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Chapter 2 input and output devices
- 1. Input and Output Devices Chapter 2
- 3. Alphanumeric Keyboard • Very common, general purpose, input device that allows text (abc…), numbers (123…) and symbols (%$@...) to be entered into a computer.
- 4. Numeric Keypad • A small keyboard that only has numbers.
- 5. PIN Pad • This is a device with a numeric keypad used to enter a person’s Personal Identity Number (PIN) e.g. when paying with a credit card.
- 6. Input - Pointing Devices
- 7. Input - Pointing Devices • These devices are used to move an on-screen pointer or cursor (usually an arrow). They are commonly used with graphical user interfaces (GUIs)
- 8. Mouse • A pointing device found on most PCs. Sensors on the bottom of the mouse detect when the mouse is moved
- 9. Touchpad / Trackpad • A pointing device found on most laptops. Used instead of a mouse since it takes up less space.
- 10. Trackball / Tracker Ball • This pointing device is not moved about like a mouse, instead it has a large ball that the user spins. • Used by people with limited movement (disabled, very young)
- 11. Touch Screen • With a touch screen the user selects items on the screen by touching the surface. – Because they are so intuitive to use, and now they are getting cheaper to manufacture, touch screens will probably become the most common hardware interface for our electronic gadgets.
- 12. Graphics Tablet • A pointing device often used by designers and artists to allow natural hand movements to be input to graphics applications.
- 13. Joystick / Joypad • Used mainly for playing games.
- 14. Light Pen • A light pen is a device used as a pointing device or to ‘write’ on the screen of a computer.
- 15. Scanner
- 16. Scanner • A device that ‘scans’ images, book pages, etc.
- 17. Digital Camera • A device that captures digital photographs – The camera’s computer runs a very simple operating system (stored on ROM) and usually provides a menu-based GUI for the user.
- 18. Video Camera • A device that captures moving images, or video.
- 19. Web Cam • This is a very basic video camera used to feed live video into a computer.
- 20. Microphone • An input device that converts sound into a signal that can be fed into a computer. • An Analogue-to-Digital Convertor (ADC) is used for this (usually built into the computer’s sound card)
- 21. Input - Card Readers
- 22. Magnetic Strip Reader • Usually the data stored on this strip in the same data shown on the front of the card (e.g. the credit card number, expiry date and customer name). • A magnetic strip/stripe reader is used to read the data from the stripe.
- 23. Smart Card / 'Chip' Reader • Data can be stored in this memory and read back using a ‘chip’ reader.
- 24. Input - Reading Text / Codes
- 25. Input - Reading Text / Codes • All data could be input to a computer using a keyboard, but this would often be a slow process, and mistakes would be made. • Sometimes speed and accuracy is required...
- 26. MICR Reader • Magnetic Ink Character Recognition (MICR) is a technology that allows details from bank cheques to be read into a computer quickly and accurately.
- 27. OMR Scanner • Optical Mark Recognition (OMR) is a technology that allows the data from a multiple-choice type form to be read quickly and accurately into a computer.
- 28. OCR Scanner • Optical Character Recognition (OCR) is a software technology that can convert images of text into an actual text file that can then be edited
- 29. Barcode Reader / Scanner • A barcode is simply a numeric code represented as a series of lines.
- 30. Input - Sensors
- 31. Input - Sensors • A sensor is a device that converts a real-world property (e.g. temperature) into data that a computer can process. Sensor What it Detects Temperature Temperature Light Light / dark Pressure Pressure (e.g. someone standing on it) Moisture Dampness / dryness Water-level How full / empty a container is Movement Movement nearby Proximity How close / far something is Switch or button If something is touching / pressing it
- 32. Input - Sensors • A sensor measures a specific property data and sends a signal to the computer. – analogue signal – Converted into digital – Analogue-to-Digital Converter (ADC). • Sensors are used extensively
- 33. Input - Remote Control
- 34. Input - Remote Control • They send data signals each time a button is pressed using infrared light or radio signals. • The signals can control a computer from some distance.
- 35. Output - Audio / Visual
- 36. CRT Monitor • A cathode-ray tube (CRT) monitor is the type that has been around for years and is large and boxy. • The color accuracy and brightness of CRT monitors is excellent, and designers need to see true-to-life colors.
- 37. Flat-Screen Monitor (TFT or LCD) • TFT and LCD are two of the technologies used in flat- screen monitors: TFT is Thin-Film-Transistor, and LCD is Liquid-Crystal Display. • Another technology that may replace these is OLED, or Organic Light-Emitting Diodes.
- 38. Digital / Multimedia Projector • Used in situations when a very large viewing area is required. • A projector connects to a computer, a DVD player or a satellite receiver just like a ordinary monitor. • The image is produced inside the device and then projected out through a large lens, using a powerful light source.
- 39. Loudspeaker • If you want to hear music or sounds from your computer, you will have to attach loudspeakers. They convert electrical signals into sound waves.
- 40. Output - Printing / Plotting
- 41. Output - Printing / Plotting • If you want a physical copy of some data on paper (a ‘hardcopy’) you will need a device that can make marks on paper - a printer or a plotter
- 42. Dot Matrix Printer • A dot-matrix printer is named after the pattern (a grid or ‘matrix’) of dots used when creating the paper printout. • These dots are formed by tiny pins in the printer’s print head that hit an inked ribbon against the paper leaving marks (dots).
- 43. Dot Matrix Printer • Dot matrix printers often use continuous stationary: long, continuous strips of paper (rather than separate sheets of A4 like ink-jet and laser printers use).
- 44. Dot Matrix Printer • Dot-matrix print quality is poor, the printers are noisy – Since the pins actually hit the paper, several ‘carbon-copies’ can be printed in one go. – The print mechanism is very cheap, and the inked ribbons last for a long time.
- 45. InkJet Printer • Cheap, high-quality, full-colour printing became available during the 1980s due to the development of ink-jet printers. • It squirts tiny droplets of ink onto the surface of the paper. The droplets of ink come from tiny holes (the jets) – Perfect for photographs. – Very quiet in use – Cheap to purchase and manufacture – Ink is very expensive to buy
- 46. InkJet Printer • This is a close-up of the tiny ink dots on a page. The dots combine to form light and dark areas.
- 47. Laser Printer • Very complex devices • Expensive to buy • Very cheap to use • A single toner cartridge will often last for 5,000- 10,000 pages of printing. • Very fast printing
- 48. Plotter • Draw on the paper using a pen • More accurately • More quickly
- 49. Plotter • Plotters are only suitable for producing line drawings. • Plotters have been largely superseded by large-format ink jet printers that can produce more detailed printouts and in full-color
- 50. Output - Control Actuators
- 51. Output - Control Actuators • An actuator is a device, controlled by a computer, that can affect the real-world Actuator What it Can Do Light bulb or LED Creates light Heater Increases temperature Cooling Unit Decreases temperature Motor Spins things around Pump Pushes water / air through pipes Buzzer / Bell / Siren Creates noise
- 52. Motor • Motors can provide movement
- 53. Pumps • A pump is basically a motor attached to a device that can push water or air along pipes.
- 54. Buzzer • For example, the buzzer in a microwave oven can be switched on by the controlling computer when the food is cooked.
- 55. Lights • Lightbulbs and LEDs can by used to provide light, or to indicate something.
- 56. Heaters / Coolers • Heaters can provide heat, and coolers can cool things down.
- 57. End of Chapter 2