7 Feb
2015
7 Feb
'15
10:53 a.m.
The first 25 slots are for an initial "unibus a" terminator, cpu,
floating point and memory, which, since I only have one bipolar matrix, is
an enormous waste of like ten slots (they're wired for weird voltage and
would presumably explode other boards installed there, right?).
Yes, AFAIK those memory slots are custom-wired so don't use them for
anything else.
So then there are three slots available at the end,
26, 27, 28 that are
also marked "non-standard voltage." I guess that means that putting normal
boards in there is right out, too. Anyway, the unibus out and bridge 9200
jumper that connects unibus a and unibus b are supposed to go there.
That's it for the main backplane.
You can put 3 quad-height SPC boards in there, if you don't then you have
to fit grant continuity cards. It's traditional to put the console DL11 there.
I'm going to duck after asking this, but would
it be at all feasible to
rewire the main 11/45 backplane to get rid of the weird voltages in those
bipolar slots so they'd accommodate normal boards like these?
I am sure it's _possible_ but I wouldn't do it. The 11/45 is rare enough
as it is, I wouldn't make a permanent change to the CPU backplane. And
be warned it may not be an easy change, there's a PCB under all that wire-
wrap that carried power and ground at least. If you have to change any of
that it is a _very_ big job.
Short of that, what can I do? I definitely
don't want another chassis.
Any reason not to have a 5.25" or 10.5" expansion box. From what I recall it is
possible to drop the CPU and PSUs by 5.25" fairly easily so you should be able
to make room for the former.
-tony