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					             I/O Hardware General
   I/O Devices:
    - Input devices: translate data going into the computer to
      either ASCII or binary.
    - Output devices: take ASCII or Binary information and
      translate it into a form usable by people or other devices.
   Hardware communicates directly to the OS.
   When adding a new device usually a device driver
    must be installed.
   Device driver: software that allows the OS to
    understand the signals sent by the I/O device.
   I/O devices may require a card be inserted onto a
    mother board.
   Provides a port and local high speed data bus to the
    device.
                    Input Hardware
   Keyboard
   Pointing devices:
    - Mouse, trackball, touchpad, light pen.
    - Allow user to point at an object and perform a task, usually
      by clicking.
   Source-data entry devices:
    - Move data entry as close to the source as possible thus
      reducing human data entry error and time it takes to process
      information.
    - Scanning devices.
    - Audio input devices.
    - Video input devices.
    - Sensors.
    - Biological input devices.
                Output Hardware
   Printers:
    - Output device that prints characters, symbols, and
      graphics on paper.
    - Impact printers: produce output by using a
      mechanism to strike the paper.
       • Dot matrix: uses pins to form letters.
       • Line printers: print a whole line of characters at once.
    - Nonimpact printers: do not strike the paper.
       • Laser printer: produce output similar to the way a
         photocopy machine works.
       • Ink-jet or bubble-jet printers:
           – Spray ink on the paper to form the output image.
                   Output Hardware
   Monitors: display output on a screen for viewing.
    - Usually connected to the computer via a graphics display
      card on the motherboard.
    - Comes with its own RAM called VRAM.
    - Screens are broken down into Pixels.
    - Screen Clarity:
        • Resolution: how clear or sharp an image may be displayed on a
          screen.
            – Determined by the number of pixels, how close each pixel is (dot
              pitch) and how often the screen is refreshed (refresh rate).
    - Color:
        • Monochrome: one color displayed on black but shades of the
          color can exist.
        • Color: can display between 16 and 16.7 million colors.
                    Output Hardware
   Voice output:
    - Converts digital sounds into speech like sounds.
    - Not like a tape recorder that records your voice and replays
      it.
    - Speech coding uses an actual human voice and uses those
      words when a digital pattern is recognized.
    - Speech synthesis: uses a set of 40 basic speech sounds to
      electronically create words.
   Sound output:
    - Produces digitized sounds.
    - Requires a sound card or use of a midi-port for more
      advanced sound.
                   I/O Devices
   Perform both input and output.
   Terminals:
    - ATM, POS.
   Smart and Optical Cards:
    - Smart Cards: Used to purchase goods and
      services.
    - Optical cards Contain huge amounts of
      information using CD like optical data.
   Touch Screens:
    - Like those used in restaurants.
        Multimedia Requirements

   Fast Computer
   Lots of memory
   CD-ROM
   Sound card
   Speakers
   Good Monitor
   Device drivers

				
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