qbus module ID

From: Jerome H. Fine <jhfinexgs2_at_compsys.to>
Date: Sat Feb 5 18:45:07 2005

>Pete Turnbull wrote:

>>On Feb 5 2005, 21:17, Pete Edwards wrote:
>>Thanks everyone, looks like that's definitely an MSV11-JE, which is
>>what I was hoping.
>>Can anybody help on this one? It's an M8190 KDJ11-B, again with no
>>additional revision ID _anywhere_ on the board. Nothing even on the
>>metal strip or spacers. Looking in the field guide implies this is
>>Unibus, but I'm under the impression it came from an 11/73 - could
>>that be right, and it is qbus? (fingers crossed)
>>The part no. is 5016017-01-C1 and it has V7 roms.
>They're all the same, all QBus. Well, all the same except for speed,
>ASICs, and ROMs. The ones used in 11/84 machines go in a QBus
>backplane, with PMI memory in front and a KT84 QBus-to-Unibus converter
>Simplifying slightly, the earliest J-11 chips would not reliably run
>faster than 15MHz, and were used for 11/73s. Later ones ran at 18MHz
>and were used for 11/73s, 11/83s, and 11/84s. Some ASICs did not work
>correctly with the FPU accelerator, later ones did. Any set of ROMs
>from the series will work in any of the boards, but later ones support
>more boot devices and present different menus.
Jerome Fine replies:

Actually, there really are two different board numbers
even though the module is named as a KDJ11-Bx. The
M8190-BA,B,C has 3 versions and are all officially
call PDP-11/73 with probably most (maybe all) running
at 15 MHz and the different versions being for the FPU.

I may not remember correctly, but I seem to think that
the 83/84 board, the KDJ11-BF which is both an PDP-11/83
and the 11/84 has a different module number. There was
only one option and it ran at 18 MHz and included an FPU
chip. As far as I remember the CPU version is 9 and the
FPU version MIGHT be 5 or 7. The only board I can locate
is deep within the cables inside a BA123 and I can't get
at the board in less than 4 hours.

What is not well known (or at least not in the beginning)
was that ALL of the KDJ11-Bx boards could run with or
without PMI memory. In addition, even if PMI memory was
used, if located BELOW the CPU board, it was used as
ordinary memory, if used ABOVE the CPU board, it was
used as PMI memory. As far as I remember, I was once
told that when two PMI memory boards were used, it was
strongly advised to not mix the different capacities -
of which the MSV11-JD was 1 MByte and the MSV11-JE was
2 MBytes. MOST of the increase in speed for a PDP-11/83
was due to the PMI memory, not the shift to 18 MHz.

ALL of the above paragraph is for all Qbus systems.
I have no direct experience with the PDP-11/84 part Unibus
systems which used a DIFFERENT memory MSV11-JB,C.

Sincerely yours,

Jerome Fine
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Received on Sat Feb 05 2005 - 18:45:07 GMT

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