Date   : Tue, 07 Apr 2009 00:52:00 +0100
From   : afra@... (Phill Harvey-Smith)
Subject: Writing BBC Disc Images on Linux

me@... wrote:
> On 6 Apr 2009, at 21:29, Michael Firth wrote:
> 
>> Surely that will only work if the target floppy is already
>> formatted to match the image you want to write to the disk?
> 
> No, it's doing a raw write to the floppy device. In fact it will 
> destroy any formatting already on the disc and replace it with
> however the disk image is formatted.

That's simply NOT true, yes it will overwrite the sectors on the disk
with the data from the image, but it will NOT format the disk or change
the layout of sectors on the disks.

In fact without additional configuration you will not be able to read
BBC disks due to them being single density (Acorn DFS), and 256
bytes/sector (DFS and ADFS).

The fdutils package can be used to configure the drive correctly,
including doing things like double stepping if using a 40 track disk in
an 80 track drive, the one thing you have to remember to do is use
fdutils to set the parameters every time you change disks.

I can't remember off hand if I have used linux to read DFS disks, but I
have successfully read/written Dragon 32/64 disks under linux using
fdutils and dd. (Dragon disks are 40 or 80 track single or double sided,
and 18 x 256byte sectors per track).

> This only works for disk images that lack any kind of header and are
>  basically just a binary dump of the disc - I don't know whether .ssd
>  qualifies. .dsd certainly does not.

This part is true.

Dammit, I meant to send this to the list the brain-dead list reply 
policy strikes again ! David apologies if I seemed like I was getting 
stroppy, that's not what I intended :)

Cheers.

Phill.

-- 
Phill Harvey-Smith, Programmer, Hardware hacker, and general eccentric !

"You can twist perceptions, but reality won't budge" -- Rush.