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Hardware Setup
PCI Interrupt Request Routing
The IRQ, acronym of interrupt request line and pronounced I-R-Q, are
hardware lines over which devices can send interrupt signals to the
microprocessor.
For efficient IRQ allocation, PCI slot 1 and slot 6 are designed to share
the same IRQs. To install a PCI expansion card on a PCI shared slot, you
must make sure the card’s driver supports “IRQ shared” function or
there is no need to assign an IRQ to the device.
The PCI IRQ pins are typically connected to the PCI bus INT A# ~ INT
D# pins as follows:
Order 1 Order 2 Order 3 Order 4
PCI Slot 1 INT A# INT B# INT C# INT D#
PCI Slot 2 INT B# INT C# INT D# INT A#
PCI Slot 3 INT C# INT D# INT A# INT B#
PCI Slot 4 INT D# INT A# INT B# INT C#
PCI Slot 5 INT B# INT C# INT D# INT A#
PCI Slot 6 INT C# INT D# INT A# INT B#
