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									Input/Output Technology

          Chapter 7




      Systems Architecture, Fourth Edition   1
                Objectives
• Describe common concepts of text and image
  representation and display including digital
  representation of grayscale and color, bitmaps,
  and image compression techniques
• Describe the characteristics and implementation
  technology of video display devices
• List and describe the three predominant manual
  input technologies




                 Systems Architecture, Fourth Edition   2
                  Objectives
• Understand printer characteristics and
  technology
• Describe various types of optical input devices
  including mark sensors, bar code readers,
  scanners, and digital cameras
• Identify the characteristics of audio I/O devices,
  and explain how they operate



                  Systems Architecture, Fourth Edition   3
Chapter Topics




  Systems Architecture, Fourth Edition   4
   Basic Concepts of Print and
            Display
Matrix-Oriented Image Composition:
• Pixel – one part of an image. The number
  of pixels depends on the size of the
  display surface and the pixel size
• Resolution – the number of pixels
  displayed per linear measurement unit
• Dots Per Inch - measurement for
  resolution
              Systems Architecture, Fourth Edition   5
Basic Concepts of Print and
         Display




        Systems Architecture, Fourth Edition   6
Basic Concepts of Print and
         Display




        Systems Architecture, Fourth Edition   7
Basic Concepts of Print and
         Display
  A font is a collection of characters of similar style and
  appearance. Fonts are measured in point size.




                  Systems Architecture, Fourth Edition        8
Basic Concepts of Print and
         Display




        Systems Architecture, Fourth Edition   9
   Basic Concepts of Print and
            Display
Color
• The video display industry has used red,
  green and blue as primary colors (RGB).
• The printing industry generates color using
  subtractive color, the inverse of the
  primary video display colors (CMYK).



               Systems Architecture, Fourth Edition   10
Basic Concepts of Print and
         Display




        Systems Architecture, Fourth Edition   11
   Basic Concepts of Print and
            Display
Monochrome:
• Displays one of two colors
• A grayscale displays black, white and
  shades of gray




               Systems Architecture, Fourth Edition   12
   Basic Concepts of Print and
            Display
Image Storage Requirements
• Image storage requirements apply to
  images stored in primary and secondary
  storage, and to buffers used in I/O
  devices.
• Image storage requirements can be
  reduced with image compression
  techniques.
              Systems Architecture, Fourth Edition   13
 Basic Concepts of Print and
          Display

Vector – a line segment that has a
specific angle and length with respect to a
point of origin




             Systems Architecture, Fourth Edition   14
Basic Concepts of Print and
         Display




        Systems Architecture, Fourth Edition   15
Basic Concepts of Print and
         Display
      Technology Focus




         Systems Architecture, Fourth Edition   16
             Video Display
  Character-Oriented Video Display
  Terminals:
• Commonly used during 1970s and 1980s.
• Terminal – consist of an integrated
  keyboard and television screen.
• Used today primarily in systems such as
  retail checkout counters and factory floor
  environments.
               Systems Architecture, Fourth Edition   17
Video Display




 Systems Architecture, Fourth Edition   18
           Video Display


Thin Client – a hybrid device with a mix of
VDT and microcomputer characteristics.
They execute applications within an
operating environment such as Java, a
Web browser, or Windows Terminal
Services


             Systems Architecture, Fourth Edition   19
Video Display




 Systems Architecture, Fourth Edition   20
           Video Display


Video Controller – accepts the
commands and data transmitted via a bus
from the CPU and generates a TV-style
analog video signal which is transmitted to
the monitor



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Video Display




 Systems Architecture, Fourth Edition   22
             Video Display
Monitor Types:
• Cathode Ray Tube (CRT)
• Liquid Crystal Display (LCD)
• Plasma Displays




               Systems Architecture, Fourth Edition   23
Video Display




 Systems Architecture, Fourth Edition   24
                    Printers
Printer Types:
• Impact
• Laser
• Inkjet




                 Systems Architecture, Fourth Edition   25
                  Printers
Impact:
• Generate images through mechanical
  contact with ink and papers
• Character codes received by the print
  generator are transmitted as a series of
  control commands to the print head
• Characters are generated one or two
  vertical rows at a time
               Systems Architecture, Fourth Edition   26
                   Printers
Ink-Jet:
• Uses a paper movement mechanism
  similar to that of a dot matrix printer
• The print head of an ink-jet printer consists
  of an ink cartridge, a set of ink chambers
  and a set of ink nozzles
• Each ink nozzle can print a single pixel
  and nozzles are arranged in short vertical
  rows similar to those of a dot matrix printer
                Systems Architecture, Fourth Edition   27
   Printers




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                   Printers
Laser:
• Operates differently from other types of
  printers
• No print head or ink ribbon is used
• An internal image of the entire page is
  stored in an internal buffer as a bit map.
• Once filled, the buffer contents are sent to
  the print driver for generation

                Systems Architecture, Fourth Edition   29
   Printers




Systems Architecture, Fourth Edition   30
                  Printers
Plotter:
• A printer that generates line drawings on
  wide sheets or rolls of paper.
• Paper is mounted within a paper control
  mechanism that can move the paper up or
  down precisely.
• Can handle paper widths up to 60 inches.

