Pci To Isa Bus Interrupt Mapping; Cable Routing And Pinouts - Intergraph InterServe 80 SL System Reference Manual

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PCI to ISA Bus Interrupt Mapping

The ISA bridge provides the sixteen conventional ISA interrupts, plus four interrupt request
pins for PCI peripheral interrupts (PIRQ0 through PIRQ3). For PC-AT architecture
compatibility reasons, the PCI interrupts are routed to the ISA interrupts within the ISA
bridge. The assertion of a PCI interrupt concludes in an ISA interrupt being asserted. Bit 7
of each PCI interrupt register enables (Low) or disables (High) the routing of the PCI
interrupt to an ISA interrupt. The lowest four bits (3:0) of each PCI interrupt register
determines to which ISA interrupt the PCI interrupt is routed. You can map the PCI
interrupts to the following ISA interrupts: IRQ 5, 10, 11, 15. You can also map to IRQ 3, 4,
7, 12, and 14, but other devices are disabled if you do so.
Each PCI slot has four available interrupt lines: INT A, INT B, INT C, and INT D. These
are connected to the PCI interrupts, PIRQ0 through PIRQ3 as shown below:
Interrupt
Line
INT A
INT B
INT C
INT D

Cable Routing and Pinouts

The following tables show cable routing from the system board connectors to the various
devices in the system, and includes the pinouts of each cable.
System Board Cable Routing
From
J7
J8
J9
J10
J28 (1, 2)
J28 (15, 16)
J28 (18, 20)
J28 (24, 27)
J34
Top PCI Center Top
Slot PCI Slot
PIRQ0 PIRQ1
PIRQ1 PIRQ2
PIRQ2 PIRQ3
PIRQ3 PIRQ0
Board Connector
Secondary Controller
Primary Controller
Floppy
Input HDD
Power
Disk LED
HDD LED
Speaker
Intrusion
Center PCI Center Bottom
Slot PCI Slot
PIRQ2 PIRQ3
PIRQ3 PIRQ0
PIRQ0 PIRQ1
PIRQ1 PIRQ2
Cable To
MCBL121A Optional EIDE dirve
MCBL121A CD-ROM drive
MCBL194A Floppy drive
MCBL064A SCSI Controller or RAID
MCBL128A Standby switch
MCBL130A Disk activity LED (green)
MCBL129A Hard drive LED (green)
MCBLW66 Speaker
MCBL251A Intrusion alarm switch
Bottom
PCI Slot
PIRQ0
PIRQ1
PIRQ2
PIRQ3