My
understanding is that the 3/50 is indeed some sort of VME system, as
is the 4/110, with some address related oddities. But it has been a
very long time since I booted a 3/50 up... The 3/50 I have are in their
cases, I just opened them up for the pictures.
Hmm, so the 4/110 being VME is for sure correct, I had one of those when
I was at Sun. The 3/50, I just don't think it was VME. I believe they
made a version that was a single VME board but so far as I know that was
a different beast. I could be wrong, I googled a bit and couldn't figure
it out.
What I know for sure is, unlike a 4/110, you couldn't open up the case
and shove more VME stuff in there. If the 3/50 was a VME board I'm not
sure what the point was other than, perhaps, to reuse the same part in
a small case. I can't see Andy doing that, he was super cost sensitive.
I think that the 3/50 was a "single board" VME system... and as you say
you really couldn't add anything to it. I will pull one out and get
some close up shots of the connectors and perhaps the answer can be
determined by physical inspection. I also looked at the config file for
NetBSD for the sun3 and it very much mentions vme all over the place,
but that may not have applied to the 3/50. Is it possible that just VME
connector was used for power and the like... but nothing else??