               Systems Architecture, Fourth Edition   31
       Manual Input Devices
Input Devices:
• Keyboards
• Pointing Devices




              Systems Architecture, Fourth Edition   32
       Manual Input Devices
Keyboard Input:
• Keyboard devices translate keystrokes
  directly into electrical signals.
• A keyboard controller is used to generate
  bit stream outputs.
• The controller generates a bit stream
  output according to an internal program or
  lookup table.
               Systems Architecture, Fourth Edition   33
       Manual Input Devices
Pointing Devices:
• Mouse
• Trackball
• Joystick
• Digitizer Tablet




              Systems Architecture, Fourth Edition   34
        Manual Input Devices
Pointing Devices:
 Translates the spatial position of a pointer,
 stylus, or other selection device into
 numeric values within a system of two-
 dimensional coordinates




                Systems Architecture, Fourth Edition   35
        Manual Input Devices
Pointing Devices:
• Mouse – a pointing device that is moved
  on a flat surface such as a table, desk or
  rubber pad.
• Trackball – a mouse with the roller ball on
  the top. The roller ball is moved by the
  fingertips, thumb or palm of the hand.


               Systems Architecture, Fourth Edition   36
        Manual Input Devices
Pointing Devices:
• Joystick – used as an input device with
  computer games.
• Digitizer Tablet – uses a pen, or stylus,
  and a digitizing tablet. The tablet is
  sensitive to the placement of the stylus at
  any point on its surface.


                Systems Architecture, Fourth Edition   37
Manual Input Devices




     Systems Architecture, Fourth Edition   38
Manual Input Devices




     Systems Architecture, Fourth Edition   39
       Optical Input Devices
Mark Sensors and Bar Code Scanners:
• Mark Sensors – scans for light or dark
  marks at specific locations on a page
• The mark sensors uses preprinted bars on
  the edge of the page to establish
  reference points



              Systems Architecture, Fourth Edition   40
Optical Input Devices




     Systems Architecture, Fourth Edition   41
Optical Input Devices




     Systems Architecture, Fourth Edition   42
        Optical Input Devices
Optical character recognition (OCR):
• Combine optical scanning technology with
  hardware or software interpretation of bit
  map content
• The bit mapped representation is
  searched for patterns corresponding to
  printed characters


               Systems Architecture, Fourth Edition   43
Optical Input Devices




     Systems Architecture, Fourth Edition   44
        Audio I/O Devices
Sound generation and recognition can
be used in a number of ways
– General-purpose sound output, such as
  warnings, status indicators, and music
– General-purpose sound input, such as digital
  recording
– Voice command input



              Systems Architecture, Fourth Edition   45
          Audio I/O Devices
Speech recognition:
• The process of recognizing and
  appropriately responding to the meaning
  embedded within human speech.
• Human speech consists of individual
  sounds called phonemes.



               Systems Architecture, Fourth Edition   46
Audio I/O Devices




   Systems Architecture, Fourth Edition   47
          Audio I/O Devices
Speech Generation:
• A device that generates spoken messages
  based on textual input is called audio
  response unit
• Simple audio response units digitally store
  and play back words or word sequences



               Systems Architecture, Fourth Edition   48
                    Summary
• Manual input devices include keyboards, mice
  and other pointing devices
• A stored set of numeric pixel descriptions is
  called a bit map
• Video display terminals consist of an integrated
  keyboard and television screen
• Commonly used paper output devices include
  dot matrix printer, ink-jet printer, laser printers,
  and plotters


                   Systems Architecture, Fourth Edition   49
                  Summary
• Optical input devices include optical scanners,
  mark sensors, bar code readers, and optical
  character recognition devices
• General-purpose speech recognition systems
  can be used for command and control, or for the
  input of large amounts of textual material
• Sound cards include converters, amplifiers,
  microphone, speaker and headphone
  connectors

                 Systems Architecture, Fourth Edition   50

								
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