Date   : Wed, 22 Jun 2005 22:49:36 +0100
From   : Mike Tomlinson <mike@...>
Subject: Re: Watford Electronics DFS

In article <4d7f30739cinfo@...>, Sprow <info@...> writes

>Now I'm confused.

That's my line :)

> I'm sure I had a Solidisk DDFS at some point where the "D"
>was for dual.

We're talking about the Watford interface here though :)

>The interface board then had both an 8271 and a 1770, and a toggle switch at
>the back of the case to select one or the other. This way games which
>expected an 8271 could see an 8271 and the 1770 could operate the rest of
>the time.

You're thinking of the Solidisk DFDC (Dual Floppy Disc Controller.)
Again, it came in two variants; the later one mapped the 1770 at the
"official" Acorn memory addresses and was compatible with the Acorn 1770
ROM.  The early one was incompatible and only worked with its own ROM.

Mike