23 Jan
2012
23 Jan
'12
7:11 p.m.
On Jan 23, 2012, at 9:35 PM, Pete Turnbull wrote:
Wolfgang Eichberger wrote:
Nice system.
But that's not a BA23, it's a BA11-N. Standard rackmount CPU box for a PDP-11/03
or early 11/23 systems so what you have may be a box that's had a CPU upgrade (maybe
not though, 11/03s would have had RLV11 not RLV12, whereas 11/23s usually had RLV12).
It's an 18-bit backplane, which matches your 256KB memory (of which 248K is usable, 8K
being reserved for the I/O page). It's fairly easy to upgrade the backplane to
22-bit, though, by removing the card cage and soldering a few wires. Wire-wrap wire is
best for that. Your MSV11-P is 22-bit capable, as are all the other cards you listed.
I'll vouch for that. My backplane (I don't currently have a box) is an H9273; the
designers kindly left proper square wire-wrap posts coming out the back. Updating to
22-bit was a very simple operation with a manual wire-wrap tool, and everything appears to
work perfectly. If you do that, make sure you run your wires in the same serpentine
pattern as the bus! Probably easiest to do the horizontal runs first and then the
verticals to splice them together. Refer to the manual if you're not sure of the
pattern, but I seem to recall that I could see the traces (it was a few years ago).
I wouldn't recommend soldering, mainly because it'd be a huge pain getting the
iron in and it's a lot less reversible. Wire-wrapping it is well worth the time if
you have the tools and the wire.
- Dave
What
backplane do you have? For example you might have one of the DEC
backplanes below:
hi glen, a little inventory:
# 11/23 BA23 Box S/N AG07072
-in there is a H786 Rev.C PSU - after quick measurements it's clear that
this PSU needs some work
-H9273 11/03L Rev.B Backplane is installed
-Cardcage is not bent but needs some of this plastic-PCB-guides, many are
broken due to age.