Digital Equipment PRIORIS ZX 6000 MP SERIES, User Manual

Page: 133 / 215

Installing Expansion Boards
8-8
Identifying PCI Devices in the SCU
The SCU automatically scans for PCI devices and assigns resources to
them. PCI devices appear in the SCU as either assigned to a slot, or as
embedded devices.
If a PCI expansion board uses one or more interrupts, but none of the
interrupts are shared, then the SCU will contain an entry for each interrupt
used by that PCI expansion board. As an example, the Adaptec 3940W
SCSI controller has a PCI-to-PCI bridge chip with two devices behind it,
each requiring an interrupt. If the expansion board were installed in PCI
Slot 1, the entry in the SCU might look similar to this:
•
PCI 1 PCI SCSI Controller IRQ15
•
PCI 1 PCI SCSI Controller IRQ14
If a PCI expansion board uses one or more interrupts, but the interrupts
are shared, then the SCU will display an entry for an interrupt in that slot,
and the remaining devices that share that interrupt will be shown as
“embedded” devices. Consider the Adaptec 3985 SCSI controller. This
controller has a PCI-to-PCI bridge chip with three devices sharing one
interrupt and the fourth device using a second interrupt. If this expansion
board were installed in PCI Slot 4, the entry in the SCU might look similar
to this:
•
PCI 4 PCI SCSI Controller IRQ10
•
PCI 4 PCI Memory Controller IRQ2(9)
•
Embedded PCI SCSI Controller
•
Embedded PCI SCSI Controller
In this case, the two interrupts are shown, with devices sharing the
interrupt shown as embedded devices.
Onboard devices always appear as embedded devices. The onboard VGA
controller, as an example, would appear as:
•
Embedded VGA