Antonio Carlini <carlini@marvin.enet.dec.com> wrote:
> The MV3100-10/20 and VS3100-30/40 do not correspond in any real way: you
> cannot convert from one to the other except by swapping the board.
   Oh sure you can, you don't even have to open up the box, just flip a
little switch on the back :-). This won't work if you are changing from
MV3100 M10/10e/20/20e to VS3100 M30/38/40/48 without putting in a GPX or
SPX video board, but will work in all other cases. I would imagine that all
NetBSD/vax users are "converting" their VS3100s to equivalent MV3100s this
way, since NetBSD/vax doesn't work with the graphical console (I think).
> (It is possible that one board was a re-design based on the other, but
> otherwise they are distinct).
   The system boards used in the MV3100 and VS3100 models in question are
different versions of the SAME BOARD. All of them use the same PCB, and
different versions are made by either putting in or omitting some
components. The VS3100 version has all components in place, while the
MV3100 version has the monochrome video and the cache memory omitted. And
the board design allowed for different versions from the very beginning, so
there was no re-design involved.
   But yes, you are right in a sense, "converting" one version into the
other by flipping the console switch doesn't give you a complete
conversion. A VS3100 converted to the corresponding MV3100 would be a
little faster than a real MV3100 because of the cache memory, and vice-
versa.
   Incidentally, the situation with the 2000s is somewhat similar. The
system boards of MV2000 and VS2000 are the same except that the VS2000
version has all components in place and the MV2000 version has the
monochrome video omitted. But cache memory is not a factor in this case,
since 2000s never have it. Also the naming is much more technically
appropriate in this case: the model number is 2000 and the system board
number is KA410 in both versions.
> The MV3100-10/20 use a KA41-A (or KA41-B in the VAXserver variant), the
> MV3100-10e/20e use a KA41-D (or KA41-E), the VS3100-30/40 use a KA42-A
> and the VS3100-38/48 use a KA42-B.
   OK, I didn't know that the MicroVAX version calls itself KA41, I have
thought that both are called KA42[0]. I'm pretty sure though that the
software-accessible system board ID is "420" in both versions. (That's why
I keep writing "KA42[0]".) Note that KA41 looks confusingly close to KA410,
and this confusion surely looks intentional. For some strange (and probably
stupid) political reason MV2000 and MV3100 were looked upon as being of the
same rank (they were nicknamed "TeamMate" and "TeamMate II", respectively),
while VS2000 and VS3100 were looked upon as being completely different
("VAXstar" and "PVAX" don't sound even close). And apparently at no point
had those asses in marketing or whatever even thought of doing The Right
Thing: putting the MV3100 and VS3100 versions on the same level.
> The MicroVAX 3100-30 and 3100-40 (same machine, different box) use a KA45
> CPU board. (I've never seen any reference to a KA44).
   MV3100 M30/40 and VS4000 VLC are twins just like the MV3100 and VS3100
models discussed above. I'm pretty sure that the software-accessible system
board ID is "440" in both versions. That's why I have thought that the
system board in MV3100 M30/40 is called KA44. You are saying that it's
actually KA45. Oh well. But no matter what you call it, it's still useless,
since neither Ultrix nor Berkeley UNIX(R) nor NetBSD will run on it. Your
(the owner's) best bet is, IMHO, to sell it to some VMSer and buy a VS3100
M38, M48, or M76, or trade directly.
   
   Sincerely,
   Michael Sokolov
   Phone: 440-449-0299
   ARPA Internet SMTP mail: mxs46@po.cwru.edu