Intel Desktop Board D850GB Technical Product Specification
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The ICH2 has eight programmable interrupt request (PIRQ) input signals. All PCI interrupt
sources either onboard or from a PCI add-in card connect to one of these PIRQ signals. Some PCI
interrupt sources are electrically tied together on the D850GB board and therefore share the same
interrupt. Table 16 shows an example of how the PIRQ signals are routed on the D850GB board.
For example, using Table 16 as a reference, assume an add-in card using INTA is plugged into PCI
bus connector 4. In PCI bus connector 4, INTA is connected to PIRQB, which is already
connected to the SMBus. The add-in card in PCI bus connector 4 now shares interrupts with these
onboard interrupt sources.
Table 16. PCI Interrupt Routing Map
ICH2 PIRQ Signal Name
PCI Interrupt Source
PIRQF PIRQG PIRQH PIRQB Other
AGP connector INTB INTA to PIRQA
ICH2 USB controller INTD to PIRQD
SMBus controller INTB
ICH2 USB controller INTC to PIRQC
ICH2 Audio / Modem INTB
ICH2 LAN INTA to PIRQE
PCI Bus Connector 1 (J4E1) INTA INTB INTC INTD
PCI Bus Connector 2 (J4D1) INTD INTA INTB INTC
PCI Bus Connector 3 (J4C1) INTC INTD INTA INTB
PCI Bus Connector 4 (J4B1) INTB INTC INTD INTA
PCI Bus Connector 5 (J4A1) INTA INTB INTC INTD
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NOTE
The ICH2 can connect each PIRQ line internally to one of the IRQ signals (3, 4, 5, 6, 7, 9, 10, 11,
12, 14, and 15). Typically, a device that does not share a PIRQ line will have a unique interrupt.
However, in certain interrupt-constrained situations, it is possible for two or more of the PIRQ
lines to be connected to the same IRQ signal.
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