Mitsubishi Electric apricot ls/vs550 Owner's Handbook Manual page 25

E x p a n s i o n
ISA Interrupt request level (IRQ)
3/2 LS/VS550 OWNER'S HANDBOOK
♦
Direct memory access (DMA) channel
♦
Base input/output (I/O) port address
♦
Base memory address
The settings used by the card must be different to existing hardware
in the computer. The settings must not conflict with other cards or
a component on the motherboard.
Some settings are done by jumpers and/or switches on the card and
are best completed before installation, others are configured by
running installation software after the card has been fitted inside the
computer. Some cards use a mixture of both methods. The
documentation accompanying the card should tell you what is
required. If you are in any doubt consult the supplier or
manufacturer.
Most modern cards are supplied with default settings which are
often an industry standard. It is best to rely on these where possible.
The interrupt request level or IRQ (either term can be used) 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. While some
interrupts are fixed, others can be re-assigned.
The following table lists the interrupts used by the computer and
shows which may be available for use by expansion cards.
IRQ Default assignment
IRQ0 System timer
IRQ1 Keyboard controller
IRQ2 PIC daisy chain
IRQ3 Serial port 2
IRQ4 Serial port 1
IRQ5 Optional sound system
IRQ6 Diskette controller
IRQ7 Parallel port
Available?
No
No
No
Optionally
Optionally
Optionally
No
Optionally