Date   : Thu, 31 May 2001 05:11:14 +0000
From   : "W.H.Scholten" <wouter.scholten@...>
Subject: Opus Challenger disasseemly/*OPT 0 on any DFS

Graham Bisset wrote:

> [ tom seddon ]
> >One bug is that formatting a 40 track disk results in an 80 track disk, just
> >with only the first 40 tracks formatted. needless to say this does not
> work in
> >a real 40 track drive! To fix this you must do a *OPT8,1 before
> formatting. On
> >my drive at least you can hear the difference.
> 
> Actually thats documented in the manual, so its more of a "feature".

Yep, but it's messy and there's no point in formatting the first 40
tracks on a 80 track disc, so I'll try to change format to switch to 40
track mode. Also, this does lead to a real bug: after *opt8,1 and then
read/write from 80 track floppy, the drive will go beyond track 80 (it
will try to go until 160). You have to press break quickly to prevent
the drive from getting damaged (awful sound when it goes beyond 80...).
Happened a few times when I needed to make 40 track discs to read on my
360K pc drive in 1995/1996.

> The
> command *4080 <setting> "sets the filing system so that 40-track discs may
> be used with an 80 track drive".

The 1.01 version does not have *4080. *opt8 replaces it as noted in
the addendum to the manual. If it works for you, you have an older
challenger rom.

Btw, I mentioned *OPT1,0 as a bug. This was of course not the case. It's
*OPT 0 that gives a bad option, and DNFS/Watford 1.43 are some DFS'es
that allow this (possibly as a NOP or as *OPT 1,1 to give approx the
same meaning as on cassette?).

I've located the mode 7 code and wrote some new code for it. Will check
some more data areas for addresses, change some more things and compile
the first new version in a few days...

Regards,

Wouter