Recap of Lecture 02

1. Recap of Lecture 02 • Generations of Computer • Types of Computers • Classifications of Computers

2. INTRODUCTION TO Computer Lecture No 3 Computer Hardware Manual & Automatic Input Devices Output Devices

3. Computer Hardware • Hardware 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

4. Organization of Computer . Auxiliary Storage Input Units Output Units Main Memory & CPU (Central Processing Unit)

5. Input Unit • The 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.

6. Input & Output Devices

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

8. Manual Input Devices • A manual input device requires a human hand tocontrol it… Keyboard Mouse Camera Scanner

9. Manual Input Devices • A manual input device requires a human hand to control it… Tracker ball Joystick

10. Manual Input Devices Device Uses Advantages Disadvantages The most common input device You press keys to input data into the computer The most common type of keyboard is the QWERTY keyboard People are familiar with keyboards, so they don’t need to be trained Skilled typists can work very quickly They are very reliable and cheap Many people cannot type and look at the screen at the same time, so typing can be time consuming Keyboard

11. Manual Input Devices Uses Advantages Disadvantages Device Most common pointing device Used to point and click on icons or menus Combines well with a keyboard Fast and accurate Need a flat surface to use them Mouse A 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 limited Some people find that the thumb gets painful with prolonged use Ball can get greasy and dirty Tracker ball

12. Manual Input Devices Device Uses Advantages Disadvantages Originally designed forpilots to control aeroplanes Used to control wheelchairs and for playing games They give a more realistic gaming experience when playing games such as flight simulators Many different types available Some people find them difficult to operate. Joystick Used to convert printed images or text into a file of digital data The quality of the final image is dependent on the original image Images can be edited before use Scanner

13. Manual Input Devices Device Uses Advantages Disadvantages Used for taking still images which can be uploaded to a computer for permanent storage You can preview the image before pressing the shutter button No film needed or development costs Unwanted images can be deleted When the drive is full, images need to be uploaded to a computer or deleted Digital Camera A pointing device, built into a laptop for convenience Portable - built into the laptop Small movements needed to move the cursor Takes practice to master Touchpador Fingerpad

14. Automatic Input Devices • An 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. Microphone Barcode reader Webcam

15. Automatic Input Devices Device Uses Advantages Disadvantages Banks print important data on the bottom of cheques using magnetic ink This ink is then read by a computer Expensive to produce and print magnetic ink, and the reader is also expensive Banks are the main user – very few other applications 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 MICR MagneticInk Character Recognition

16. Automatic Input Devices Device Uses Advantages Disadvantages Used 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 humandata entry Sometimes incomplete marks are not read correctly OMR Optical MarkRecognition

17. Automatic Input Devices Uses Advantages Disadvantages Device Used to identify products in shops The code is read by a barcode scanner which identifies the product name, product size/weight manufacturer name All barcodes need to be programmed into the computer in advance Very quick and accurate way to enter data – suits busy shops Prices changes are made on the database, not the barcode Barcode Readers

18. Automatic Input Devices Device Uses Advantages Disadvantages Very cheap piece of equipment Helpful for people with additional needs or for busy people who need very quick letters Used to input sound into the computer Used to give the computer commands, or to dictate letters directly to a word processor Computer can misread voice instructions due to natural variations in people’s voices Microphone Very cheap piece of equipment Enables people to see each other The moving picture tends to flicker due to current limitations in data transfer Used to input moving images into the computer for use in online communication Webcam

19. Output Devices

20. Output Devices • An output device is used to display or use information that comes out of a computer system. • Output devicesconvert electrical signals from a computer system into… • Sound (speakers or headphones) • Images ,video & Text (screen or printer)

21. Output Devices Monitor Speakers Printer Headphones Plotter

22. Output Devices Uses Disadvantages Device Advantages Take up very little space Run very quietly and produce little heat Use about a third of the energy ofa CRT monitor Thin Film Transistor monitors are more commonly known as flat screens or LCD screens Easy to damage Colour contrast on cheaper models is not as good as CRT monitors TFT Monitor Cathode Ray Tube is very old technology.Almost completely replaced by flat screen monitors Reliable Last for a very long time Large Can be heavy Produce a lot of heat Old technology CRT Monitor

23. Output Devices Uses Advantages Disadvantages Device Speakers are not useful in a network room, as everyone would disturb each other Headphones can be uncomfortable with extended use When connected to a computer through a sound card, music can be played Gives feedback to user during general computer use Games are a lot more involving and realisticwith sound Speakers & Headphones These are specialist printers that can produce high quality printoutson large piecesof paper Very high quality printouts Almost any size paper can be used Slower than normal printers Expensive Plotter

24. Printers There are 3 main types of printer… Device Uses Advantages Disadvantages Inkjet General purposeuse for family orhome office Cheap to buy Latest modelscan be very fast Ink cartridges can be very expensive Business use for letters,stationery and images Quality printing Good for large areas of colour Quiet & Quick Laser More expensive to buy than inkjets Toner cartridges are expensive Can make a carbon copy Can print on continuousrolls of paper Noisy and rather old-fashioned technology Poor quality and only prints in black ink Dot Matrix Business usefor duplicatedocuments

25. Soft copy • The 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)

26. Hard copy • The 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: • Printer • Plotters

27. Summary • Introduction to Computer Hardware • Input Unit ,Out Put Devices. • Different Types of Manual & Automatic Input Devices • Out Put Devices • Soft Copy • Hard Copy