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

From: Jules Richardson <julesrichardsonuk_at_yahoo.co.uk>
Date: Sun Oct 10 15:01:04 2004

On Sat, 2004-10-09 at 22:47 +0200, Gooijen H wrote:
> I checked the wiring in my 11/70.
> On this M9312, TP1 and TP2 are connected to a small push button which is
> mounted on the bottom end of the front panel. Certainly not original,
> but that is how I got this 11/70.
> >From the MK11 MOS memory box above the 11/70 is indeed a small cable
> that connects to the M9312. This cable enters the 11/70 at the rear side
> and runs, over all the boards in the space where all the flat cables are,
> to the M9312. The white/black goes on TP3, and the blank one goes on TP4.

Thanks - just what I needed! :-)

> For its function, check the 11/70 manual :-)

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...

> I do not use the battery for MOS memory backup in case of a power failure
> so I can not be of much help here.

No problem - we're not intending on using it either; I just wanted to
check that it should be OK without it. Time to do some reading this
week!

We did discover the limit of the power cabling in the museum room though
- with the 11/34, 11/44, HP T500 and a few assorted terminals running we
hit the 30A limit on the breaker and blew the power out to the room :-)
Luckily we've found a few power outlets that are on a different breaker,
so we can move some big stuff over onto that and spread the load. Still,
adding the Marconi machine, Elliott 803 and the Decsystem 570 with the
three massbus drives into the mix is going to make things interesting.
The startup sequence for everything is going to be pretty critical...

cheers

Jules
Received on Sun Oct 10 2004 - 15:01:04 BST