UK PDP11 wanted

Noel Chiappa jnc at
Sat Apr 11 09:47:42 CDT 2015

    > From: Johnny Billquist

    >> a _system_ with an M8190, a KTJ11 (M8191), and no PMI memory, only
    >> regular QBUS memory? (Not sure if this will work... but it should,
    >> I'll try it soon and see. 

    > Should not work, as far as I know. The CPU bus on an 11/84 is always
    > PMI.

We had a prior discussion about this. Remember the jumpers I found on the
11/84 backplane? They can turn the PMI section (AFAICT) into a real QBUS. But
that's if one wanted to use a QBUS _device_ in an 11/84 backplane (in the PMI
part, of course).

For QBUS _memory_, it should 'just work', in the same way that you can plug
an M8190 into a Q/CD backplane with some QBUS memory, and it will 'just
work'. (I.e. the M8190 will automatically do QBUS memory cycles if that's the
kind of memory that's out there.)

Now, whether the _KTJ11_ will work properly with QBUS memory instead of PMI
- no idea on that one! :-)


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