Dear Antonio,
   
   I finally have the time to continue our wonderful discussion on VAX CPUs
and system boards. Thank you very much for the valuable technical
information in your postings! I appreciate it greatly, and I'm sure that
other people on this list who plan to meet so-far-unsupported VAX CPUs and
system boards on the ring do too!
   Thanks for clarifying the marketing/licensing issue of MicroVAX vs.
VAXstation vs. VAXserver for us! Now I have a complete understanding.
   You wrote:
> A KA41-B (VAXserver) is cheaper than a KA41-A (MicroVAX) and the same
> applies to the KA41-E versus KA41-D [...]
   Hmm. This applies to complete MicroVAX and VAXserver boxes, right? What
about CPUs sold by themselves. Suppose I had a 3500 and the KA650 died, or
suppose I had a 3100 and the KA41 died. I could buy a replacement CPU,
right? Would the price be different depending on the setting of the
multiuser/single-user bit in the EPROM? Extending this idea further, it
seems to me that it was possible to build one's own VAX from parts the way
people often build their IBM PC-compatibles. Think of it, one could buy
separate CPUs, disk and tape drives, controllers boards, etc., right? Sure,
these parts were intended as replacement parts or upgrades for DEC-sold
boxes, but anyone could buy them, right? The only thing that I don't know
how to get separately is the enclosure frame. But theoretically it can
break too, can't it? Maybe these were also available as replacement parts?
If they were, one could build his/her own VAX from parts, and it would be
neither a MicroVAX nor a VAXstation nor a VAXserver, nor would it have a
model number... Ideal for free OSes... It's also interesting how would the
total cost of such a MicroHAX compare with that of DEC-sold MicroVAXen,
VAXstations, and VAXservers.
   You wrote:
> (So there are two different VAXserver 3100 systems, and I don't know
> which was actaully shipped if you ordered a VAXserver 3100, I would guess
> a KA41-B but I don't know).
   It better be KA41-B/E! If it were a KA42, what would KA41-B/E be for in
the first place? Second, KA41 and KA42 are different enough to have
different technical manuals. VAXserver 3100 is covered by the same
technical manual as MicroVAX 3100, while VAXstation 3100 is covered by a
different one, proving that both MicroVAX 3100 and VAXserver 3100 use KA41,
while VAXstation 3100 uses KA42.
   Thanks for the info on SID and XSID! You wrote:
> The meaning of the various portions of the XSID varies from platform to
> platform (much as most of the SID does) so the bit in KA41 that means
> VAXserver may or may not correspond to a similar bit in the KA42 or KA650
> etc.
   KA650 and KA42/41 are certainly different enough to have completely
different XSID "bitouts". They have completely different architectures,
after all (Q-bus vs. BabyVAX). OTOH, AFAIK, KA42 and KA41 are similar
enough to be INDISTINGUISHABLE for the software except by checking the
presence of base mono video (which is a very indirect indicator and should
not be relied upon by programs trying to be robust). In this case they
better have the same XSID "bitouts".
   Regarding the console selection on KA630 and KA650, you wrote:
> I don't know whether the console *has* to have 8 & 9 shorted.
   Well, then there isn't much point in me trying to extort an answer on
this one. I'll just wait until I get the technical docs.
   You wrote:
> And since I have the uVAX 2000 Tech Manual in front of me at last
> (EK-VTTA-TM.001 BTW) I can finally say that the system module has
      ^^^^
> separate video RAM.
   Isn't it EK-VTTAA-TM? As for the video RAM, I think I know which chips
it is in. I don't have a board that's not in an assembled box, so I can't
point them out precisely, but the two chips that I'm suspecting are in the
lower-left corner of the board (if the BNC tail is in the upper-right
corner). They are big DIP chips. As for the lack of base mono video support
on one of my MV2000s, it's pretty clear to me by now that the limitation is
only in the system ROM. Apparently MV2000 and VS2000 did use different
versions of KA410 after all, although the difference is only in the system
ROM. On the other hand, it's likely that this is the case only on late
revisions (the culprit one is V2.3).
   You wrote:
> I believe that the host adapters SCSI ID is settable via the console.
   ?!?! This is the first time I hear this. How would you change the host
adapter SCSI ID on, say, KA42?
   You wrote:
> I think
> that most systems ship as ID 6 (at least mine in the lab are set to 6).
   The manuals for VS3100 M40 and DS3100 (the only pertinent ones I have so
far) both say that the host adapter SCSI ID is 6 and never even hint at any
possibility of it being different. I have also played with one of my KA42s.
It has a SCSI/SCSI mass storage controller daughterboard, and the host
adapter SCSI ID is 6 on both buses. I have looked through all console
commands, but I couldn't find anything that can change this.
   This SCSI ID of 6 seems to be so well-established that I had never
thought that it could be different on any of the related systems until I
saw that post by Thordur clearly indicating that at least one KA41 in the
world has it set to 7. That post has kept me wondering since then, and
since I currently have neither a KA41 to play with nor any MV3100 docs to
read, I'm waiting for the docs to arrive meanwhile checking if you or
anyone else has a clue.
   
   Sincerely,
   Michael Sokolov
   Phone: 440-449-0299
   ARPA Internet SMTP mail: sokolov@alpha.ces.cwru.edu