Noel Chiappa jnc at mercury.lcs.mit.edu
Wed May 11 14:30:44 CDT 2016

    > From: Dave Wade

    > I have recently a PDP-11 which apparently came from a VAX console.

If that's really where it came from, it's a QBUS 11/03. (And IIRC only the
780 had a PDP-11 console, although I'm not a VAX expert.)

    > It looks to me like there are two CPU's in there

Well, as Bill said, send us the 'M-numbers' (on the board handles), and we'll
tell you what you've got - but multi-CPU PDP11's basically don't exist (with
some rare exceptions), and certainly not in a VAX console. So I'm not sure
what you have there.

    > and Bus Terminator

Actually, that's the 'QBUS out' connector card; the way the PDP-11 runs the
VAX is that there's a card in the 780 CPU which is on the QBUS (there are
cables that run from the QBUS out to that card), and it allows the -11 to
totally control the 780 CPU.

    > I have done lots of searching and there doesn't seem to be a simple
    > list of what can run on it

Well, nothing that needs memory management - at least, as it sits. You could
swap out the CPU card for an 11/23 or 11/73, then you could run an OS that
needs memory management (Unix, or one of the DEC OS's that needs it - I know
nothing of the DEC OS's for the -11, someone else here will, though). And
your backplane is probably so-called Q18, limited to 256KB of memory, but
that's easy to upgrade.


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