Digital Equipment Prioris XL 6000 Series, Service Maintenance Manual

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Installing Expansion Boards
7-8
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, assume a 2-channel 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 Device IRQ15
•
PCI 1 PCI SCSI Device 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 a controller that 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 3 PCI SCSI Device IRQ10
•
PCI SCSI Device
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:
•
VGA