PDP 11/40 Unibus termination query...

[Josh Dersch]

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?

Thanks again,
Josh

>>
>>>
>>> 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 
>> 11/40.
>
> 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
>
>
>