Standard Interrupt Assignments
IRQ | Priority | Standard function |
0 | N/A | System Timer |
1 | N/A | Keyboard Controller |
2 | N/A | Programmable Interrupt |
3 * | 8 | Communications Port (COM2) |
4 * | 9 | Communications Port (COM1) |
5 * | 6 | Sound Card (sometimes LPT2) |
6 * | 11 | Floppy Disk Controller |
7 * | 7 | Printer Port (LPT1) |
8 | N/A | System CMOS/Real Time Clock |
9 * | 10 | ACPI Mode when enabled |
10 * | 3 | IRQ Holder for PCI Steering |
11 * | 2 | IRQ Holder for PCI Steering |
12 * | 4 | PS/2 Compatible Mouse Port |
13 | N/A | Numeric Data Processor |
14 * | 5 | Primary IDE Channel |
15 * | 1 | Secondary IDE Channel |
* These IRQs are usually available for ISA or PCI devices.
2-5-3 Interrupt Request Table For This Motherboard
Interrupt requests are shared as shown in the table below: |
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| INT A | INT B | INT C | INT D |
PCI slot 1 | Shared | ⎯ | ⎯ | ⎯ |
PCI slot 2 | ⎯ | Shared | ⎯ | ⎯ |
PCI slot 3 | ⎯ | ⎯ | Shared | ⎯ |
PCI slot 4 | ⎯ | ⎯ | ⎯ | Shared |
PCI slot 5 | Shared | ⎯ | ⎯ | ⎯ |
AGP slot | Shared | ⎯ | ⎯ | ⎯ |
AC97/MC97 | ⎯ | ⎯ | Shared | ⎯ |
Onboard USB | ⎯ | ⎯ | ⎯ | Shared |
Onboard USB 1 | ⎯ | ⎯ | ⎯ | Shared |
Onboard USB 2 | ⎯ | ⎯ | ⎯ | Shared |
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.
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