InputOutput Technology

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Input/Output Technology

• Chapter 7

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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

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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

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Chapter Topics
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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

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Basic Concepts of Print and Display
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Basic Concepts of Print and Display
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Basic Concepts of Print and Display
A font is a collection of characters of similar
style and appearance. Fonts are measured in
point size.
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Basic Concepts of Print and Display
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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).

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Basic Concepts of Print and Display
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Basic Concepts of Print and Display

• Monochrome
• Displays one of two colors
• A grayscale displays black, white and shades of
  gray

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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.

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Basic Concepts of Print and Display

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

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Basic Concepts of Print and Display
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Basic Concepts of Print and Display
Technology Focus
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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.

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Video Display
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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

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Video Display
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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
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Video Display

• Monitor Types
• Cathode Ray Tube (CRT)
• Liquid Crystal Display (LCD)
• Plasma Displays

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Video Display
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Printers

• Printer Types
• Impact
• Laser
• Inkjet

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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

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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

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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

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Printers
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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.

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Manual Input Devices

• Input Devices
• Keyboards
• Pointing Devices

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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.

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Manual Input Devices

• Pointing Devices
• Mouse
• Trackball
• Joystick
• Digitizer Tablet

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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

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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.

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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.

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Manual Input Devices
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Manual Input Devices
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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

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Optical Input Devices
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Optical Input Devices
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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

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Optical Input Devices
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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

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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.

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Audio I/O Devices
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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

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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

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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