Regarding the boards, the non-DEC one is the 16kW board I bought installed in the '03, so I guess that works fine.

I managed to follow instructions for SimH and install and configure a V6 system. Was quite satisfying, and was quite an education. So many lessons in one session, a really good exercise.

I'm checking with Peter Schranz about whether or not his RLV12/RL02 boards can run on the '03. May be a similar issue with knobbling some of the pins, if I'm lucky.

Paul Riley

Mo: +86 186 8227 8332

On Mon, 28 Sep 2020 at 04:51, Noel Chiappa <> wrote:
    > From: Paul Riley

    > I also have a DEC 256KB board, but I doubt I could use it on the
    > '03.

Yes, DEC 256KB boards are what's called Q22, and those don't seem to work with
LSI-11's; not even CPU ODT works. I just tried a 256KB MSV11-L with an LSI-11,
and it definitely doesn't work; the MSV11-P is definitely a Q22 board, and so
probably also won't work.

What the Q22 means is that early in the lifetime of the QBUS, it only had 18
address line - so-called Q18. (Technially the LII-11 used only 16 address lines,
so it's actually Q16.) DEC latter snarfed some of the 'unused' pins, and
made them QDAL18-21. So boards that use those pins for QDAL18-21 are 'Q22'

My theory on what the problem is is that the LSI-11 uses some of those pins
for other things - I think the 'run' light, IIRC. So that confuses Q22 memory.
If one tries to use one with an LSI-11, the machine is totally dead - not even
ODT. It doesn't do any harm, though; unplug the Q22 memory, and plug in a Q18
card like an MSV11-D, and it'll be fine.

If you need memory for the LSI-11, MSV11-D boards are pretty common on eBait,
for not much. They tend to be flaky, though; sometimes they come back to life
if you leave them sit for a bit after you plug them in.

  > I believe the [memory] board is non-DEC.

Well, if it's Q22 it won't work either. Both that and the DEC board should
work in the /23, though. (If you have the part number on the memory chips, a
little arithmetic should give you the board size. 256K and up are generallly
Q22; if you have a manual for that card it might say.)

I'm still working with Mini-Unix; it's very fragile. When I got it running,
the first thing I tried to do was changle the line editing characters (since
my normal ones are burned into ROM). Alas, in stock V6, DEL is hard-wired to
be 'interrupt process', so I can't just 'stty [mumble]', I have to rebuild the
kernel to change that. Not a problem, necessarily - but I edited tty.h and
said 'cc -c tty.c', and it crashed and re-started - and roached the disk. So
I'm still trying to make progress. I might have mis-configured the simulator,
I'll see.