14 Aug
2006
14 Aug
'06
1:50 p.m.
Subject: Re: PDP-8 /e/f/m memory
From: "Jay West" <jwest at classiccmp.org>
Date: Mon, 14 Aug 2006 12:41:55 -0500
To: "General Discussion: On-Topic and Off-Topic Posts" <cctalk at
classiccmp.org>
Chuck wrote...
Must have been two 61256. the 2114 is a 1kx4 memory and three would be
needed to create a word wide memory. I know this as I made a 3k ram for a
6100 system.
The 61256 is 32kx8, two would be 32kx16, throw away 4 bits and you have
a 32k word memory cheap.
I did a semiconductor memory design for the
OMNIBUS several years ago. It
was for an -8/e and 32kW using two SRAMs. I never got to documenting it
outside of my notebook, but if there is enough interest, I could do some
schematics. It is battery backed, so its pretty much equivalent to the
core I was replacing.
Maybe it was your diagram I got years ago. Someone did a nice 32kw board for
the 8e using two 2114's I think it was. I have the schematics somewhere still. The only reason I didn't build it right away
was because at the time
I got them, the person said "these schematics aren't quite final, there may
have been some tweaking afterwards that didn't make it to the schematic" so
I just sat on them.
A known working design - I'd want to build that in a heartbeat :)
Jay West
I figured before I embark as it will be winter before I WWrap it
(too warm now) I'd check and see if someone else attacked the problem.
Allison