E x p a n s i o n C a r d s
LS/VS 550 OWNER’S HANDBOOK 4/3
Some settings are done by jumpers and/or switches on the card and
are best done
before
installation, others are configured by running
installation software after installation. Some cards use a mixture of
both methods.
The documentation accompanying the card should tell you what is
required. Remember to check any diskettes supplied with the card
for README or other help files,
before
you start. If you are in any
doubt consult the supplier or manufacturer.
Cards often come with pre-configured or default settings. It is best
to rely on these settings as much as possible, and change them only
if they conflict with other devices.
ISA Interrupt request level (IRQ)
The interrupt request level or IRQ (the two terms are used
interchangeably) is the line over which the expansion card sends a
signal to get the attention of, or interrupt, the processor. Many of
these are reserved for components on the computer’s motherboard.
Some of these interrupts are fixed, others can be re-assigned, or
freed by disabling the component with BIOS Setup.
The following table lists the interrupts used by the computer and
shows which may be available for use by expansion cards.
IRQ
Default assignment
Available?
IRQ0
System timer
No
IRQ1
Keyboard controller
No
IRQ2
System
No
IRQ3
Serial port 2
Optionally
IRQ4
Serial port 1
Optionally
IRQ5
Audio (if fitted)
Yes
IRQ6
Diskette controller
No
IRQ7
Parallel port
Optionally
IRQ8
Real time clock
No
