testing Service (NTS) use OMR for paper checking .Very fast method of reading data, which save time. More accurate than human data entrySometimes incomplete marks are not read correctlyUsesAdvantagesDisadvantagesDevice

  • Automatic Input DevicesBarcode Readers Used to identify products in shopsThe code is read by a barcode scanner which identifies the product name, product size/weight manufacturer nameVery quick and accurate way to enter data suits busy shops Prices changes are made on the database, not the barcodeAll barcodes need to be programmed into the computer in advanceUsesAdvantagesDisadvantagesDevice

  • UsesAdvantagesDisadvantagesDeviceMicrophone Used to input sound into the computerUsed to give the computer commands, or to dictate letters directly to a word processor Very cheap piece of equipmentHelpful for people with additional needs or for busy people who need very quick lettersComputer can misread voice instructions due to natural variations in peoples voicesAutomatic Input DevicesWebcam Used to input moving images into the computer for use in online communication Very cheap piece of equipmentEnables people to see each otherThe moving picture tends to flicker due to current limitations in data transfer

  • Output Devices

  • Output DevicesAn output device is used to display or use information that comes out of a computer system.Output devices convert electrical signals from a computer system intoSound (speakers or headphones)Images ,video & Text (screen or printer)

  • Output DevicesMonitorSpeakersPlotterHeadphonesPrinter

  • Output DevicesTFT Monitor Thin Film Transistor monitors are more commonly known as flat screens or LCD screens Take up very little spaceRun very quietly and produce little heatUse about a third of the energy of a CRT monitor Easy to damageColour contrast on cheaper models is not as good as CRT monitorsUsesAdvantagesDisadvantagesDeviceCRT Monitor Cathode Ray Tube is very old technology. Almost completely replaced by flat screen monitorsReliableLast for a very long time LargeCan be heavyProduce a lot of heat Old technology

  • Output DevicesSpeakers& Headphones When connected to a computer through a sound card, music can be playedGives feedback to user during general computer useGames are a lot more involving and realistic with soundSpeakers are not useful in a network room, as everyone would disturb each otherHeadphones can be uncomfortable with extended use UsesAdvantagesDisadvantagesDevicePlotter These are specialist printers that can produce high quality printouts on large pieces of paper Very high quality printoutsAlmost any size paper can be usedSlower than normal printersExpensive

  • PrintersThere are 3 main types of printerDot MatrixLaserInkjetUsesAdvantagesDisadvantagesDeviceGeneral purpose use for family or home officeCheap to buyLatest models can be very fastInk cartridges can be very expensiveBusiness use for letters, stationery and imagesQuality printingGood for large areas of colourQuiet & QuickMore expensive to buy than inkjetsToner cartridges are expensiveBusiness use for duplicate documentsCan make a carbon copyCan print on continuous rolls of paperNoisy and rather old-fashioned technologyPoor quality and only prints in black ink

  • Soft copyThe result (text/graphics ) appear on displayed screen are known as soft copy and will disappear if display is switched off.Therefore this form of output is not permanent and can be removed, changed or corrected.Output devices used for soft copy:Visual display unit (monitor or TV screen)

  • Hard copyThe results (text/graphics) printed on paper is known as Hard Copy.It is considered as permanent copy and can be retained even computer is turned off.Output devices used for Hard copy:PrinterPlotters

  • SummaryIntroduction to Computer HardwareInput Unit ,Out Put Devices.Different Types of Manual & Automatic Input DevicesOut Put Devices Soft CopyHard Copy