I've updated the "NCR Diagnostics Module" archive from a few posts up with more info on the Bus(es).

Slot 1 (memory modules) has a different pinout, but the same physical connector as the expansion module slots.
Slots 7 and 7a (CPU and Diagnostics modules) carry additional signals to slots 2-6


NCR DMV- DEC Rainbow- Siemens PCD- ITT 3030-Oly People- Acorn A5000- Olivetti M20