Hardware Reference
In-Depth Information
accessible than any of the others. Furthermore, measurements are often more
easily taken from a board fitted in this slot position without having to resort to
the use of a
bus extender
. This point is also worth bearing in mind when fault
finding becomes necessary.
To avoid the possibility of induced noise and glitches on the supply rails,
it is usually beneficial to place boards that make large current demands or
switch rapidly, in close proximity to the power supply (e.g. in slots 6, 7, and 8
of an ISA/EISA PC system). This precaution can be instrumental in reducing
supply-borne disturbances (glitches) and can also help to improve overall system
integrity and reliability. If, however, effective decoupling precautions have been
observed, this precaution will be of minor importance.
Photo 2.4
EISA dual serial/parallel port interface card (note the use of
two mounting brackets for the external port connections)
Photo 2.5
A modern ISA card which provides 24 optically-isolated
digital inputs (photo courtesy of Arcom)
