UK PDP11 wanted
pete at dunnington.plus.com
Thu Apr 9 08:48:33 CDT 2015
On 09/04/2015 13:07, Noel Chiappa wrote:
> > From: Pete Turnbull
> >> Technically, that's an 11/83 CPU...
> > Nope, it's only 15MHz ... and the MSV11-Q memory isn't PMI, so it's an
> > 11/73.
> A discussion as to whether the addition of second board can change a first
> board from an A to a B would I suspect be non-productive, so I will pass over
> that point. :-)
Are you confusing it with a KDJ11-A - a dual-height board which is
always an 11/73? But this is a KDJ11-B, quad-height, which can be
either 11/73 or 11/83. This has been discussed a few times here on
ClassicCmp, and elsewhere on DEC boards. Basically what makes the
difference is whether it's using PMI memory or QBus memory. Originally
11/73s were sold as 15MHz units in a non-PMI config. Originally 11/83s
were the same card but running at 18MHz units in a PMI config. If
you change the config to not use PMI, an 11/83 becomes an 11/73.
 there are some early revisions that wouldn't work properly in all
systems and where the DCJ11 wouldn't run at 18MHz or support a FPU
> One thing that I am curious about is the 15MHz aspect: what did DEC (if you
> recall) call a 15MHz M8190 paired with PMI memory?
An 11/83, because that's what all diagnostics, bootROMs, XXDP, RT-11
RESORC, etc would report - assuming the PMI memory is ABOVE the CPU.
But as far as I know DEC never sold them as such. All the ones sold
with 15MHz clocks were AFAIK sold with non-PMI memory. And all the ones
sold with an 18MHz crystal were sold with PMI memory as 11/83.
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