Rich Alderson wrote: > On 9-track tape, in the default mode for all PDP-10 operating systems, > referred to as core-dump mode, 36 bit words are stored into 5 8-bit > frames (with logical parity) as follows: > > bits 0-7 x x x x x x x x P > bits 8-15 x x x x x x x x P > bits 16-23 x x x x x x x x P > bits 24-31 x x x x x x x x P > bits 32-35 0 0 0 0 x x x x P
I thought so too. But I had a reason to look into chapter 3 of the TM10 maintenance manual, and I saw something interesting. Apparently, the TM10 does a slight variation (or is this the canonical version?) of the core dump format. It writes the last *six* bits to the last frame, so bits 30 and 31 are actually written to two places: > bits 24-31 x x x x x x y y P > bits 32-35 0 0 y y z z z z P When reading, it inclusive-ors the overlapping bits. _______________________________________________ Simh mailing list [email protected] http://mailman.trailing-edge.com/mailman/listinfo/simh
