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2-7-2 Assigning IRQs For Expansion Card
Some expansion cards need an IRQ to operate. Generally, an IRQ must be
exclusively assigned. In a standard design, there are 16 IRQs available, but
most of them might already be 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.
2-7-3 Interrupt Request Table For This Motherboard
Interrupt requests are shared as shown in the table below:
PCI slot 1
PCI slot 2
PCI slot 3
PCI slot 4
PCI slot 5
AGP slot
AC97/MC97
Onboard USB
Onboard USB 1
Onboard USB 2
IMPORTANT! 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 and will make the system unstable or
cards inoperable.
N/A
System Timer
N/A
Keyboard Controller
N/A
Programmable Interrupt
8
Communications Port (COM2)
9
Communications Port (COM1)
6
Sound Card (sometimes LPT2)
11
Floppy Disk Controller
7
Printer Port (LPT1)
N/A
System CMOS/Real Time Clock
10
ACPI Mode when enabled
3
IRQ Holder for PCI Steering
2
IRQ Holder for PCI Steering
4
PS/2 Compatible Mouse Port
N/A
Numeric Data Processor
5
Primary IDE Channel
1
Secondary IDE Channel
INT A
Shared
Shared
Shared
Standard function
INT B
INT C
Shared
Shared
Shared
16
INT D
Shared
Shared
Shared
Shared
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