IRQ |
Bus Line? |
Priority |
Typical Default Use |
Other Common Uses |
0 |
no |
1 |
System timer |
None |
1 |
no |
2 |
Keyboard controller |
None |
2 |
no (rerouted) |
n/a |
None; cascade for IRQs 8-15. Replaced by IRQ 9 |
Modems, very old (EGA) video cards, COM3 (third serial port), COM4 (fourth serial port) |
3 |
8/16-bit |
11 |
COM2 (second serial port) |
COM4 (fourth serial port), modems, sound cards, network cards, tape accelerator cards |
4 |
8/16-bit |
12 |
COM1 (first serial port) |
COM3 (third serial port), modems, sound cards, network cards, tape accelerator cards |
5 |
8/16-bit |
13 |
Sound card |
LPT2 (second parallel port), LPT3 (third parallel port), COM3 (third serial port), COM4 (fourth serial port), modems, network cards, tape accelerator cards, hard disk controller on old PC/XT |
6 |
8/16-bit |
14 |
Floppy disk controller |
Tape accelerator cards |
7 |
8/16-bit |
15 |
LPT1 (first parallel port) |
LPT2 (second parallel port), COM3 (third serial port), COM4 (fourth serial port), modems, sound cards, network cards, tape accelerator cards |
8 |
no |
3 |
Real-time clock |
None |
9 |
16-bit only |
4 |
Network cards, sound cards, SCSI host adapters, PCI devices, rerouted IRQ2 devices |
|
10 |
16-bit only |
5 |
Network cards, sound cards, SCSI host adapters, secondary IDE channel, quaternary IDE channel, PCI devices |
|
11 |
16-bit only |
6 |
Network cards, sound cards, SCSI host adapters, VGA video cards, tertiary IDE channel, quaternary IDE channel, PCI devices |
|
12 |
16-bit only |
7 |
PS/2 mouse |
Network cards, sound cards, SCSI host adapters, VGA video cards, tertiary IDE channel, PCI devices |
13 |
no |
8 |
Floating Point Unit (FPU / NPU / Math Coprocessor) |
None |
14 |
16-bit only |
9 |
Primary IDE channel |
SCSI host adapters |
15 |
16-bit only |
10 |
Secondary IDE channel |
Network cards, SCSI host adapters |