pdp11/34 restoration : question & items sought

From: Tony Duell <ard_at_p850ug1.demon.co.uk>
Date: Wed Dec 31 17:41:41 2003

>
>
> My recently acquired 11/34 has a few missing parts :
> the boot proms of the M9301 and the M7850 parity board.
>
> It does have 16K mos memory and the full programmer panel.
>
> However, when I fire it up, I cannot halt the processor, the RUN light
> stays on.
>
> Could this be due to the missing parts ?

Not normally. This is normally due to an open grant chain (either a
missing continuity card, or a misisng wirewrap NPG jumper). Pull the
M9302 terminator (I assume you've got everything in one box, no long
Unibus cables). The machine will just about run with the bus unterminated
at the far end. If you can then halt the CPU, you've got the well-known
grant problem.

-tony
Received on Wed Dec 31 2003 - 17:41:41 GMT