PDP-8 /e/f/m memory

[Allison]

>
>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...
>> 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 

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.

>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