Further 11/40 unibus questions...

[Paul Anderson]

I always used a M930 in the 11/40 and older machines, and the M9300 in the
11/34 and newer machines. I have no way to check on the differences
now. now.  Also, there may be a trick using MOS in an 11/40.

Paul

On Mon, Jun 1, 2009 at 3:23 AM, Josh Dersch <derschjo at mail.msu.edu> wrote:

>
>
> Henk Gooijen wrote:
>
>> Date: Sun, 31 May 2009 20:39:26 -0700
>>> From: derschjo at mail.msu.edu
>>> To:
>>> Subject: Further 11/40 unibus questions...
>>>
>>> Hi all --
>>>
>>> Still having trouble with my 11/40, though it's getting closer.
>>>
>>> Currently the issue is:
>>>
>>> Without a unibus terminator installed, the machine seems to function in
>>> that I can use the front panel, toggle in and run short programs, etc.
>>>
>>> With a unibus terminator installed, the front panel is _almost_
>>> unresponsive -- I cannot examine or deposit memory or load addresses.
>>> Toggling "Run" causes a brief flicker of activity (the "Run," "Proc,"
>>> and "Bus" lights come on, the data lights flicker, and then they turn
>>> off, and the "Console" light comes back on.).
>>>
>>> Ian lent me his M9300 terminator, which caused no changes in behavior.
>>> So at least I can (probably) rule out a faulty terminator.
>>>
>>> I've verified that grant continuity cards (the tiny annoying ones) are
>>> installed in slot D of all empty Unibus slots, and that the NPG jumper
>>> is installed in all slots (since I currently have no DMA devices
>>> installed).
>>>
>>> Question: Should the NPG jumper _also_ be installed in the one SPC
>>> Unibus slot on the processor backplane? (I have a console SLU installed
>>> there currently.) This does not currently appear to be present.
>>>
>>> Before I break out the logic analyzer this evening and start debugging
>>> Unibus termination signals, I just wanted to make sure my current
>>> configuration seems sane.
>>>
>>> The boards are installed as follows:
>>>
>>> Rear:
>>>
>>> Slot 4 : Empty M9300
>>> Slot 3 : Empty
>>> Slot 2 : M7891
>>> Slot 1 : Empty | M981
>>> ---
>>> Slot 9 : M7856 | M981
>>> Slots 1-8:
>>> Front:
>>>
>>> (As mentioned before, all "empty" unibus slots have a unibus grant card
>>> + NPG jumper installed, Slot 3 has the NPG jumper installed.)
>>>
>>> Thanks once again,
>>> Josh
>>>
>>>
>>
>> The machine seems to do something (for a short while that is).
>> The only thing I can say is what I have encountered. I was triggered
>> when you wrote that you have the M7856 in slot 9 ... make sure that the
>> CA1-CB1 (NPG) pins are wired together on the backplane!  The M7856 is
>> one of the modules that does not use NPG, but also does NOT connect the
>> two pins on the module! I have that written on my webpage www.pdp-11.nl
>> (peripheral - comm - interface modules - DL11-W).
>>  I remember that I soldered a wire on the module to connect those two
>> pins,
>> as I did not want to mess with the backplane ... If you do so, make sure
>> that no flux and tin gets on the contact fingers!
>>
>> - Henk.
>>
>>
>>
> Thanks -- installed the NPG jumper for slot 9, no change.
>
> Here's a question:  The M9300 Ian lent me has three jumpers, labeled as
> follows:
>
> W1 : "Remove jumper for beginning of non processor bus termination"
> W2 : "Remove jumper for end of bus termination"
> W3 : "Remove jumper for end of processor bus termination"
>
> Currently, W1 is installed, W2 and W3 are removed.  Is this correct?
>
> I'm curious what is meant by "processor bus" vs. just "bus" in this context
> -- can someone fill me in?
>
> Thanks,
> Josh
>
>