Looking for info on memory

[Nigel Johnson Ham]

No luck, there are no 12V traces continued to the edge connector, and
the 5VB goes to a three way jumper post where the jumper is between the
common and 5V

Besides, there are two LEDs on the board that light up, one red one green.

Thanks,

Nigel


On 2021-10-21 10:58 a.m., Chris Zach via cctalk wrote:
>
>
> On 10/21/2021 9:10 AM, Nigel Johnson Ham via cctalk wrote:
>> Thanks, but like bitsavers they are all older that the one I have.
>>
>> To be honest, I never saw anything Plessey bigger than 128kB in the
>> wild, so I have to wonder what kind of machine this board came from,
>> although it was in a pile of Qbus things that I got the J boards from.
>>
>> I'm thinking that maybe it was not sold separately, but an OEM build for
>> military etc, and perhaps it is jumpered to get power from memory - but
>> without the manual or tracing the lands I can't really tell.
>
> Wait, that could be it: If the board is jumpered to power the memory
> refresh/chips from battery then of course it wouldn't work without it.
>
> Should be easy to check: Find the battery +5 and +12 pins on the Q bus
> then use a tester meter to check from those pins to any of the jumper
> pins. If you find continuity to a jumper that is closed you might have
> identified the problem :-)