11/45 hack?

[Paul Anderson]

I'm pretty sure it's not.

Do you only have one G401?  strange...

On Sat, Feb 7, 2015 at 6:04 PM, Jacob Ritorto <jacob.ritorto at gmail.com>
wrote:

> 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
> > >
> > >
> >
>