Output devices

1
Output devices

• MONITOR
• PRINTER
• MODEM (COMMUNICATION DEVICE)

2
Monitor VDUs

• Computer monitors may be referred to as
  terminals, screens, displays or video display
  units (VDUs), but most people just call them
  monitors.
• A colour monitor operates much like a
  high-resolution TV screen, and uses the same
  basic components. An electron gun sends out a
  beam that excites pixels on the screen, making
  them light up. Instead of an antenna to pick up
  a TV signal, the graphics card inside your
  computer generates the image sent to the electron
  gun in your monitor.
• Each pixel on any colour monitor has three
  phosphors, which are red, green and blue (black
  is created when the phosphors are not
  illuminated). When the phosphors are all
  illuminated in different intensities they create
  the different colours displayed on the monitor. 

3
Ink / Bubble Jet Printers

• While the technology is vastly different for
  inkjet and bubble jet printers, both do basically
  the same thing - force tiny droplets of ink out
  of a nozzle and onto the paper. All models made
  in the last five years have a very high quality
  capable of producing realistic photo quality
• Most new Inkjet and bubble jet printers can use
  either black ink or colour ink cartridges.
  Whether you choose an Inkjet or a bubble jet
  printer is up to your personal preference and the
  size of your budget.
• The speed of inkjet and bubble jet printers is
  measured in pages per minute (ppm). Most have
  variable speeds for economy printing (about 3
  ppm), normal printing (about 2 ppm) and
  presentation quality printing (about 1 ppm).

4
Laser Printer

• If you are working in an office, the printer you
  will most likely use is a laser printer.
• Have a very high resolution, measured in dots per
  inch, and are excellent for printing black and
  white graphics and photos.
• Work about the same way as a photocopier. A
  toner cartridge lays down drops of toner onto the
  paper, and then the paper passes through heated
  rollers, which melt the toner and fuse it onto
  the page.
• Part of the reason laser printers are so
  expensive is that most have computer cards and
  RAM inside them which process and stores the data
  received from your PC.
• The quality of a laser printer is measured in
  dots per inch (dpi), with a basic printer
  starting at 300 dpi. To understand this concept,
  picture a box exactly 1 -inch square. Using a
  grid, divide the box into 300 rows horizontally
  and 300 columns vertically, and you will have 90
  000 tiny squares in the box. A 300-dpi printer
  can place a dot in every one of those squares.

5
Modems

• Acronym for MOdulator- DEModulator. A modem is a
  device or program that enables a computer to
  transmit data over telephone lines. Computer
  information is stored digitally, whereas
  information transmitted over telephone lines is
  transmitted in the form of analog (SIN) waves. A
  modem converts between these two forms.
• While the modem interfaces are standardized, a
  number of different protocols for formatting data
  to be transmitted over telephone lines exist.
  Most modems have built-in support for the more
  common protocols -- at slow data transmission
  speeds at least, most modems can communicate with
  each other. At high transmission speeds, however,
  the protocols are less standardized.
• bps How fast the modem can transmit and receive
  data. At slow rates, modems are measured in terms
  of baud rates. The slowest rate is 300 baud
  (about 25 cps). At higher speeds, modems are
  measured in terms of bits per second (bps). The
  fastest modems run at 57,600 bps, although they
  can achieve even higher data transfer rates by
  compressing the data