10 Jul
2009
10 Jul
'09
3:49 p.m.
The PDP-11/20 that I have from 1970 has H207 core planes in the main
cabinet. The H207 is part of the MM11E subsystem.
Here are the boards in my PDP-11/20 cabinets:
http://www.iamvirtual.ca/collection/systems/minis/PDP11-20/Boards.html
The core plane should be documented in the "MM11-E Core Memory Manual"
(see document DEC-11-HR3A-D). I have a copy of the manual if needed.
--barrym
On 7/10/09, Ethan Dicks <ethan.dicks at gmail.com> wrote:
On 7/10/09, Rick Bensene <rickb at bensene.com>
wrote:
Hello, all,
I recently came into possession of four DEC H207 Core Memory boards.
They consist of a quad-width board that has a large number of signal
steering diodes, with an attached daughter board that has a 4K x 16
"Planar Memory" array made by Electronic Memories. The boards all have
original DEC warranty seals on them, dated June of 1971.
I'm curious as to what DEC machine may have used these boards, and what
support Flip Chip modules (X & Y drive, Sense/Inhibit, and addressing
logic) may have been used with the core stacks to provide a 4Kx16 memory
subsystem.
They sound like the right size and date for an 11/20. I have a few
(since I have the rescued bits of a cut-up 11/20) and can check what
you have against what I have. Can you send me a picture off-list?
I'll compare it with what I have, and I can confirm handle numbers for
the sense/inhibit and XY boards (they should be on a master module
list anyway - they were common in 1971).
Unfortunately for me, I wasn't the only one from that company who got
some parts. I think I didn't manage to retrieve 100% of the core that
was in the three-cabinet 11/20. I am missing at least one core stack
that I know of. I was planning on a modern memory replacement if I
ever get this machine put back together (it was stripped and the PSUs
recycled before it hit the dumpster, and I saved the carcass and as
many boards as I could). My ultimate goal for this is to run first
RT-11 to check it out, then the early version of UNIX that was
recently demonstrated on simh (I still need to come up with an RF-11
emulator; I think I have most of the rest of the hardware that's
required).
Give the 16-bit array size, I assume that it may
have been used in a
PDP-11, but I suppose (with four wasted bits) it could have been used in
some form of PDP-8 system.
Probably not. There are 4Kx12 planes for the PDP-8 (I don't know the
number off the top of my head) and it's not the same as what was used
in the PDP-11. Cores cost too much to "waste" 25% of them.
-ethan