Filter
Top Products
SYSTEM EXPANSION
3/3
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 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 Available?
IRQ0 System timer No
IRQ1 Keyboard controller No
IRQ2 System No
IRQ3 Serial port 2/Remote controller No
IRQ4 Serial port 1 Optionally
IRQ5 Audio (if fitted) Yes
IRQ6 Diskette controller No
IRQ7 Parallel port Optionally
IRQ8 Real time clock No
IRQ9 Yes
IRQ10 Yes
IRQ11 Yes
IRQ12 Mouse No
IRQ13 Coprocessor No
IRQ14 Primary ATA/IDE interface No
IRQ15 Secondary ATA/IDE interface No
With the BIOS Set-up utility IRQ4 is available if you disable serial
port1. Similarly, if you have no intention of using the parallel port,
you can disable it with the BIOS Set-up utility, completely freeing
IRQ7 for use by an expansion card. Do not disable ports unless you
have no intention of using them.