Device IRQ's for older IBM AT based PC's.

0	System timer
1	Keyboard controller
2	Video graphics adapter (EGA/VGA)
3	Second serial port (COM2, COM4) or bus mouse
4	First serial port (COM1, COM3)
5	Second parallel port (LPT2, often sound card)
6	Floppy disk controller
7	First parallel port (LPT1)
8	Real time clock
9	Redirect to IRQ 2
10	Available
11	Available
12	PS/2 Mouse
13	Math coprocessor
14	Hard disk controller
15	Available (often network card or SCSI controller)