Multibus slot nomenclature

[roberttx]

I've been reading up on Multibus and it's beginning to feel like either I'm overlooking the obvious or I'm looking for something that doesn't exist.

The Intel spec labels the backplane connectors as J2, J3, J4, etc for P1 and J2A, J3A, J4A, etc for P2, with the lowest number furthest from the termination resistors.

But what I can't find is a scheme for identifying the slots. As in, when you're looking into a card cage and somebody is telling you which slot to stick a board into, how would they do so?

 

[daver2]

If you look at the backplane from the front (where you install the cards into) with the large (0.156” pitch connector = P1) on the bottom and the smaller (0.1” pitch connector = P2) on the top; then slot 1 is on the left hand side.

I would install the CPU card in slot 1 and the memory card in slot 2.

That’s my mental model at least...

Dave

 

[roberttx]

Thanks Dave.

So, in this drawing from the spec, Slot 1 would be connectors J5 and optionally J5A, closest to the termination resistors?

 

[daver2]

By my logic, yes.

The only 100% guaranteed way though would be to see how the serial bus priority resolution was implemented.

BPRN* on the highest priority slot will be connected to 0V and BPRO* of the lowest priority slot will be open circuit.

Dave