OUTPUT DEVI CES

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OUTPUT DEVI CES

• FUNCTION AND APPLICATION

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Output Device

• Is any peripheral o hardware component that
  conveys information to the user.
• Output devices accepts data from the CPU and
  convert them into a form the user can understand.
  Output may be text, graphics, audio or video.

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Category of Output

• Output produced by computers can be put into two
  broad categories
• Human Readable Output Output that can be read by
  human beings.( Serving the information needs of
  people.) Eg. Output on paper/ printed data.
• Machine Readable Output Output that cannot be
  understood by human beings (it is subsequently
  used as input to the computer) Eg. Output on a
  magnetic tape or hard drive.

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Further Classification of Output

• Hard Copy
• Soft Copy.

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HARD COPY OUTPUT

• Output that can be retained for an indefinite
  period of time eg. Printed reports, plotted
  diagrams, output on tape/disk
• Hard Copy implies permanence

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SOFT COPY OUTPUT

• Output that lasts for a short period of time.
  Egs. information displayed on a monitor. Speech
  from a speaker

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Examples of output devices

• Printer
• Impact Printer
• Dot Matrix printer
• Daisy Wheel printer
• Line Pritner
• Non Impact Printer
• Inkjet printer
• Laser printer
• Thermal printer
• Photographic printer
• Graph Plotter
• Drum Plotter
• Flat Bed Plotter
• Visual Display Unit
• Liquid Crystal Display (LCD)
• Cathode Ray Tube (CRT)
• Touch Screen
• Computer Output on Microfilm
• Speaker

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PRINTER

• Is a device used to produce permanent hard copies
  of output on a physical medium such as paper or
  transparency film.
• Printers may be IMPACT or NON IMPACT Printer.

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IMPACT PRINTERS

• Are similar to the Typewriters
• They print their character by making an
  impression on paper by striking a mechanism
  (print head) against an ink ribbon onto the paper
  (leaving the image of the character on to the
  paper). Egs. Dot-matrix, daisy wheel and line
  printer.

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NON-IMPACT PRINTER

• They are printers that uses a non-striking method
  to form an image on the paper. They use thermal,
  chemical and electronic principles to form the
  image on the paper. Egs. Inkjet, Laser, Thermal
  and Photographic printers.

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Advantages Disadvantages of Impact Printers

• Advantages
• They are cheaper than non-impact printers.
• Impact printers are ideal for printing multipart
  forms and paper because they can easily print
  through many layers of paper. This make them very
  useful for printing payment receipts in business
  organizations.
• They are fairly durable and resistant to dust and
  temperature extremes.
• Disadvantages
• They are noisy
• Their print quality is slightly lower than letter
  quality
• They are slower than non-impact printers.

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Advantages of Non-Impact printers

• Advantages
• They are faster than impact printers
• They are not noisy
• They produce good quality letter print

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ABOUT IMPACT PRINTERS
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Dot Matrix

• The printing head consist of a set of pins that
  strike the ribbon on to the paper forming a dot.
• The dots are combined to form the shape of the
  appropriate character or graphic

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Characteristics of Dot matrix Printer

• The printing quality is determined by the number
  of pins the greater the number of pins, the
  higher the printing quality.

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Dot Matrix Printer Characters
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Daisy Wheel Printer

• The print-head of the daisy-wheel printer is like
  a bicycle wheel, with each character in raised
  metal or plastic.
• The wheel is turned to line up the proper letter
  under a single hammer, which then strikes the
  back of the letter and drives it into the paper
  to leave an impression.

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Characteristics of Daisy Wheel Printer

• Produce a good letter quality print.
• Does not print graphics

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Line Printer

• It is a high speed impact printer that prints an
  entire line at a time.
• Some line printers work like dot-matrix printers
  where as others print fully formed characters
  when hammers strike band of characters.

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CXC Past paper Question

• State the name of a printer which uses a bicycle
  like print head. Explain one common use of this
  printer.
• Name a printer which is noisy when printing.
• Briefly describe how a dot matrix printer
  generate hardcopy output.
• Give the name of an impact printer which cannot
  produce graphical hardcopy.

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ABOUTNON IMPACT PRINTERS
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Inkjet Printers

• They form an impression on paper by spraying
  quick-drying ink directly onto the paper.
• The print head consist of about 64 nozzles.
• Selected jets/nozzles are used to form an
  image/character

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Characteristics/Advantage of Inkjet Printer

• They are much quieter than dot matrix printer and
  produce better quality output.
• They usually produce colour prints
• Very popular for home and small offices.
• Cheaper than laser printer

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Laser Printer

• Laser printers have a drum and a toner cartridge
  that contains a finely powdered black plastic
  (powdered ink) called Toner.
• A laser beam is used to produce an image on the
  drum. The light of the laser alters the
  electrical charge on the drum whenever it heats.
  This causes the toner to stick to the drum and
  then to the paper, leaving an impression.

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Thermal Printer

• The basic thermal printer uses pins like the dot
  matrix.
• The pins are heated electrically and pressed
  against heat-sensitive paper to leave an
  impression of the appropriate character.

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GRAPH PLOTTER

• Is a device use to plot accurate things like
  diagrams, curves, images, statistical charts etc.

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PRACTICE QUESTION

• Match EACH characteristic, listed A to J below
  with the MOST appropriate device. Write the
  Letter (A, B, etc.) to represent the
  characteristic and next to EACH letter write the
  name of the device that matches it.

• CHARACTERISTIC
• Reads in graphics data
• Used for printing architectural plans
• Used for entering text documents
• Used to move the cursor
• Reads data on bank cards or credit cards
• Used to display lines of text and graphics

DEVICE Plotter Magnetic strip reader Keyboard
Magnetic strip VDU Joystick Scanner
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PRACTICE QUESTIONS
The wide variety of input devices and media is a
major factor, which adds to the flexibility and
versatility of computer systems. The use of a (i)
device, which allows users to move around images
on the monitor by shifting of a lever on the
device, has made computer games very popular. In
supermarkets, there are (ii) devices, which allow
a cashier to key in data on sales, and this data
is automatically transmitted to a computer for
processing. There are also (iii) devices that are
capable of reading pencil marks on an examination
script thereby allowing the test to be scored
automatically. The use of (iv) devices to read in
images allows pictures and logos to be
incorporated in a document. There is also the use
of a (v) device, which allows the human finger to
choose commands from a screen. State the
technical names of EACH of the devices numbered
(i) (v) on the passage above. Please use the
numbering in the passage to identify your
answers.
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• Done by
• H. Cyrus