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2-5-2 Assigning IRQs For Expansion Card
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 slot 1
PCI slot 2
PCI slot 3
PCI slot 4
PCI slot 5
AGP slot
AC97/MC97
Onboard USB
Onboard USB 1
IMPORTANT!
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
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
Shared
Shared
Shared
12
INT D
Shared
Shared
Shared
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