11/45 hack?

Paul Anderson useddec at gmail.com
Sat Feb 7 15:12:11 CST 2015

Again, I agree with Tony. I would not hack up the cpu backplane,and put in
a BA11-KE above the 45. Assuming you have it in a H960, 6 feet tall
cabinet, I would mount it 10 1/2 above the 45 for convenience  and air flow.

That should give you all the room you'll ever need.

On Sat, Feb 7, 2015 at 12:53 PM, tony duell <ard at p850ug1.demon.co.uk> wrote:

> >
> >   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

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