PDP 11/70: MK11 memory crate, M9312 cards, and wiring...

From: Mike Cesari <mcesari_at_comcast.net>
Date: Sat Oct 16 12:48:13 2004

On Oct 10, 2004, at 2:01 PM, Jules Richardson wrote:

>
> Heh - I was staring at DEC engineering drawings for hours and it was
> giving me a headache! I need to look at all the info for the memory
> crate though as the CPU still isn't happy (the run lamp's permanently
> on
> and we can't halt the CPU or toggle any data in from the front panel).
> All cards look to be OK in the CPU though, but I suspect there may be a
> problem with the memory...
>

Jules,

The run lamp on can also indicate a power problem of one kind or
another.
Check AC and DC LOW (the purple and yellow wires). If either is low,
there
is an issue. I bet the CPU microcode address is 0200, too.

If you already haven't, terminate the unibus at the end of the backplane
in the CPU cabinet.

Mike
Received on Sat Oct 16 2004 - 12:48:13 BST