UK PDP11 wanted
jnc at mercury.lcs.mit.edu
Sat Apr 11 10:25:57 CDT 2015
> From: Johnny Billquist
>> Remember the jumpers I found on the 11/84 backplane? They can turn the
>> PMI section (AFAICT) into a real QBUS.
> I don't remember any jumpers.
>> 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.)
> I'll believe that when you plug the Qbus memory *before* the CPU in a
> Q/CD backplane.
But the QBUS part of _any_ QBUS backplane is not 'directional' in the same
way the CD part of the backplane in an ordinary Q/CD backplane is. (Note that
the 11/84 backplane's CD section is _not_ 'directional' the way a normal Q/CD
backplane's CD section is. See:
for more.) So for plain QBUS memory, it doesn't matter where it is in the
QBUS backplane, in relation to the CPU.
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