PDP 11/40 Unibus termination query...
derschjo at mail.msu.edu
Wed May 20 01:39:57 CDT 2009
Guy Sotomayor wrote:
> On May 19, 2009, at 9:55 PM, Josh Dersch wrote:
>> Guy Sotomayor wrote:
>>> On May 19, 2009, at 8:25 PM, Josh Dersch wrote:
>>> The first thing that I always do on an 11/40 is make absolutely sure
>>> that all of the jumpers on all of the CPU boards are set properly.
>>> DEC decided it wanted a lot of flexibility in 11/40 offerings. The
>>> result is a lot of jumpers spread between all of the CPU boards. If
>>> they are not *all* set properly you'll get strange behaviors.
>>> If the boards are in an unknown condition, I would configure the CPU
>>> to *not* use the MMU until you have the basic CPU running and
>>> passing some basic tests before adding in the MMU back in (yea, I
>>> know it's a pain because you have to solder/cut jumpers to change
>>> the config).
>> Hmph; just got done configuring the boards for the MMU :). Is there
>> a good reference for how the jumpers should be configured for just
>> the basic CPU set? I have the engineering drawing sets (in TIFFs...
>> anyone have these in PDF? Tiff is annoying :)), and it indicates the
>> jumpers, and _some_ of them seem to indicate a "default" position,
>> but not all, and I don't know whether these are really defaults or
>> not. I know the MMU and the Stack Limit options require jumper
>> changes, did any other options require them?
> Yes, there are jumpers for EIS & FIS too.
> Bitsavers has all of the drawings in PDF.
> I usually go off of the drawings, but I've done it enough that the
> drawings are the best way to make sure you haven't missed anything.
> I'd have to go back and lookup the drawings and compare it against
> some of the board sets I have to make sure at this point though.
> Memory is the 2nd thing to go with age...I forgot what the first one
> is. :-)
Hey, alright -- checked out my boards against the drawings again, and
the EIS jumper was removed (W1 on M7233) so I reinstalled it. Now
examine/deposit increments properly -- 2 at a time, every time :).
Now to solve the termination problem and maybe then I can get a program
to run... and then... THE WORLD!
Anyone have a spare M9312?
>>> I also don't recall at this moment the M9302, but many of the
>>> terminator boards have jumpers for the different types of pull-ups
>>> for some of the processor signals. If the pull-ups are incorrectly
>>> configured for the type of processor, the unibus can hang. Remember
>>> the unibus needs to be terminated at both ends. However, some
>>> signals are only to be terminated at one end (ie some CPUs terminate
>>> the signals themselves and others don't so the terminator at the end
>>> of the bus needs to be configured properly).
>> The M9302 does not appear to have jumpers, and it doesn't appear to
>> be of the same vintage as the 11/40 (it has a "caution" label that
>> mentions an 11/34 or 11/04...) so maybe it is incorrect for use in an
> I typically use M9312s as the terminators (since it has boot ROMs
> too). It has the appropriate jumpers. I tend to use M9302s only in
> 11/34s and 11/04s.
> TTFN - Guy
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