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Chapter 6

  1. 1. Chapter 6 Input and Output Devices 6.1 Input Devices 104 6.2 Output Devices 118
  2. 2. 6.1 Input Devices (1) <ul><li>Input Devices </li></ul><ul><ul><li>Peripheral devices for entering data, instructions and user responses </li></ul></ul><ul><ul><li>Produce machine readable data </li></ul></ul><ul><li>Online Operations </li></ul><ul><ul><li>Data are directly input into the memory of the computer </li></ul></ul><ul><li>Offline Operations </li></ul><ul><ul><li>Punched cards were prepared with a keypunching machine before they are inputted into the computer </li></ul></ul>Chapter 6 I/O Devices
  3. 3. 6.1 Input Devices (2) <ul><li>Input devices may be categorised into eight groups: </li></ul><ul><ul><li>Keyboard </li></ul></ul><ul><ul><li>Pointing Devices </li></ul></ul><ul><ul><li>Scanner and Reader </li></ul></ul><ul><ul><li>Voice Input </li></ul></ul><ul><ul><li>Digital Camera </li></ul></ul><ul><ul><li>Video Input </li></ul></ul><ul><ul><li>Authentication Devices </li></ul></ul><ul><ul><li>Data-logger </li></ul></ul>Chapter 6 I/O Devices
  4. 4. 6.1.1 Keyboard (1) <ul><li>Standard QWERTY Keyboard </li></ul><ul><ul><li>Some Extra keys </li></ul></ul><ul><ul><ul><li>like arrow key, function keys etc </li></ul></ul></ul><ul><ul><li>Enter Key </li></ul></ul><ul><ul><ul><li>Use in issuing command </li></ul></ul></ul><ul><ul><li>Num-Lock and Insert Key </li></ul></ul><ul><ul><ul><li>Toggle between 2 states </li></ul></ul></ul><ul><ul><li>Special Keys (Shift, Ctrl and Alt) </li></ul></ul><ul><ul><ul><li>Use with other keys to increase the function of a keyboard </li></ul></ul></ul>6.1 Input devices
  5. 5. 6.1.1 Keyboard (2) <ul><li>Cordless keyboard </li></ul><ul><ul><li>Data is sent through radio or infrared radiation </li></ul></ul><ul><ul><li>So, requires a receiver </li></ul></ul><ul><ul><ul><li>which is connected to a port on the system unit </li></ul></ul></ul><ul><ul><li>Require a battery to operate </li></ul></ul><ul><li>Non-standard keyboards </li></ul><ul><ul><li>Point-of-sales (POS) terminals of supermarkets </li></ul></ul><ul><ul><ul><li>to speed up data input </li></ul></ul></ul><ul><ul><li>Keypads in automatic teller machines (ATM) </li></ul></ul><ul><ul><ul><li>to limit users to certain keys only </li></ul></ul></ul>6.1 Input devices
  6. 6. 6.1.2 Pointing Devices (1) <ul><li>A pointing device </li></ul><ul><ul><li>An input device </li></ul></ul><ul><ul><li>Controlling a pointer on the screen </li></ul></ul><ul><ul><ul><li>A pointer can be </li></ul></ul></ul><ul><ul><ul><ul><li>an arrow, an I-beam or a pointing hand </li></ul></ul></ul></ul><ul><ul><li>Used in Graphical user interface (GUI) </li></ul></ul><ul><ul><ul><li>clicking buttons </li></ul></ul></ul><ul><ul><ul><li>selecting menu items </li></ul></ul></ul><ul><ul><ul><li>moving the insertion point </li></ul></ul></ul><ul><ul><ul><li>selecting text </li></ul></ul></ul><ul><ul><ul><li>drawing pictures </li></ul></ul></ul><ul><ul><ul><li>accepting handwriting script </li></ul></ul></ul><ul><ul><ul><ul><li>which is later converted into typescript </li></ul></ul></ul></ul>6.1 Input devices
  7. 7. 6.1.2 Pointing Devices (2) <ul><li>1. Mouse </li></ul><ul><li>2. Trackball </li></ul><ul><li>3. Joystick and Wheels </li></ul><ul><li>4. Graphic Tablets </li></ul><ul><li>5. Touch Screen </li></ul><ul><li>6. Touchpad </li></ul><ul><li>7. Pointing Stick </li></ul>6.1 Input devices
