Do-It-Yourself PDP-11 help!

From: Pete Turnbull <>
Date: Wed Feb 16 13:50:06 2005

On Feb 16 2005, 11:30, Gordon JC Pearce wrote:
> Vintage Computer Festival wrote:

> OK, the Baydel card has termination resistors on it - does that mean
> needs to go last in the chain?

Depends what the terminators do. If they're bus terminators, yes.
 Unless the card needs DMA, you can put it right at the end of the bus,
even if that leaves a gap between it and the previous card. That makes
it easier to slot other things in later.

> Looking at my backplane it appears that it is serpentine, rather than
> Q22/CD if I understand the documentation correctly - ie. AN2 on row 1
> goes to CM2, then CN2 goes to CM2 on row two, and so on.

That's serpentine -- but if it's not a genuine DEC backplane, check all
the way along. Not every signal, just enough to verify the order of
the slots. A few third-party ones are a bit odd.

> > I'd remove the DHV-11 to simplify things. In fact, I'd remove all
but the
> > CPU, Baydel, and memory cards, and troubleshoot with that.
> OK, I have (looking at the handles)
> M8192 M8044
> (nothing) Baydel
> I have confirmed that the M8044 passes the bus grant stuff through,
> that the backplane is sending the signals where I think it is.
> The SLU led *still* stays on. Yes, the power supplies are good.
> I did *once* get the following:
> 173026
> _at_
> from it.
> > If you've got another card with a console port to try out then that
> > be something to try.
> Haven't got one. Are they difficult/expensive to get hold of?

Not especially. Any of the DLV11 family will do, or any multifunction
(MXV11) card. The ones that are multiplexed (DHV11, DHQ11, etc) can't
be configured as a console -- except for some 3rd-party ones. For
example I have a GR 16-port DHV11 copy, on which port 1 can be
configured as a console. Is your DHV11 a genuine DEC M3104? If not,
it's just possible that it has the console, not the Baydel card (which
might have its serial port disabled or mapped to a different address).

BTW, you also ought to check the address settings on your M8044
MSV11-D. It might not be set to start at 000000. There's a set of DIP
switches on it; they should all be on, if you're using it as the lowest
banks of memory. The jumpers labelled 2-1-3 near the "B" slot fingers
might be linked 1-3 with pin 2 open. This disables bank 7, though it
shouldn't really matter for a KDJ11.

Pete						Peter Turnbull
						Network Manager
						University of York
Received on Wed Feb 16 2005 - 13:50:06 GMT

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