Allison wrote:
Jerome Fine
replies:
That would explain the situation since no one else seems
to have ever seen a pure Q22 backplane for a BA23.
It's possible, I've done it and it fits well. The Q22
18slot (M9275) is a nice backplane for non-PMI based
systems.
Jerome Fine replies:
If you want to add one more backplane to your
list, I used a 2 * 22 slot Qbus Q22 bit backplane
when I did some Y2K bug fixes for some application
programs. Specifically, this was a 22 slot backplane
with ONLY dual slots, obviously all AB. The last slot
had extra room to allow for a board of about 2" that
held a small SCSI hard drive of about 100 MBytes.
The 3rd last slot (and the 2nd last which it overlapped)
help a 3 1/2" floppy or an RX23. There was a CQD 220/TM
with special ROMs which supported the RX23 as a standard
device with removable media. By the way, the power
supply was not part of the box holding the backplane -
they (power supply and backplane) were connected by a
short 3 foot cable. I think that the ONLY DEC board
was the M8192-YB CPU.
As for one more backplane, I presume that you have the
4 * 4 slot (4 quad slots) for the VT103 which were sold
with 18 bits, but could be upgraded in the field to 22
bits. At one point, I heard that someone made the first
2 slots AB / CD and installed a uVAX-II. That was beyond
my ability, I only used an M8190-BB and a 4 MByte memory
board with a CDQ 220/TM and a DHQ11.
Those days fooling with the hardware were fun, but now
that there are emulators that can run about 100 times
the speed of a PDP-11/73, for an RT-11 software addict
like myself, the hardware has become much less important.
Sincerely yours,
Jerome Fine
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