Date   : Wed, 20 Jul 2005 16:15:42 +0100
From   : jgh@... (Jonathan Graham Harston)
Subject: Re: floppy discs

BeebMaster wrote:
> By the way, it doesn't work in 1770 DFS (I think it is a different format
> control code for the 1770 series).
 
No, the 1770 DFS uses exactly the same OSWORD interface as the 8271 DFS.
That's the whole point of using an API instead of messing with the hardware.
 
The only difference is that the 1770 controller can't build up an empty
track on the fly, and has to be fed the whole track data. DFS builds an
empty track in memory just above OSHWM - which is where PAGE usually is, so
trashing the program that's trying to format! I have added *FX180,64 to my
format program to temporarily move OSHWM to &4000, so the 1770 DFS builds
the track data away from the program.
 
-- 
J.G.Harston - jgh@...                - mdfs.net/User/JGH
Taxation is like diary farming. You have to extract the maximum amount of
milk with the minimum amount of moo.