Date   : Sun, 16 Sep 2007 22:53:43 +0100
From   : robert@... (Rob)
Subject: Working out disk sizes...

On 16/09/2007, Jules Richardson <julesrichardsonuk@...> wrote:
>
> I still haven't figured out what happens to the drive numbering with 'weird'
> combinations of filesystems (ADFS small / medium filesystems on upper / lower
> surfaces of the same disk, and / or DFS in the mix etc.). Or does the drive
> surface numbering always stay the same - and it's just that 1 and 3 might be
> invalid in certain situations? Not sure where that's documented...
>

AFAIK DFS always uses 0&2 for the two heads on the first drive, and
1&3 for the two on the second drive.  You can take a brand new
unfomated floppy and format 'drive 2' and only ever use the second
surface.

ADFS always uses 4 for the first drive, and 5 for the second drive,
just using  the first head, and only using the second head if you want
the larger format.  Hard drives are numbered from 0.

If you don't have a hard disc, you can use 0 and 1 for each floppy
drive too, but TBH I'd not recommend it, purely for compatability and
confusion reasons..

I don't think you can start an ADFS filesystem on the second side of a
disc, and thus have two serperate ADFS filesystems on one physical
floppy. You can start a DFS filesystem on the second side, though, so,
you can have -DFS-:2.$.file and -ADFS-:4.$.file on either side of the
same physical floppy and have them both accessable.

Obviously taking the floppy out and putting it in the second drive
increments by 1 all drive numbers in the examples above..

Rob