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Technical Reference Guide
Compaq Deskpro EN Series of Personal Computers
Desktop and Minitower Form Factors
Third Edition - September 1998
4-9
4.2.5 PCI INTERRUPT MAPPING
The PCI bus provides for four interrupt signals; INTA-, INTB-, INTC-, and INTD-. These
signals may be generated by on-board PCI devices or by devices installed in the PCI slots. In
order to minimize latency, INTA-..INTD- signal routing from the interrupt controller of the
82371south bridge to PCI slots/devices is distributed evenly as shown below:
Interrupt Cntlr. PCI Slot 1 PCI Slot 2 PCI Slot 3 PCI Slot 4 PCI Slot 5 AGP Slot USB
INTA- INTA- INTD- INTC- INTB- INTD- -- --
INTB- INTB- INTA- INTD- INTC- INTA- -- --
INTC- INTC- INTB- INTA- INTD- INTB- INTA- --
INTD- INTD- INTC- INTB- INTA- INTC- INTB- INTD-
NOTE: PCI Slot 5 on minitower only.
Interrupts generated by PCI devices can be configured to share the standard AT (IRQn) interrupt
lines. Two devices that share a single PCI interrupt must also share the corresponding AT
interrupt.
4.2.6 PCI POWER MANAGEMENT SUPPORT
This system complies with the PCI Power Management Interface Specification (rev 1.0). The PCI
Power Management Enable (PME-) signal is supported by the 440BX chipset and allows
compliant PCI and AGP peripherals to initiate the power management routine.