PDP-11/05-NC with M9301?

Mattis Lind mattislind at gmail.com
Thu Mar 17 06:45:18 CDT 2016

I was thinking of using a M9301 board to get a console emulator and some
different bootstraps with the 11/05. But can I just put the M9301 in the
slot where the M930 normally goes? Slot 4 AB.

>From looking in the schematics I get that:

1. The bus grant pull ups on the M9301 is through jumpers. According to the
note they should only be installed on 11/70 systems. But the M930 do pull
these up (no jumpers here) so my guess is that these jumpers should be

2. The M930 connects much more signals to a common ground. Except for the
normal ones the M9301 uses for ground (AC2, BC2, AT1 and BT1) it also has
connected AB2, BB2, AN1, AP1, AR1, AS1, AV2, BD1, BE1, BV2 to ground.

Reading the pin assignments on a MUD slot I think that putting a M930 into
it could potentially create a lot of smoke. BV2 is -5V and AV2 is +20V if
the appropriate regulator is in the system.

M9301 goes into MUD slots. But can it go into the slot where a M930
normally sits?

My thinking is that it should work. What is your experience?


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