km@mathcs.emory.edu (02/24/90)
Recently I posted a note asking for feedback on using a Sun SCSI-3 board
on a Sun 4/280. The information I had from Sun field service was that only
SCSI-2 was supported.
As many people (running SCSI-3) told me this is not the case. Our field
service rep based the advise on the following information:
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Here is a list of scsi adapters from our FE Handbook :
The 501-1045 is a Sun-2 SCSI. The 501-1236 is a Sun-3 SCSI.
Sun 3x2 Adapter Assemblies With SCSI Host Adapter
Assy # Adapter # P2 A&C SCSI Host SCSI Bus
501-1167 500-1059 yes 501-1045 external
501-1149 500-1059 yes 501-1045 internal
501-1138 500-1220 no 501-1045 external
501-1170 500-1059 yes 501-1236 internal
501-1217 500-1220 no 501-1236 external
The difference lies in if you need rows A & C connected on the P2 bus.
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I wanted an adaptor to support an external SCSI disk. The field service
rep assumed I also would want P2 A&C access, which then limited the answer
to the 501-1167 SCSI-2 board.
In practice, I think I have no need for P2 A&C, which means the SCSI-3
501-1217 would meet my need. My understanding is that P2 A&C brings the
peripheral side of the SCSI adaptor out on Suns extended VME for the
convenience of internally mounted SCSI peripherals.