PDP-11/05-NC with M9301?

Mattis Lind mattislind at gmail.com
Thu Mar 17 15:59:56 CDT 2016

> > This means that you not have the terminator in the last slot of the bus,
> > right? Since your bus is so short it won't probably matter.
> >
> >
> Dave McGuire and I went over the system and concluded the same, basically
> it's either put it there or I can't have an RL02 drive controller because
> the NC Grant.  Dave pulled the NC Grant wire from the backplane (where the
> NC Grant card is now).

I am not sure what you mean by NC grant. On the other hand, when I think
more about it, it is a little bit weird with this setup. A MUD slot does
not carry the BG signals. And the M9312 does not terminate them unless
there is five jumpers installed. This means there will be no terminator for
the BG lines.

I am not familiar with 11/35-11/40. Is there a terminator in the other end
of the bus or is it on one of the CPU boards?

The 11/04 (and 11/34) terminate the BG signals locally at the CPU board
(since they are not terminated by the M9312 board in the MUD slot), the
11/05 does not terminate the BG signals on the CPU board it self but relies
on the M930 close to the processor.

So just maybe the BG signals are not propagating very well from the
processor back to the device since there are no terminator for them in the
far end? Just a thought.

> Anyway, I think the RAM card I have installed in this machine is
> conflicting somehow with the RL02 attempt to initialize, this is TBD, but I
> can't quite boot the machine.

I cannot really understand how the RAM card can conflict with the RL02
controller unless they are broken somehow. Fault in the address decoding
maybe? I have a QBUS memory board that responds to almost the entire range.


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