  8. 8. Mouse (1) <ul><ul><li>Normally with two buttons and a small wheel </li></ul></ul><ul><ul><li>Moved under user’s palm </li></ul></ul><ul><li>Mechanical mouse </li></ul><ul><ul><li>Has a ball on its underside </li></ul></ul><ul><ul><li>A circuit converts movement into electrical signals </li></ul></ul><ul><li>Optical mouse </li></ul><ul><ul><li>Emits light and senses the reflected light to detect the mouse's movement. </li></ul></ul><ul><ul><li>Does not require cleaning, but </li></ul></ul><ul><ul><li>More expensive. </li></ul></ul>6.1.2 Pointing Devices
  9. 9. Mouse (2) <ul><li>Movement of mouse </li></ul><ul><ul><li>Relative </li></ul></ul><ul><ul><ul><li>The screen pointer moves from its current location. </li></ul></ul></ul><ul><ul><li>Work by the point-and-click principle </li></ul></ul><ul><li>Cordless mouse </li></ul><ul><ul><li>Battery-powered </li></ul></ul><ul><ul><li>Use radio or infrared radiation to communicate with the system unit </li></ul></ul>6.1.2 Pointing Devices
  10. 10. Trackball <ul><ul><li>An upside-down mechanical mouse </li></ul></ul><ul><ul><li>To control the screen pointer, no need to move the device </li></ul></ul><ul><ul><li>Rotate the ball with a finger </li></ul></ul><ul><ul><li>Requires frequent cleaning </li></ul></ul>6.1.2 Pointing Devices
  11. 11. Joystick and Wheel <ul><li>Joystick </li></ul><ul><ul><li>used in computer games </li></ul></ul><ul><ul><li>consists of a vertical lever mounted on a base and some buttons </li></ul></ul><ul><ul><li>The lever allows movement in different directions </li></ul></ul><ul><ul><li>Buttons activate actions </li></ul></ul><ul><ul><ul><li>e.g. jumping and firing. </li></ul></ul></ul><ul><li>Wheel </li></ul><ul><ul><li>Control vehicle in driving simulation software </li></ul></ul><ul><ul><li>Sometimes include foot pedals for acceleration and braking actions </li></ul></ul>6.1.2 Pointing Devices
  12. 12. Graphic tablet <ul><ul><li>also called digitiser </li></ul></ul><ul><ul><li>flat rectangular electronic board </li></ul></ul><ul><ul><li>used with a pen or cursor </li></ul></ul><ul><li>Movement of the pen </li></ul><ul><ul><li>Absolute </li></ul></ul><ul><ul><li>The x-y coordinates of the screen and the graphic tablet match with each other </li></ul></ul><ul><li>Handwriting Recognition software </li></ul><ul><ul><li>Inputting Chinese characters </li></ul></ul><ul><ul><li>translate scripts drawn on the screen into character codes </li></ul></ul>6.1.2 Pointing Devices
  13. 13. Touch screen <ul><ul><li>Pressure-sensitive display </li></ul></ul><ul><ul><li>Allows selecting option with fingers </li></ul></ul><ul><ul><li>Suitable for small amount of data input </li></ul></ul><ul><ul><li>Examples </li></ul></ul><ul><ul><ul><li>Kiosks located in stores, museums and airports </li></ul></ul></ul><ul><ul><ul><li>Modern pay-phone system uses touch screen to replace physical numeric keypads </li></ul></ul></ul><ul><ul><li>Handheld computers (PDA) and tablet PC </li></ul></ul><ul><ul><ul><li>Without keyboard or mouse </li></ul></ul></ul><ul><ul><ul><li>Mainly use pressure-sensitive computer screen </li></ul></ul></ul><ul><ul><ul><li>Handwriting recognition software translates handwritten letters and symbols into text </li></ul></ul></ul>6.1.2 Pointing Devices
