RESOURCE CENTRE MANUAL
HEALTHLINK WORLDWIDE
(external modem). The modem links the computer to a telephone line using a
telephone cable. The same modem can be used to link more than one computer
to the same telephone line over a ‘local area network’ (LAN).
Some modems can be used to send and receive faxes (known as fax modems). A
fax modem makes it possible to communicate with people who have a fax
machine but no e-mail, as it enables messages to be sent directly from a computer
to a fax machine.
An important feature to consider when choosing a modem is speed. Faster
modems cost more to buy, but save telephone costs and on-line charges of the
Internet service provider (see Section 6.5). Modems with speeds of 56Kbs per
second are becoming standard. The speed of a connection between two modems
is limited to the speed of the slower modem. However, it is still worth buying a
faster modem, since organisations are continually up-grading their computer
equipment.
The speed is also affected by the quality of the telephone line, the computer, the
Internet service provider’s equipment, and the type of service you have
contracted. Therefore, when buying a modem, it is important to consider: the
modem speeds that the Internet service provider can support; the bandwidths
(transmission speeds) that the telephone company can support; and any local
regulations about what kind of modem may be used (in some countries,
telecommunications authorities do not allow users to connect modems to
telephone lines, or have a list of ‘approved’ modems for use in that country). The
relevant authorities or Internet service provider should be able to advise.
UPS (Uninterruptable Power Supply) This is a device that smoothes out
fluctuations in the power supply, and provides power for a short time after a
power cut. This means that work can be saved and the computer properly shut
down, preventing programs and data from becoming corrupted. This feature is
important if you live in an area that experiences electrical power surges or cuts, if
only for a second. Other factors that contribute to power fluctuations and surges
include: quality of the building’s wiring, number of electrical devices, overloaded
circuits, circuitry and wiring design.
Anti-virus software A computer virus is like a human virus – it causes damage
and is not necessarily visible. Viruses can be introduced via files on floppy disks
or e-mail attachments, or by downloading information from the Internet.
Damage caused by viruses can include loss of data, erasing the entire contents of
the hard disk, or multiplying files so that the hard disk becomes full and cannot
operate.
It is important to check regularly that there are no viruses, by using anti-virus
software. Anti-virus software needs to be updated at least every month, as new
viruses are continually appearing. It is best to take out a subscription with an
anti-virus program, so that updates are received automatically. As new viruses
SECTION 6: COMPUTERS, ELECTRONIC COMMUNICATION AND DATABASES
7