Date   : Fri, 29 Aug 1997 09:09:32 +0100
From   : Chris Johns <cmjohns@...>
Subject: Re: Sideways RAMs

In message <199708271533.IAA13788@...> you wrote:

> Not surprising. I can't remember what signal goes to write enable, but it
> won't be what you expect. You need some extra logic to determine whether
> write enable should be on, and whether the socket your chip is in is the
> correct one to write to. This is why there were sideways RAM boards
> (though I built one myself initially, ISTR the extra logic was only a
> couple of gates

I had/have one (SJ Research which IIRC was also the Acorn User one) which was
just one chip and two wires which you connected to two places on the main
circuit board. These wires were connected to two pins on the SWR chip that
didn't go into the socket (there were two pins missing in the carrier).

I can dig out where the wires go if you like (it means taking my BBC apart
and looking :)) I think I put it in my second machine when I got a Watford
ROM/RAM board a while back.

I also had a little 16k SideWays RAM which only had one wire. After pondering
over circuit diagarams to find out what signal that was I managed to connect
it to an electron with a bit of glue logic (a few gates).
-- 
  ___
 /o o\  Chris Johns - cmjohns@...          
 \ | / http://privatewww.essex.ac.uk/~cmjohnj
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