Picked up a 3B2-1000 from Josh about a month ago, and I'm still poking around prior to trying to mess with it (hardware looks fine, PSU good, tape roller is jelly but that's fixed by now, hard drive died, but that's being handled). Does anyone here know much about these beasts? I have the service manual from Manx, but it doesn't say much about the architecture. Here's my big question now: I have a 3B2-1000/80 backplane (CM519B) with a 3B2-1000/70 system board (CM518B) (in a 3B2-1000/60 box, to round things out...) 3B2-1000/60 has a single ?Bus slot and several buffered ?Bus slots. 3B2-1000/80 has Pbus slots and fewer buffered ?Bus slots (Pbus takes "Processor Element" multiprocessing cards). 1000/70 might or might not have a ?Bus slot (in the 1000/60 the ?Bus takes a cache card, the cache is integrated in the /70 and /80 system boards). The service manual explains the ?Bus and the Pbus both with the blanket term of "unbuffered access to the CPU bus on the system board". Does anyone know what the difference is? At this point, I'm trying to find out what the lower slot configuration is.