Date   : Thu, 26 Jan 2006 00:46:01 +0000
From   : jgh@... (Jonathan Graham Harston)
Subject: Re: eBay What is this?

Andrew Benham <adsb@...> wrote:
> 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
 
Yes, I am definately sure, from the HASSLE!!!! ADFS gave me when
writing the IDE drivers. And from years back when I tried reading
and writing sectors on disk formatted with 16*256 sectors per
track, but without an ADFS filesystem stored in them.
 
> to ever format one's first disk under ADFS.
 
The *AForm command tickles the hardware directly.
 
> > 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.
 
No, to me it tells ADFS to use that drive for all future access
where no drive is specified. Another annoying thing is that *MOUNT
*actually* *accesses* *the* *disk* before any file function is
called. Which means you *must* have a disk in the drive.  Grumble
grumble.  I ensured that HADFS explicitly *does not* do this.
There is absolutley no disk access until a disk access is
absolutely, essentially needed.
 
> 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
 
You get 'No directory' error.
 
> by hand from Unix floppies on the BBC.  And surely the ADI ROM
 
The way I've done it in the past is to mount an ADFS disk, then
swap it for the disk I want to actually read from.
 
> must use Osword &72, and that'll read just about anything (I
 
ADI tickles the hardware.
 
> always think of Osword &7f as the universal single density
 
True.
 
> call, and Osword &72 as the universal double density call.
 
True, but only for disks with 8-bit ADFS boot sectors on them
(free space map and root directory).
 
-- 
J.G.Harston - jgh@...                - mdfs.net/User/JGH
BBC BASIC for Windows and Internationalisation
  See http://mdfs.net/Software/BBCBasic/Windows/ProgTips