11/45 hack?

[Jacob Ritorto]

OK, thanks.  It seemed like too wild an idea but I thought I'd at least
ask.  Would've been cool if it was engineered to allow one to simply change
power harnesses and regulators and have a normal backplane, but I get that
that's not the case.  Not I understand why every 11/45 picture I've seen
includes a second chassis!

  This MOS / Bipolar section of the backplane is definitely not compatible
with M7891, correct?

thx
jake


On Sat, Feb 7, 2015 at 4:12 PM, Paul Anderson <useddec at gmail.com> wrote:

> 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
> >
> >
>