Computer Peripherals

Physical, Ergonomic, Safety and Environmental Requirements
In the selection and design of peripherals, a number of additional considerations have to be taken
into account, considerations which are often given scant attention in the design or selection of the
central processing unit. Usually the peripheral interacts with the user, thus defining the
environment in which the peripheral device must operate. For example, in the case of the video
display terminal, although we can package all the electronics into a very light and small unit, we
need to realise that for fast and comfortable data entry, the keyboard must be of a certain size and
the displayed characters must not be too small for easy viewing. Apart from meeting the technical
specifications the following requirements should be taken into account.
(1)
Environmental and safety requirements. The operator or the application may not been
in a clean and air-conditioned room. Power supplies may not be well regulated. There
is no computer room environment. Equipment designated to be installed in the home
will have to meet stringent standards regarding audio noise and radio frequency
interference. They also need to meet relevant safety standards.
(2)
Ergonomics. Human factors should be taken into consideration. For keyboards, it is the
tactile (touch) and/or audio feedback, the size, angle, travel and pressure of the keys
best suited for fast, accurate and comfortable typing? For printers, what is the quality
of the printed report, is it noisy in operation? In the case of displays, what is the best
colour and brightness for viewing, is a darken room needed, is there an annoying glare
from the screen, what about the amount of radiation emitted by the CRT?
(3)
Many countries have national standards and most of these are based on international
standards that have been defined and are continually modified. These standards
authorities include:
UL
Underwriters' Laboratory, US safety
FCC
Federal Communications Commission, US regulatory authority on
transmission, and radio interference
CSA
Canadian Standards Association, safety
DIN
German Standards, safety, ergonomics
www.lintech.org

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Introduction
3
ISO
International Standards Organization, safety, ergonomics, industrial standards
JIS
Japan Industrial Standards, safety, industrial standards.