• MODEM (COMMUNICATION
Monitor – VDU’s
• 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
• 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.
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).
• 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
• 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.
• 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