Input

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Input OutputPart II

• Bayram Güzer

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Output

• Output provides the information for the user.
• Computer systems have several kinds of outputs.
• Main output units in computer systems are screens
  and printers.

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Output

• Example Suppose that you went to a travel agency
  and asked for reservation on an flight
  connection. The travel agent will enter data and
  make few queries to find available flights and
  the results will be displayed on a screen. If
  reservation is made, then the agent can get a
  printed output for tickets, traveler's itinerary
  and the invoice.

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Computer Screen Technology

• In computer systems, screen is one of the main
  elements.
• When you enter data, it appears on the screen.
• The screen is a part of the computer monitor
  which also includes electrical components,
  monitor stand and etc
• Soft copy is the screen output because it is
  intangible and temporary
• Hard copy is produced by printer on a paper and
  it is tangible and permanent

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Common Forms of Monitors

• Cathode Ray Tube (CRT)
• Flat-Panel Screens
• Smart Displays
• Terminals

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CRT Monitors

• Display text and graphics
• Most are in color
• Some monochrome monitors are used in applications
  that have no need for color or graphics
• Uses of monochrome monitors are in business
  applications such as customer inquiry or order
  entry systems that no color is needed.
• Graphics card converts signals from the control
  unit into the image the user sees

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CRT Monitors

• Most CRT screens uses a technology which is
  called as raster scanning.
• Raster scanning is a process of sweeping
  (süpürmek) electron beams from back of the
  screen.
• The screen display has a phosphorous coating that
  glows whenever it is hit by a beam of electrons.
• But the phosphorus doesnt glow for very long, so
  the image must be refreshed often.
• If the screen is not refreshed often enough, the
  fading screen image appears to flicker (titreme).

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CRT Monitors

• Scan rate
• The frequency with which the image is refreshed
• The sufficient rate is 80 or 100 times per second
• Interlaced is another method for scanning the
  screen.
• In interlaced fashion, first the odd-numbered
  lines and then the even-numbered lines are
  scanned.
• This requires a lower refresh rate without
  producing any flickering.
• When animations appear in monitors, interlacing
  can create irritating flutter (dalgalanma)
  effect. For that reason, most screens are today
  announced as non-interlaced which means all lines
  are scanned in order.

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CRT Monitors

• A computer screen is divided into dots that is
  called as addressable because they can be
  addressed individually.
• Each dot can be illuminated individually on the
  screen.
• Each dot is potentially a picture element or a
  pixel.
• Resolution defines clarity (açiklik) of screen
• Measured in pixels (picture elements)
• The more pixels, the higher the resolution
• There are some graphics standards exist

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CRT Monitors

• Dot pitch
• It is the amount of space between dots
• If the dot pitch is smaller, the image is
  sharp-edged (keskin kenarli)
• Most computers come with built-in graphics
  compatibility.
• But if the computer doesnt have built-in
  graphics, there will be a need for graphics card
  or graphics adapter board.

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Graphic Standards

• Defines the agreement on resolutions, colors,
  other issues related to displaying graphics
• Super Video Graphics Adapter (SVGA) is most
  common standard
• Provides 800 (horizontal) x 600 (vertical) pixels
  on the display
• Other varieties of SVGA exist
• 1024 by 768
• 1280 by 1024
• 1600 by 1200
• Support 16 million colors
• The number of colors that can be displayed
  depends on amount of video memory

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Graphic Standards

• Extended Graphics Array (XGA) is a high
  resolution graphics standard designed to replace
  older standards.
• It provides more simultaneous colors
• It allows monitors to be non-interlaced.

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Flat Screen Monitors

• Liquid crystal display (LCD)
• Originally used for laptops, but making their way
  to desktop computers by becoming bigger every
  day.
• Very thin (only a few inches)
• Produce sharper text images than CRTs
• Easier on eyes than CRTs
• More expensive than CRTs

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Flat Panel Technologies

• Active-matrix
• Uses many thin-film transistors (TFT)
• Produces brighter image and can be viewed from
  wider angles
• Passive-matrix
• Uses fewer transistors
• Cheaper and uses less power
• Gas plasma
• Supports very large displays
• Has brilliant color display
• Viewable at very wide angles

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Smart Displays

• Based on flat-panel technology
• Each contains its own processor
• Wireless transmitter-receiver allows user to
  control desktop from anywhere in the house
• Idea was announced by Microsoft as Mira in 2002,
  but the project was cancelled in December 2003.

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Terminals

• A screen can be part of a terminal attached to a
  large computer.
• A terminal consists of an input device, an output
  device, and a communications link to the main
  computer.
• Smart terminals are the terminals which has some
  processing ability of their own CPU.
• Bank tellers use terminals to communicate
  directly with a central computer to determine
  bank balances and other information.

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Printers

• A printer is a device that produces information
  on paper output.
• Old printers were producing only letters and
  numbers.
• Most printers have two orientation setting which
  is portrait and the landscape.
• Portrait mode prints out on vertical side
• Landscape mode prints out on horizontal side

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Printers

• There are two ways for printing an image on
  paper.
• Impact method
• Uses some sort of physical contact with the paper
  to produce an image
• Physically strike (hit) to paper, ribbon and
  print hammer together
• Line Printers Impact printers that print entire
  line at a time is called as line printers. It is
  typically used with mainframe computers for
  printing lengthy reports.

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Printers

• There are two ways for printing an image on
  paper.
• Impact method
• Dot-matrix printers Has print head consisting of
  one or more columns of pins
• Pins form characters and images as patterns of
  dots

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Printers

• There are two ways for printing an image on
  paper.
• Nonimpact method
• Places an image on a page without physically
  touching the page.
• Major nonimpact technologies are laser and
  ink-jet printers.
• Laser printers use a light beam to help transfer
  images to paper.
• Laser printers produces high-quality output at
  very fast speeds.

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Printers

• There are two ways for printing an image on
  paper.
• Nonimpact method
• Ink-jet printers spray ink from multiple jet
  nozzles
• Can print in both black white and different
  colors.
• Print quality and speed is not matching that of a
  laser printer.
• Less expensive than laser printers but requires
  high quality paper so ink doesnt spread

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Voice Output

• Speech synthesis is the process of enabling
  machines to talk to people.
• Voice synthesizers convert data to vocalized
  sounds that is understandable to humans.
• Two approaches exist
• Synthesis by analysis - analyzes actual human
  voice, records and plays back as needed
• Synthesis by rule - uses linguistic rules to
  create artificial speech
• Used in automated telephone-based customer
  service applications
• Useful when an inquiry would be followed by a
  short reply, such as a balance inquiry, automatic
  telephone voice survey.

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References

• Capron, H. L. (2000). Computers Tools for an
  Information Age.(6th ed.). New Jersey, USA
  Prentice Hall.
• Long, L. Long, N. (2001). Computers. (8th ed.).
  New Jersey, USA Prentice Hall.
• Smart Display. (n.d.). Retrieved 01 November 2009
  from http//www.amazon.com/ViewSonic-airpanel-V150
  -Smart-Display/dp/B00007A5K0
• Smart Displays. (2008). Retrieved 01 November
  2009 from http//en.wikipedia.org/wiki/Smart_Disp
  lay