Plessy core memory

Chris Zach cz at
Sun Jan 9 20:26:11 CST 2022

Hm. So the DD11-B backplane does not appear to be SPC/MUD. Instead it 
seems to handle 4 SPC devices along with a DF11 "communication line 
adapter" in the middle AB slots.


That brings up an interesting question: How did this system ever work in 
the first place? I know I ran it with two of these Plessy cards and a 
RX01 controller but now that I look at it that would be impossible as 
both were hex cards and both could never fit in a 4 slot backplane with 
enough space for a quad spc

Maybe it did only run with 16kw of memory. Or maybe I had a 9 slot 
backplane in there, but I don't remember getting rid of one.


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