  14. 14. Touchpad <ul><ul><li>Built-in pointing device of some notebook computers </li></ul></ul><ul><ul><li>Sensitive to pressure and motion </li></ul></ul><ul><ul><li>With buttons similar to the mouse buttons </li></ul></ul><ul><ul><li>May tap the touchpad to imitate mouse click </li></ul></ul>6.1.2 Pointing Devices
  15. 15. Pointing stick <ul><ul><li>Built-in pointing device of some notebook computers </li></ul></ul><ul><ul><li>Look like a pencil eraser </li></ul></ul><ul><ul><li>Located between keys on the keyboard </li></ul></ul><ul><ul><li>Movement is controlled by a finger </li></ul></ul>6.1.2 Pointing Devices
  16. 16. 6.1.3 Scanners/Reading Devices <ul><li>1. Image Scanner </li></ul><ul><li>2. OCR Reader </li></ul><ul><li>3. OMR Reader </li></ul><ul><li>4. Barcode Reader </li></ul><ul><li>5. MICR Reader </li></ul>6.1 Input Devices
  17. 17. Image Scanner <ul><li>Image Scanner </li></ul><ul><ul><li>Light-sensitive input device </li></ul></ul><ul><ul><li>Reads printed text and photos by </li></ul></ul><ul><ul><ul><li>sending a bright light on the document and detecting the light reflected from the document </li></ul></ul></ul><ul><ul><li>Convert the document into digital images </li></ul></ul><ul><li>Optical Character Recognition (OCR) </li></ul><ul><ul><li>Analyse digital images </li></ul></ul><ul><ul><li>Translate the results into text characters </li></ul></ul><ul><ul><ul><li>which can be edited by a word processor </li></ul></ul></ul>6.1.3 Scanner/Reader
  18. 18. OCR Reader <ul><li>OCR reader </li></ul><ul><ul><li>range from large machines to handheld wands </li></ul></ul><ul><ul><li>Some OCR devices can only read the OCR fonts </li></ul></ul><ul><ul><li>OCR-A is the widely used OCR font </li></ul></ul>6.1.3 Scanner/Reader
  19. 19. OMR Reader <ul><li>Optical Mark Recognition (OMR) Reader </li></ul><ul><ul><li>detects pencil mark on paper </li></ul></ul><ul><ul><li>Commonly used in marking multiple-choice answer sheets </li></ul></ul>6.1.3 Scanner/Reader
  20. 20. Bar code reader <ul><li>Bar code </li></ul><ul><ul><li>consists of a set of parallel lines and spaces of different widths </li></ul></ul><ul><ul><li>is an identification code, commonly used in </li></ul></ul><ul><ul><ul><li>libraries, post offices, publishing companies, manufacturers etc. </li></ul></ul></ul><ul><li>Bar code readers </li></ul><ul><ul><li>Highly accurate and fast </li></ul></ul><ul><ul><li>Printed with the letters that represent the code </li></ul></ul><ul><ul><ul><li>for manual input when the bar code cannot be recognised </li></ul></ul></ul>6.1.3 Scanner/Reader
  21. 21. MICR Reader <ul><li>Magnetic Ink Character Recognition (MICR) Reader </li></ul><ul><ul><li>Read text printed with magnetised ink </li></ul></ul><ul><ul><li>Exclusively used by bank for cheque processing </li></ul></ul>6.1.3 Scanner/Reader
  22. 22. 6.1.4 Voice Input <ul><li>Voice input </li></ul><ul><ul><li>Input data by speaking to a microphone </li></ul></ul><ul><ul><li>Sound card converts sound waves into digital form </li></ul></ul><ul><li>Voice recognition </li></ul><ul><ul><li>Distinguishes spoken words </li></ul></ul><ul><ul><li>Matches the input wave patterns with the patterns stored inside the computer </li></ul></ul><ul><ul><li>Useful for physically handicapped people </li></ul></ul>6.1 Input Devices
