Date   : Wed, 22 Jun 2005 19:52:20 +0100
From   : Mike Tomlinson <mike@...>
Subject: Re: Watford Electronics DFS

In article <42B987B2.7070904@...>, Andrew Benham
<adsb@...> writes

> maybe there were two versions of
>the Watford 1770 disk upgrade, and only the later ones were
>compatible.

That's correct.  In early Watford 1770 disk upgrades, the 1770 chip was
mapped at a different physical address.

The Watford DDFS 1.54T ROM works fine with the Acorn 1770 upgrade, as by
this time Watford had redesigned their interface so that the 1770
occupied the same addresses as the Acorn one.