IBM PC Hardware Interrupt Table (in order of priority)

% IRQ# Interrupt Function

IRQ0 8 ~timer~ (55ms intervals, 18.2 per second)

IRQ1 9 keyboard service required

IRQ2 A slave ~8259~ or EGA/VGA vertical retrace

IRQ8 70 real time clock (AT,XT286,PS50+)

IRQ9 71 software redirected to IRQ2 (AT,XT286,PS50+)

IRQ10 72 reserved (AT,XT286,PS50+)

IRQ11 73 reserved (AT,XT286,PS50+)

IRQ12 74 mouse interrupt (PS50+)

IRQ13 75 numeric coprocessor error (AT,XT286,PS50+)

IRQ14 76 fixed disk controller (AT,XT286,PS50+)

IRQ15 77 reserved (AT,XT286,PS50+)

IRQ3 B COM2 or COM4 service required, (COM3-COM8 on MCA PS/2)

IRQ4 C COM1 or COM3 service required

IRQ5 D fixed disk or data request from LPT2

IRQ6 E floppy disk service required

IRQ7 F data request from LPT1 (unreliable on IBM mono)