Bob Armstrong
2020-06-19 00:20:30 UTC
I was reading
http://www.bitsavers.org/pdf/dec/pdp8/omnibus/EK-0PDP8-SP-001_PDP-8_Family_Configuration_Guide_Apr78.pdf
and it has some interesting configuration rules for 8/A systems. In particular, in an 8/A system the hex modules are supposed to go in the top of the backplane and the quad options at the bottom - I assume that's because only the top slots have hex wide (or really "penta wide") connectors; the bottom ones are all quad.
However it also says "there can be empty slots between hex modules but there should be no empty slots between quad modules..." That seemed odd - the OMNIBUS doesn't have any daisy chained signals, so why do empty slots matter? And why only between the quad (8/E style) modules? Did the 8/E have the same rule?
http://www.bitsavers.org/pdf/dec/pdp8/omnibus/EK-0PDP8-SP-001_PDP-8_Family_Configuration_Guide_Apr78.pdf
and it has some interesting configuration rules for 8/A systems. In particular, in an 8/A system the hex modules are supposed to go in the top of the backplane and the quad options at the bottom - I assume that's because only the top slots have hex wide (or really "penta wide") connectors; the bottom ones are all quad.
However it also says "there can be empty slots between hex modules but there should be no empty slots between quad modules..." That seemed odd - the OMNIBUS doesn't have any daisy chained signals, so why do empty slots matter? And why only between the quad (8/E style) modules? Did the 8/E have the same rule?