Revive 11/34

[Henk Gooijen]

AFAICR (…), the M7859 is sort of a UNIBUS device. The (front panel) console only communicates with the M7859.

The  M7859 writes/read to/from memory using the UNIBUS. Have a look at the schematics of the console.

I cannot remember whether a demux for the displays is on the console PCB, or on the M7859.

I also have a few dead M7859’s too. Of one I know that one of the two 4-bit memory chips is faulty, the others

I never investigated.



If you get 000000 on the dsipaly and when halted it shows 173066 I presume it is looping. You can use the

front panel to single step. If it loops, it will repeatedly read from a device address which is most likely the

CSR of the boot device. 173066 is an address of the boot PROMs on the M9312.

So, your 11/04 seems fine so far …

________________________________
Van: cctalk <cctalk-bounces at classiccmp.org> namens Noel Chiappa via cctalk <cctalk at classiccmp.org>
Verzonden: Saturday, December 9, 2017 5:15:18 PM
Aan: cctalk at classiccmp.org
CC: jnc at mercury.lcs.mit.edu
Onderwerp: Re: Revive 11/34

    > From: John Welch

    > Can you give me a refresher on how to tell which slots are cut? I
    > remember having to turn the chassis over and looking for a particular
    > wire

Yeah; you can use the G7273 as a 'crib', since it has the NPG jumper on it.
That jumper goes from CA1 to CB1: component side, third connector (counting
from the A connector), first and second pins (again counting from the A
connector end). A lot of the slots will still have their jumpers in, which
is how you can confirm you're looking at the right pins; look for slots
without them.


    > I also have an 11/04 that I went and drug out.

Yeah, the M7263 is the KD11-D CPU, the M7847's are MS11-E's (one of them will
be useful as a first-stage debug for the 11/34, once you've verified, in the
-11/04, that they work - the M7891 MS11-L is rare and valuable, I'd rather not
use that until everything up to that point in the -11/34 is known working -
you could try pulling the two M7847's from the -11/04 and try plugging in the
M7891, to verify that it's sort of OK).

    > I am thinking I could put a M9203/M7856 into slot 9, and find a M9312
    > for slot 3 and maybe this would fire up. Any suggestions?

As always, first pull all the boards and check the power supply (if it's been
a long time since it was last powered on, re-form the electrolytics in the
power supply first, before powering it on), then put in the _minimal_ set of
boards and get those working.


    > I added an M9302 in Slot9-AB and then moved the M7856 from the 11/34 to
    > Slot9-CDEF of the 11/04. I put a random M9312 in Slot3-AB I turned on
    > the 11/04.
    > I have six '0' digits. I push ctrl+hlt and the display shows 173066.
    > Looks like things are moving.

Yup, that's working. Now you have a working machine, you can board-swap in
from the -11/34 to check other boards out. Major, major help!!

The first thing I'd try would be the M7859, KY11-LB, from the -11/34 over
here. If it doesn't work in the -11/04 (with only that board changed), i)
you've isolated the problem, and ii) you can probably use the one from the
-11/04 to get the -11/34 working (unless there's something _else_ broken in
the -11/34 as well).

NOTE: Don't plug the good one from the -11/04 into the -11/34 - or do
anything else with the -11/34 - until you've checked the voltages in the
-11/34!!!

If the M7859, KY11-LB from the -11/34 _does_ work in the -11/04, time to keep
looking. The console itself is so dumb it's unlikely to be the problem, but
you never know; might we worth swapping. I'm having a hard time seeing what
problems in the /34 CPU, etc could cause the symptoms you're seeing - are
they still there with only the absolute minimal board set?

        Noel