On 30/08/2017 05:29, Douglas Taylor via cctalk wrote:
I'll send along a picture of the rear of the back plane. I'm getting
the impression I can't do what I want with the old cpu cards, M7270
and M7264.
I had really hoped to be able to put together a simple system to
demonstrate the differences in processing power between the 11/2 cpu,
the 11/23 and the 11/73.
They are all dual width cards and it would have been simple to swap
them out. I think to do it I would need 2 boxes, one with a 16 bit
backplane and the other with a 22 bit backplane.
I don't see why you couldn't do what you want with the BA11-M and a
little work, *providing* the Emulex UC07 controller works in an LSI-1103
system - and the manual (on Bitsavers) suggests it should. Section
1.6.3 says "The UC07/08 is compatible with the Q-Bus used on all LSI-11
... series computers."
First, you'd need to undo any backplane upgrade that made it 22-bit
instead of 18-bit. BTW, there's no such thing as a 16-bit backplane,
only 18-bit and 22-bit. BDAL17/18 are always bussed, to allow for the
use of parity, even in 16-bit-CPU systems such as an 11/03.
The only reason you need to do this is that the KD11-H and KD11-F
processors put other signals on those lines, which the Emulex (and other
22-bit devices) won't like and will interfere with.
The soldering you mentioned is almost certainly the extra four bus lines
for the upgrade. It will be on both the B and D fingers of the
backplane, because it's a serpentine backplane with Q-Bus on both sides.
Look for wired connections between BC1, BD1, BE1, BF1 and between DC1,
DD1, DE1, DF1. Check there no other extra connections; sometimes people
added connections for other signals - for example I have a backplane
with the SRUN signal on extra slots for diagnostics and faultfinding.
Also check you don't have an H9270-Q, which is inherently 22-bit,
instead of an H9270. I've never seen one, but presumably they exist.
See http://www.dunnington.info/public/PDP-11/QBus_chassis for a little
more information.
Next you'd need some sort of bootstrap. What's in the custom EPROMs on
you MXV11-AC might do. Or might not, depending on whether it uses any
11/23 (KDF-11) specific instructions or diagnostics, and includes an
MSCP bootstrap. The autoboot feature on the UC07 might do instead. Or
might not. You'd have to experiment.
If you do keep the MXV11-AC, you've already got 32KB of memory that
works with any of your 11/03, 11/23, or 11/73 processors, and you have
two DLV11-compatible serial ports. In fact the serial ports are
virtually identical to half of a DLV11-J. Since RT11 rarely has any use
for more than two, you probably don't need any more.
If you keep the MXV11-AC and re-enable the memory, you only want another
32KB, and maybe not even that. I can't remember if RT11 5.3 will run in
32KB; it probably will, and I'm sure it would if suitably SYSGENned. I
do remember RT11 5.6 either didn't or didn't unless it was seriously
pared down. Don't use anything older than 5.3 because there are bugs in
the MSCP drivers that prevent it working with just about anything other
than RQDX1/2 interfaces.
Or you could probably use the MSV11-P. It works in 18-bit systems, and
should still work in a 16-bit (CPU) system, but obviously you'd only be
using the bottom 64KB. If you want "period" memory to match the 11/03,
you could find an MSV11-DC or -DD to use instead. The -DC has 32KB to
supplement your MXV11-AC; the -DD has 64KB. The -EC and ED versions are
the same boards but with parity circuitry added, which makes them less
common and more expensive, but they'd also do what you want.
Hope this helps...
--
Pete
Pete Turnbull
