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[ The PC Guide | Systems and Components Reference Guide | Motherboard and System Devices | System Resources | Interrupts (IRQs) | IRQ Details By Number ]


IRQ Number: 12

16-Bit Priority: 7

Bus Line: 16-bit only

Typical Default Use: PS/2 mouse.

Other Common Uses: Network cards, sound cards, SCSI host adapters, VGA video cards, tertiary IDE channel, PCI devices.

Description: On machines that use a PS/2 mouse, this is the IRQ reserved for its use. Using a PS/2 mouse frees up the COM1 serial port and the interrupt it uses (IRQ4) for other devices. Normally this is a good trade since free IRQs with numbers below 8 are harder to find than ones above 8. If a PS/2 mouse is not used, IRQ12 is a good choice for use by other devices such as network cards.

Conflicts: There are some potential problems here. Watch out for PCI cards that can sometimes be assigned this line by the system BIOS. This can be changed in some cases using the BIOS setup parameters that assign IRQs to PCI devices. If you are using a PS/2 mouse you need to make sure no other devices use IRQ12.

Next: IRQ13

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