PDP-11/05-NC with M9301?

william degnan billdegnan at gmail.com
Thu Mar 17 07:01:59 CDT 2016

On Thu, Mar 17, 2016 at 7:45 AM, Mattis Lind <mattislind at gmail.com> wrote:

> 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
> installed.
> 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?
> /Mattis

I am not 1/2 as knowledgeable as others here, but what comes to mind is
"backplane change", I think you'd leave the M930 where it is and on the 2nd
backplane segment install the M9301.  If you don't have a 2nd plane I'd say
you may not be able to use this.  Just my GUESS, but I am interested to
learn the correct answer.
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