18 Jun
2013
18 Jun
'13
6:12 a.m.
On Jun 17, 2013, at 5:15 PM, Pete Turnbull <pete at dunnington.plus.com> wrote:
Beyond that, I'm not entirely sure what you're
getting at here. I
expect you know that just because a particular CPU board supports PMI
and so does a backplane, doesn't mean you have to *use* PMI. Put the
memory under the processor instead of above, and even PMI memory works
as plain old QBus memory. Nor are there any common backplanes that
don't support a KDF11 (both dual- and quad-height 11/23, 11/23+) or even
KD11-F/KD11-H (LSI-11, LSI-11/2, 11/03) -- though with KD11-F/H you want
to be careful what else might use the BDAL18-21 lines on a 22-bit backplane.
Just to be clear, though, DON'T put PMI-capable processors or memory
into a serpentine bus. The DEC literature has all kinds of warnings
about that, and while I haven't looked to see what kind of damage it
might do, it seems like a thing best avoided.
I'm sure you knew that, but for anyone else reading who doesn't, it's
worth noting.
- Dave