6 Apr
2013
6 Apr
'13
9:34 a.m.
allison <ajp166 at verizon.net> wrote:
I'd thought so; perhaps I'll happen across some esoteric cards that
use them, or I'll hack something custom in there.
Look uo the backplan to find out its configuration.
From my initial posting:
> It is the BA11 variety and contains a H9273 backplane, which as far as I could find
out is QQ-CD
Am I missing something here?
Also read the fine manual for the quad width 11/23 you
will find there
are jumpers/switches for use in AB/CD backplanes. Most quad width cards also conform to
that.
Also from my initial posting:
> The M8189 is a quad-width board, but with the CD
part configured
> for a serpentine backplane (the manual mentions two jumpers to be removed when using
in another
> environment to avoid shorting signals together)
Am I missing something here?
CD lines are needed for RL11 controller (two board
RL01/02 controller).
Ah, thanks. Alas I've already been promised the single
board variety of that option.
And if all else fails you can replace the backplane
with one that is
AB/AB as I've done that many times.
Thereby sacrificing the option of
integrating any CD-dependent boards I might happen across in the future. Best idea I could
think of until now would be a mixed (Q/CD - Q/Q) layout backplane, but I do not know
whether these even exist in the required 9-slot form factor. Anyway, I think I'll
treat the backplane as a given constant right now (except from probably expanding it to
Q-22, see below) and look for the "right" boards to populate it.
David Riley <fraveydank at gmail.com> wrote:
The H9273 is perfectly compatible with an 11/23 CPU;
there
is a jumper you can set for 18-bit use. Obviously, though,
turning it into a 22-bit backplane is preferable.
Fortunately, that's pretty easy.
Meh...I've been hearing that I might run into problems with some other processors
(LSI-11(/2), very early KDF11-A versions), should I ever need to use the backplane as a
test platform for one of those in the future. Is that problem the one simply worked around
with some insulating tape over the BDAL18:21 connector pads?
> The M8189 is a quad-width board, but with the CD
part configured
> for a serpentine backplane (the manual mentions two jumpers to be removed when using
in another
> environment to avoid shorting signals together), so again no "meaningful"
use of the CD lanes.
Correct. The Qbus PDP-11s only used the CD lane for
PMI
(or custom logic, if you had that).
Sounds interesting, could you elaborate?
I'd get the M8189 if you
can, because it saves you the hassle of finding boot ROM
and serial cards for the console.
Good, as it seems someone found one of these for
me.
What are these
intended for anyway (I was thinking of some sort of PMI predecessor, probably
wrong by now), and what boards do I need to take advantage of them in this machine?
For an 11/23, those lanes will just go unused. It's not
so bad, really; you have to try pretty hard to fill up 9
slots. If it's in
a box labelled 11/23, though, check to make sure someone
hasn't already performed the modification.
OK, thanks!
Arno