PDP-8 /e/f/m memory

Patrick Finnegan pat at computer-refuge.org
Tue Aug 15 00:17:58 CDT 2006


On Tuesday 15 August 2006 00:38, Ethan Dicks wrote:
> On 8/15/06, Patrick Finnegan <pat at computer-refuge.org> wrote:
> > > On Aug 14, 2006, at 8:54 PM, Ethan Dicks wrote:
> > > >> > Why not use a pair of 62256s?  32Kx16 and ignore 4 bits.  It'd
> > > >> > even be easy to use a Dallas DS1210 or something like it to
> > > >> > provide battery backup.
> > > >
> > > > 32Kx8 are easy to find as old cache RAM.  They are not, however, low
> > > > power, and would not be the best solution if you wanted to hang a
> > > > battery off of them.
> >
> > I thought the point was to use them in a real PDP-8 e/f/m, in which case
> > the extra power would probably be a non-issue..
>
> The extra power has to do with battery life, not power-on consumption.
>  The amount of power that two cache SRAMs and some buffer chips takes
> up is utterly invisible compared to eight set of 4K core stacks (but
> you need two OMNIBUS chassis to hold that many cards; a more typical
> installation is four 8K stacks or a couple of third-party 16K stacks).

Yeah, I realized that after re-reading your message. :)

Still, if you're just looking for memory, and don't care about battery backup 
(like MOS memory replacement), I think that cache SRAM is a reasonable 
choice.

Pat
-- 
Purdue University ITAP/RCAC       --- http://www.rcac.purdue.edu/
The Computer Refuge               --- http://computer-refuge.org



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