  23. 23. 6.1.5 Digital Camera <ul><li>Digital Camera </li></ul><ul><ul><li>Take still pictures </li></ul></ul><ul><ul><li>Produce bitmap images, e.g. JPG </li></ul></ul><ul><ul><li>Storing in flash memory/card </li></ul></ul><ul><ul><li>Transferring to computer through card reader </li></ul></ul><ul><ul><li>The storage media can be reused </li></ul></ul>6.1 Input Devices
  24. 24. 6.1.6 Video Input (1) <ul><li>1. Video capture card </li></ul><ul><ul><li>Converts image in analog form into digital form </li></ul></ul><ul><li>2. DV camera </li></ul><ul><ul><li>also called camcorder </li></ul></ul><ul><ul><li>Records videos as digital signals </li></ul></ul><ul><ul><li>Signals transmitted directly to a computer or </li></ul></ul><ul><ul><li>stored in tapes </li></ul></ul>6.1 Input Devices
  25. 25. 6.1.6 Video Input (2) <ul><li>3. Web cam </li></ul><ul><ul><li>Capture motions and send video signals to computer directly </li></ul></ul><ul><ul><li>Cannot be used alone (must be used with computer) </li></ul></ul><ul><ul><ul><li>Commonly used in videoconferencing. </li></ul></ul></ul><ul><li>Videoconferencing </li></ul><ul><ul><li>allows geographically separated people to meet one another, via Internet to transmit audio and video data. </li></ul></ul><ul><ul><li>Besides the videoconferencing software, user need </li></ul></ul><ul><ul><ul><li>microphone </li></ul></ul></ul><ul><ul><ul><li>speaker and </li></ul></ul></ul><ul><ul><ul><li>Web cam/DV camera </li></ul></ul></ul>6.1 Input Devices
  26. 26. 6.1.7 Authentication Devices <ul><li>Authentication Devices </li></ul><ul><ul><li>Verify the identity of a user </li></ul></ul><ul><ul><li>Input the identification code into the computer </li></ul></ul><ul><li>1. Magnetic Card Reader </li></ul><ul><li>2. Smart Card Reader </li></ul><ul><li>3. Fingerprint Scanner </li></ul><ul><li>4. Other biometric Devices </li></ul>6.1 Input Devices
  27. 27. Magnetic Card Reader <ul><li>Magnetic Card Reader </li></ul><ul><ul><li>Reads the magnetic stripe on the back of a bank card </li></ul></ul><ul><ul><li>The magnetic stripe stores the customer's account number only </li></ul></ul><ul><ul><li>Updating is done at the bank's computer </li></ul></ul>6.1.7 Authentication Devices
  28. 28. Smart Card Reader <ul><li>Smart Card </li></ul><ul><ul><li>embedded with a microprocessor and memory </li></ul></ul><ul><ul><li>Holding much more information than a magnetic card </li></ul></ul><ul><li>A smart card can be programmed </li></ul><ul><ul><li>If wrong passwords are entered several times, it would be self-destructed </li></ul></ul><ul><ul><li>More secure </li></ul></ul><ul><ul><li>Can be used in financial transactions, like </li></ul></ul><ul><ul><ul><li>stored-value ticket for public transport, where it is loaded with digital money </li></ul></ul></ul>6.1.7 Authentication Devices
  29. 29. Fingerprint Scanners <ul><li>Fingerprint Scanners </li></ul><ul><ul><li>Biometric authentication device </li></ul></ul><ul><ul><li>Captures curves and indentations of a fingerprint </li></ul></ul><ul><ul><li>Sends the data into a computer for verification. </li></ul></ul><ul><ul><li>Some notebook computer uses this security technique to protect the computer </li></ul></ul>6.1.7 Authentication Devices
