11/45 progress

From: Tony Duell <ard_at_p850ug1.demon.co.uk>
Date: Wed Feb 16 17:37:33 2005

> Tony wrote...
> > That sounds like an M930 terminator, which is what you want.
> Just found the fine print on the card today... M930C. That's what I have in
> the front slot, and in the "last" slot of the odd rackmount DA stuff. I
> moved it to the last slot of the MF11-L.


> I had written....
> >> I do have the KW11L. Some of my reading indicated it had something to do
> >> with the M7800? Not sure.
> Actually, I lied. On closer inspection - it's apparently a KW11P (M7228 in
> any case)

Isn't that a quad-height SPC card?

Was there anything in connector C of the frontmost slot of the CPU
backplane? Just bel;ow the terminator card? If so, make sure it stays there!

> > QWell, I didn't have that problem when I started on my 11/45. I was
> > equally unfamilliar with DEC and HP docs :-).
> Yeah... example... I know the cpu backplane includes a tiny number of unibus
> slots. I'll be damned if I can find docs that show exactly which slots (I
> know they are at the end)... how many, all quad, some quad some hex...

OK.... It's in the CPU prints somewhere (module utilisation chart, I

It's the last 3 slots (26...28), connectors C-F. All quad SPCs. There are
no hex slots (MUD or otherwise) on the 11/45 backplane.

> Still trying to find out how I determine if the memory in my /34 will work
> in my 45. It is plugged into... I think it's the 3rd slot on the /34. Non
> DEC memory. That slot is labled SPC/MUD. So what is SPC/MUD in relation to
> Unibus, hum? The term "modified unibus" doesn't mean a whole lot to me. I
> hear some /34 memory will work in the /45, some wont... unless you build a

MUD = Modified Unibus Device. What it meas is that the A/B connectors of
that slot are wired for a memory card, C-F for an SPC (Small Peripheral
Controller). Watch out, as power can end up on some strange pins of A/B..

MUD came in after the 11/45 so no slots on the CPU backplane are wired
that way.

Your memory card is almost certainly an MUD device. It will work in an
11/45, provided you use a backplane with an MUD slot. DO NOT plug it into
the memory slots on the CPU backplane, it won't work, and may let magic
smoke out.

> custom backplane or something (I think to get MUD slots)? So just which
> manual do I go to for this kind of info?

The prints for your emmory board, the PDP11 Bus handbook, prints for the
backplanes, and so on. Yes, it's confusing at first, but all new machines

> >From some of the reading I've done... it appears that even if I AM by chance
> able to find the unibus memory boards I need, I will still need to find this
> "segmentation thingy"... to allow memory over 32kw. Yay. Bet that's

You mean the MMU (Memory Management Unit).

Look at the cards at the front of your CPU backplane...

The frontmost slot contains the terminator, maybe the line time clock
(KW11-L), 2 slots for the maintenance cards (we discussed those here a
couple of months back).

Then there are 4 slots for the floating point processor. If you don't
have it, those slots are empty

Then 7 (I think) CPU cards. 2 of them carry ribbon cables to the front panel.

Then 2 slots for the MMU. If you don't have it, one of the slots is
empty, the other contains the System Address Buffer (jsut buffers and a
bit of very simple logic).

Then a quad hieght card, M8109 IIRC, which is the CPU clock.

If you have an empty slot between the CPU card set and the clock, then
you don't have the MMU (assuming nobody has been pulling cards for fun...)

> unobtainium! Oh well... it CANT be as bad as it was finding the bits and
> pieces for 2000/Access :)
> > one. I got it working... If I can do it, so can you!
> Uh.... yeah. Right.

I have been told I am clueless so often I now believe it.... Anyway, it's
just gates and flip-flops. Nothing you can't understand. And you do have
the schematics...

I wonder if _I'll_ have problems when I get my HP2100A onto the bench....

Received on Wed Feb 16 2005 - 17:37:33 GMT

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