Re(2): Re(2): [SunRescue] 4/6xx capabilities?

[jwbirdsa at picarefy.picarefy.com]

>I thought (please correct me) the SCSI passthrough on slot 7 in the x60
>cases was on the unused pins, and otherwise that was a normal slot?

   Well, yes and no. In the P2 connector, the b row is VME signals, and the
a and c rows are "user defined". Sun busses them between slots in ways that
depend on the backplane. In everything six slots and wider, it is broken up
into two or more segments. In the segment which contains the CPU, those
pins are used for the memory bus. There is usually a second multi-slot
segment which is used for other groups of board which need a private way to
communicate (e.g. framebuffer/GP/GB combinations). In the 12-plus-slot
backplanes, there are usually some slots in the middle where those pins are
not connected to anything. In the case of slot 7 on x60 and x80 backplanes,
they're used as the SCSI passthrough, but if you have no SCSI devices
hooked up, it's as "normal" as any of the other slots where rows a and c of
P2 are not connected to anything.

   --James B.