  30. 30. Other biometric authentication devices <ul><li>Biometric authentication devices </li></ul><ul><ul><li>Fingerprint Scanner </li></ul></ul><ul><ul><li>Face Recognition System </li></ul></ul><ul><ul><li>Hand Geometry Detection </li></ul></ul><ul><ul><li>Voice Recognition </li></ul></ul><ul><ul><li>Iris Pattern Matching </li></ul></ul>6.1.7 Authentication Devices
  31. 31. 6.1.8 Data-loggers <ul><li>Data-loggers </li></ul><ul><ul><li>used in some school laboratories </li></ul></ul><ul><ul><li>collect and analyse data </li></ul></ul><ul><ul><li>replace some traditional apparatus </li></ul></ul><ul><ul><li>Consists of one or more sensors, such as </li></ul></ul><ul><ul><ul><li>temperature sensor </li></ul></ul></ul><ul><ul><ul><li>pressure sensor </li></ul></ul></ul><ul><ul><ul><li>heartbeat rate sensor </li></ul></ul></ul><ul><ul><li>Special data analysis software is needed </li></ul></ul><ul><ul><ul><li>to display the captured data in digits, tables or graphs </li></ul></ul></ul>6.1 Input Devices
  32. 32. 6.2 Output Devices <ul><li>1. Display Devices </li></ul><ul><li>2. Printers </li></ul><ul><li>3. Speakers and Headset </li></ul>Chapter 6 I/O Devices
  33. 33. 6.2.1 Display Devices (1) <ul><li>Visual Display Unit (VDU) </li></ul><ul><ul><li>Most frequently used output device </li></ul></ul><ul><ul><li>Monitor is a separate unit </li></ul></ul><ul><li>Two technologies for VDU: </li></ul><ul><ul><li>Cathode Ray Tubes (CRT) </li></ul></ul><ul><ul><ul><li>Produce images as electrons strike on a fluorescent screen </li></ul></ul></ul><ul><ul><ul><li>Operate at very high voltage </li></ul></ul></ul><ul><ul><ul><li>Require many electronic components. </li></ul></ul></ul><ul><ul><li>Liquid Crystal Display (LCD) </li></ul></ul><ul><ul><ul><li>Thin and light, known as flat-panel display </li></ul></ul></ul><ul><ul><ul><li>used in notebook computers, tablet PC, handheld computers and mobile devices </li></ul></ul></ul>6.2 Output Devices
  34. 34. 6.2.1 Display Devices (2) <ul><li>Display devices </li></ul><ul><ul><li>Display information visually </li></ul></ul><ul><li>Softcopy </li></ul><ul><ul><li>Data is lost when the machine is powered off </li></ul></ul>6.2 Output Devices
  35. 35. 6.2.2 Display Devices (3) <ul><li>Data projector </li></ul><ul><ul><li>uses strong light beams to project images on a screen </li></ul></ul><ul><ul><li>Commonly used in classrooms to facilitate presentation. </li></ul></ul><ul><li>Data projectors are of two types: </li></ul><ul><ul><li>Liquid Crystal Display (LCD) projector </li></ul></ul><ul><ul><li>Digital Light Processing (DLP) projector </li></ul></ul><ul><ul><ul><li>uses tiny mirrors to reflect light, </li></ul></ul></ul><ul><ul><ul><li>giving brighter, more colourful images </li></ul></ul></ul><ul><ul><ul><li>and usually more durable </li></ul></ul></ul>6.2 Output Devices
  36. 36. 6.2.3 Printers (1) <ul><li>Printer </li></ul><ul><ul><li>Printing texts and graphics on paper or other physical medium , e.g. transparency film </li></ul></ul><ul><ul><li>Hardcopy </li></ul></ul><ul><ul><ul><li>exists physically </li></ul></ul></ul><ul><ul><ul><li>more permanent than softcopy </li></ul></ul></ul><ul><li>Printers can be divided into two types: </li></ul><ul><ul><li>Impact printers </li></ul></ul><ul><ul><li>Non-impact printers </li></ul></ul>6.2 Output Devices
  37. 37. 6.2.3 Printers (2) <ul><li>Printers can be divided into two types: </li></ul><ul><ul><li>Impact printers </li></ul></ul><ul><li>1 Dot Matrix Printer </li></ul><ul><ul><li>Non-impact printers </li></ul></ul><ul><li>2 Inkjet Printer </li></ul><ul><li>3 Laser Printer </li></ul><ul><li>4 Thermal Printer </li></ul><ul><li>5 Plotter/Large Format Printer </li></ul>6.2 Output Devices
