List of x86 hardware interrupts.

Master PIC (peripheral interface controller)

    IRQ 0 system timer (cannot be changed)
    IRQ 1 keyboard on PS/2 port (cannot be changed)
    IRQ 2 cascaded signals from IRQs 8-15 (any devices configured to use
       IRQ 2 will actually be using IRQ 9)
    IRQ 3 serial port controller for serial port 2 (0x2f8)
       (shared with serial port 4 (0x2e8), if present)
    IRQ 4 serial port controller for serial port 1 (0x3f8)
       (shared with serial port 3 (0x3e8), if present)
    IRQ 5 parallel port 3 (0x3BC) or sound card
    IRQ 6 floppy disk controller
    IRQ 7 parallel port 1 (0x378) (shared with parallel port 2 (0x278),
       if present). It is used for printers or for any parallel port if a
       printer is not present. It can also be potentially be shared with a
       secondary sound card with careful management of the port.

Slave PIC

    IRQ 8 real-time clock (RTC)
    IRQ 9 Advanced Configuration and Power Interface (ACPI)
       system control interrupt on Intel chipsets. Other chipset
       manufacturers might use another interrupt for this purpose,
       or make it available for the use of peripherals
       (any devices configured to use IRQ 2 will actually be using IRQ 9)
    IRQ 10 The Interrupt is left open for the use of peripherals
       (open interrupt/available, SCSI or NIC)
    IRQ 11 The Interrupt is left open for the use of peripherals
       (open interrupt/available, SCSI or NIC)
    IRQ 12 mouse on PS/2 port
    IRQ 13 CPU co-processor or integrated floating point unit or
       inter-processor interrupt (use depends on OS)
    IRQ 14 primary ATA channel (ATA interface usually serves hard disk drives
       and CD drives)
    IRQ 15 secondary ATA channel

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