Date   : Thu, 31 May 2001 22:55:57 +0100
From   : Graham Bisset <bbc@...>
Subject: Re: Opus Challenger disasseemly/*OPT 0 on any DFS

At 05:11 AM 5/31/01 +0000, you wrote:
>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). 

Mmm....strange, never experienced that on my machine, but then again
although I was using a 40 track drive as well, I probably always reset the
machine in between times.

>> 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.

I have 1.01, however I still have the complete manual, but I suspect the
one page addendum has gone missing, hence the reason I forgot about the
change.

I *do* recall though, that there was a 1.02 floating about when I was
running the Challenger system, but with no facilities for writing an eprom
back then, I never did get to try it nor did I bother trying to get a copy
of it.

>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...

Great, keep us up to date with progress, be nice to breath new life into
the system.  Actually now I have the ability to upgrade it to a 512K system
:-)

Cheers
Graham