  38. 38. Dot-matrix Printer <ul><li>Dot-matrix printer </li></ul><ul><ul><li>Typical impact printer </li></ul></ul><ul><ul><li>Characters are formed by dots: </li></ul></ul><ul><ul><ul><li>A matrix of pins strike an inked ribbon against the paper. </li></ul></ul></ul><ul><ul><li>Suitable for several layered paper </li></ul></ul><ul><ul><li>Use continuous-form paper with holes on both sides </li></ul></ul><ul><li>Disadvantages </li></ul><ul><ul><li>Slow and Noisy </li></ul></ul>6.2.3 Printer
  39. 39. Ink-jet Printer <ul><li>Ink-jet printer </li></ul><ul><ul><li>Non-impact printer </li></ul></ul><ul><ul><li>Spraying tiny ink drops onto a page </li></ul></ul><ul><ul><li>High quality and low price </li></ul></ul><ul><li>Disadvantages: </li></ul><ul><ul><li>1. The ink is soluble </li></ul></ul><ul><ul><li>2. Need to wait until the ink is dried completely. </li></ul></ul><ul><ul><li>3. Ink left behind will dry out and block the nozzle </li></ul></ul><ul><ul><li>4. High running cost (Ink is expensive ) </li></ul></ul>6.2.3 Printer
  40. 40. 激光打印機 <ul><li>Laser Printers </li></ul><ul><ul><li>Non-impact printer </li></ul></ul><ul><ul><li>Using laser beam to create images onto a drum </li></ul></ul><ul><ul><li>Similar to photocopying machine </li></ul></ul><ul><ul><li>Expensive, but </li></ul></ul><ul><ul><li>Fast, high-quality and low running cost </li></ul></ul><ul><li>Colour laser printer </li></ul><ul><ul><li>Mixing toners of several colours to produce many different colours </li></ul></ul>6.2.3 Printer
  41. 41. Thermal Printers <ul><li>Thermal printers are of three types: </li></ul><ul><ul><li>Direct thermal printer </li></ul></ul><ul><ul><ul><li>Direct thermal printer produces images as a </li></ul></ul></ul><ul><ul><ul><li>Heating a heat-sensitive paper </li></ul></ul></ul><ul><ul><ul><li>Used in supermarkets for price label </li></ul></ul></ul><ul><ul><ul><li>Will never run out of ink </li></ul></ul></ul><ul><ul><li>Thermal wax transfer printer </li></ul></ul><ul><ul><li>Dye sublimation printer. </li></ul></ul><ul><li>Thermal printers are not very popular </li></ul><ul><ul><li>Consumables (the wax-cartridges and the dyed ribbons) are quite expensive </li></ul></ul>6.2.3 Printer
  42. 42. Plotters/Large-format printers <ul><li>Pen plotter </li></ul><ul><ul><li>Consists of several colour pens </li></ul></ul><ul><ul><li>The pens move up and down as the paper rolls </li></ul></ul><ul><ul><li>Images are drawn by a pen plotter on a paper </li></ul></ul><ul><ul><li>Mainly used in blueprints, maps and circuit </li></ul></ul><ul><li>Large-format printer </li></ul><ul><ul><li>Larger ink-jet printer </li></ul></ul><ul><ul><li>Handle paper with widths up to 60 inches </li></ul></ul><ul><ul><li>Used in producing posters, signs and large drawings </li></ul></ul>6.2.3 Printer
  43. 43. 6.2.3 Speaker and Headsets <ul><li>Audio output device </li></ul><ul><ul><li>Enables output from a computer to be heard </li></ul></ul><ul><ul><li>The two commonly used audio output devices </li></ul></ul><ul><ul><ul><li>speakers </li></ul></ul></ul><ul><ul><ul><li>headsets </li></ul></ul></ul><ul><ul><li>Both are connected to the sound card </li></ul></ul>6.2 Output Devices