Date   : Thu, 19 Mar 2009 10:29:57 +0000
From   : robert@... (Rob)
Subject: Hardware questions

2009/3/19 Richard Gellman <splodge@...>:
>
> The question is, if I implement some control logic somewhere in FCxx, is it
> permissable to use the whole of FDxx as a 256-byte page window, and
> implement my own paging register in FCxx ? Or is there some hard-wiring that
> already implements a paging register in FDFF and FCFF ?


Ooh, that brings back memories - I'd completely forgotten about it
until now, but that's exactly what I did when I built an external RAM
box sometime in the 1980s... although for a Model B.  Never ran into
any issues as to where my paging register was, but I wrote all the
software myself anyway. Is there actually any MOS support at all for
paged RAM up there on the Beeb, or was it just a suggested layout so
as to try and make third-party add-ons compatible?

Rob