On Fri, Jan 6, 2012 at 6:35 PM, Pete Turnbull <pete at dunnington.plus.com> wrote:
Ethan Dicks wrote:
Just KDF11-A vs KDF11-B... KDF11-A may or may not
be 22-bit (only Rev
A is 18-bit). ?All -B are 22-bit. ?Dual-height CPU only vs Quad-height
CPU plus dual SLU plus on-board Boot ROMs.
Yes, plus LTC, of course.
Yes. That too.
A minimal /23+
system could be as little as 2 modules - KDF11-B plus
memory - use the second SLU for a TU58 or TU58 emulator and you could
boot RT-11. ?A /23 system will have more boards.
You can actually do that with a KDF11-A and an MXV11-B as well.
Ah, yes. Good point. I rarely remember the MXV11-B, mostly I think
because I mostly worked with systems that had one or more boards of
"real" memory and either a DLV11J (in BA-11s) or some type of
quad-height quad serial card (in BA-23s). My own first PDP-11/23 was
a customer-returned "HASPBOX" from the pre-COMBOARD days of Software
Results Corp. It was shipped with 100% DEC hardware and 100% SRC
software to be a bisync serial I/O front-end processor for a larger
RSTS machine, probably a PDP-11/70. When the customer decommissioned
their RSTS box, they didn't know what to do with the little BA11N
hanging off of it, so they read the sticker and sent it back to us. I
bought it for peanuts... in 1985, $300 got me a KDF11-A, four 32K
memory cards (MSV11-D?), an LPV11, a DLV11J, some flavor of DEC sync
serial board with a COM5025 USART, and a BDV11. I think I had to buy
my own RXV21, and I know I had to buy my own RLV11 ($100 at the time
since the RLV12 was just out and didn't need a CD-interconnect
backplane, so was very popular). I borrowed a VT100, an RL01, and an
LA180 from my PDP-8/a and ran RT-11 V5.0 on it. I made my living for
a couple of years on that box. At one point, I even ran the extra
backplane wires to manually upgrade it to 22-bit, then upgraded the
dual-height memory card that was half-full of 4164 DRAMs, from 128K to
256K IIRC. Lots of soldering. Took three passes to find all the dry
joints, but I did get it working with no strange crashes (just crashes
caused by my buggy MACRO-11 code. ;-)
Fun times. I'm still happy I found someone to pay me to build and
program PDP-11s. Great job. No budget for MSCP disks, though. My
experience with that came (two years?) later once low-end MicroPDPs
were starting to go for cheap.
-ethan