Date   : Sun, 22 Jan 2006 20:31:52 +0000
From   : Andrew Benham <adsb@...>
Subject: Re: eBay What is this?

Jonathan Graham Harston wrote:

> Unfortunately, the ADFS OSWORD &72 sector commands refuse to work
> if a drive has not been mounted.

Err, are you sure about that ?  If so, then it would be impossible
to ever format one's first disk under ADFS.
Maybe you need to do an "F BREAK", to start ADFS with no drives
mounted ?

> Doublely stupid, ADFS refuses to
> MOUNT a drive if it does not have an ADFS filesystem on it.

No, that's sensible.  MOUNTing a disk tells the user (and the
file system calls) that the disk has a valid file system on
it and is ready to be used.

> The only way to do it is to feed SCSI commands directly to the
> hardware, which, at the moment, is a bit beyond me.

Osword &72 is essentially Acorn's wrapper around the SCSI command
block.

Maybe my memory is playing me up, but I'm sure that you can use
Osword &72 on an unmounted disk.  I remember recovering files
by hand from Unix floppies on the BBC.  And surely the ADI ROM
must use Osword &72, and that'll read just about anything (I
always think of Osword &7f as the universal single density
call, and Osword &72 as the universal double density call.

-- 
Andrew Benham         adsb@...       
Southgate, London N14, United Kingdom

The gates in my computer are AND OR and NOT, not "Bill"