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Some expansion cards need an IRQ to operate. Generally, an IRQ must exclusively
assign to one use. In a standard design, there are 16 IRQs available but most of them
are already in use.
Standard Interrupt Assignments
IRQ
Priority
0
1
2
3 *
4 *
5 *
6
7 *
8
9 *
10 *
11 *
12 *
13
14 *
15 *
* These IRQs are usually available for ISA or PCI devices.
2-5-3 Interrupt Request Table For This Motherboard
Interrupt request are shared as shown the table below:
PCI slot1
PCI slot2
PCI slot3
Onboard LAN
Onboard VGA
AC97/MC97
Onboard USB
IMPORTANT!
2-6 Connectors, Headers
1
System Timer
2
Keyboard Controller
N/A
Programmable Interrupt
11
Communications Port (COM2)
12
Communications Port (COM1)
13
Sound Card (sometimes LPT2)
14
Floppy Disk Controller
15
Printer Port (LPT1)
3
System CMOS/Real Time Clock
4
ACPI Mode when enabled
5
IRQ Holder for PCI Steering
6
IRQ Holder for PCI Steering
7
PS/2 Compatible Mouse Port
8
Numeric Data Processor
9
Primary IDE Channel
10
Secondary IDE Channel
INT A
Not Shared
If using PCI cards on shared slots, make sure that the drivers support
"Shared IRQ" or that the cards don't need IRQ assignments. Conflicts will
arise between the two PCI groups that will make the system unstable or
cards inoperable.
Standard function
INT B
INT C
Not Shared
Shared
Shared
13
INT D
Shared
Shared
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