Dear Thordur,
   
   Thanks for your answer! Now see that KA41 really IS a different PCB from
KA42, since it requires different back panel cutouts. Note the arrangement
of serial ports (one DB25 and 3 MMJs numbered 1, 2, and 3 with 1 being the
console) is just like on DEC-shipped MV2000s (where this arrangement is
created by a strange-looking box screwed into the DB15 and DB9 connectors
on the system unit). This further supports the idea that MV2000 and MV3100
were viewed as being of the same rank (similar nicknames, system board
numbers, and serial port arrangements).
   By the way, your picture suggests that the external SCSI connector is
Centronics-50. Is it really? Is it on the left or on the right (if you look
from the back)? I have always thought that all KA41/42 systems use those
funny reversed-gender high-density 68-pin connectors, and I have always
seen them on the left side of the back panel.
   Also the SCSI configuration display indicates that both SCSI controllers
have SCSI ID 7 assigned to themselves. Do you know why is it so? This is
standard with SCSI in general, but I have always thought that KA41/42 (the
BabyVAXen in question) and KN01 (DS2100/3100) use SCSI ID 6 for host
adapters.
   You wrote:
> This system is belived to be MV3100m20 or MV3100m20e
   The system board identifies itself as KA41-D. Thanks to Antonio Carlini,
we now know that it's the 33 MHz version and that it's a MicroVAX as
opposed to a VAXserver. These boards are used in MV3100 M10e and M20e.
Since yours is in a BA42-B enclosure (the thicker one), it fits the
characteristics of MV3100 M20e.
> I have here somewere owners manual for this system but it is very bad
> document.
   Is it the owner's manual? Could you tell me its DEC part # so that I can
ask Richard for a copy? Also would you please look in the related documents
section to see if it references some technical or maintenance manuals? I
have recently come across the owner's manual for VS3100 M40, and now I know
the part # for the VS3100 technical docs and also for the owner's manuals
for other VS3100 models, since the one I have has a cover letter that
references them. Maybe there is a similar cover letter with document
references in your manual too? I would appreciate any doc part #s for KA41
systems, since I'm beginning to learn that they are more different from
KA42s than I have thought before, and I want to know them perfectly.
> Series BA42B CPU KA41
   This is telling you that the system enclosure is BA42-B, which agrees
with the external appearance, and that the system board is KA41, which
agrees with the console display.
   
   Sincerely,
   Michael Sokolov
   Phone: 440-449-0299
   ARPA Internet SMTP mail: sokolov@alpha.ces.cwru.edu