On Tue, Jan 4, 2011 at 8:17 AM, Pontus <pontus at update.uu.se> wrote:
Hi all.
In order to make room for an 11/44 I'm giving away a PDP-11/23 with two RL01
drives. I have a bunch of spare Q-BUS cards for the 11/23 and I wonder if
any of them are compatible with the 11/73.
Most will be (though the RLV11 happens to require a backplane wired
with a "CD Interconnect")
So, here is what I got for the 11/23:
Memory: M7506, M8043, M8044, M8047, M8059, M8067
Checking
http://world.std.com/~mbg/pdp11-field-guide.txt, your memory
pile looks like:
M8043: DLV11 - a quad serial card (those four 40-pin DIPs are UARTs, not SRAM)
M8044: MSV11-D - if full (most are), it's an MSV11-DD, a 32Kword RAM
card - small for a large system
M8047: MXV11 - probably a 16Kword card w/SLUs - also small for a large system
M8059: MSV11-L - either -LF (64Kword) or -LK (128Kword) - medium-sized
M8067: MSV11-P - either -PF (128Kword) or -PK (256Kword) or -PL
(512Kword) - large for DEC
M7506: MSV11-M - either -MA (256Kword) or -MB (512Kword)
Your limits are 2Mword (4Mbytes) of total Qbus memory on a 22-bit
system. In my experience, few Qbus machines had more than 4 memory
boards of any size, most had 1-2 (if you needed to add more memory, it
was "more economical" to remove the older, smaller stuff and use the
same number of slots with larger capacity cards.
If I've understood the matter correctly the 11/73
can utilize 22 bits of the
Q-BUS but the 11/23 only 18 bits and that means that some cards are 18 bit
only and others 22 bit only.
Not quite.
There is a variant (Rev A) of the KDF-11 (11/23) CPU card that can't
go above 18 bits, but I've never seen one in the field. Every one
I've seen can work in an 18-bit or 22-bit chassis. That's the
limiting factor - what's your backplane? A post-rev-A KDF-11 in a
BA23 has no problems with being configured as a 22-bit system. It's
also possible to run wires to upgrade an 18-bit backplane to 22-bits -
many of us on the list have done that.
I think I will hang on to the RLV12 and RQDXE,
anything else? It would be
great if the memory was compatible.
The RLV12 is a keeper - it works in 18 or 22-bit machines and it
doesn't have the limitation of needing to be stuffed into a
CD-interconnect slot (unlike the two-board RLV11). The RQDXE is handy
if you want to use an RQDX3 in a system other than a single-BA-23
cabinet. If I were keeping memory, I'd keep the larger of your cards
(MSV11-L, -P, -M) and populate the departing 11/23 with the MSV11-D
(as long as you have a serial card for its console, like the DLV11-J,
otherwise, you can configure a small system with the MXV11).
In general, the 11/23 with 32Kwords of RAM and a DLV11J (quad serial)
and RLV11 with a drive or two makes a nice RT-11 system. If you
wanted to run something more elaborate (RSX-11, RSTS/E, 2BSD), I'd
recommend more memory, larger disk, and if possible, a newer processor
(especially with split I&D space like an 11/44 or 11/73), but you
*can* still do a lot with an 11/23 and enough memory and disk. It's
just nicer to have a more advanced processor to go with the extra
space.
I myself don't have an 11/73. My only KDJ-11 systems are a DEC
Professional 380 (a former VAXconsole box) and a loose S-box "11/53"
card that was once a communication device CPU. I wouldn't turn down
an M8190 or M8192, but I haven't run across any for cheap/free, so I
still have a few M8186 (KDF11-A) and M8189 (KDF11-B) boards that do
just fine.
I hope all this information helps rather than obscures your task.
-ethan