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Date   : Thu, 10 Jun 1999 15:15:34 +0100
From   : jgh@... (Jonathan Graham Harston)
Subject: BBC software to grab DFS disc images

Steven Flintham <steven@...> wrote:
> I'm thinking of (gradually!) copying all of my BBC discs onto my PC's
> hard disc, so that I don't need to worry about them dying of old age and
> so that I can use them conveniently in an emulator. Most of them are DFS
> (only 40T SS as well), so I thought I might as well store them as
> straight disc images - IIRC there's a 'standard' format (.ssd/.dsd
> extension) for this. Assuming I'm not imagining it:
 
> b) Has anyone got a program already written which will run on a BBC and
> create a file on one drive which is the disc image of a disc in another
 
The BACKUP program supplied as part of the HADFS System Disk.  It is
available at http://mdfs.net/Apps/DiskTools/BACKUP
 
On runnings, you are prompted for source and destination drive numbers. 
At these prompts you can also enter filenames, so you could, for example,
copy the disk in drive 0 to a file on an ADFS disk with:
 
Source drive: 0
Dest. drive: -adfs-:1.$.DFSImage
 
It doesn't SetType the output file, you should set it manually to &B22.
 
There is also the program GetDskImg, which runs on the Arch and will make
a 400k image file from a supplied DFS/HADFS/CPM disk.
 
I'm not exactly sure where I've put it, it should be in
/software/DiskReadrs/HADFS but I think it's on another machine.
 
The HADFS Filer application !HADFSFilr allows you to access these disk
images.  The DFS implementation is a bit unimplemented, but HADFS and CPM
work, although with no saveing to CPM disks just yet.
 
!HADFSFilr is available on Arcade in Area 53 - Apps, name 'HADFSFiler',
I'll get round to putting it on the website soon.
 
> While I'm asking, is there any similar 'standard' for ADFS discs? I
 
Soon to be implemented.  See below...
 
"Robert Schmidt" <robert@...> wrote:
> Steven Flintham wrote:
> > a) Is there any documentation on these formats around?
> Here's what David writes:
> Two forms of disc image are presently supported.  The first is single
> sided format.  This consists of a raw disc image of a beeb, 10 sector
> per track, 256 byte per sector disc side.  So the image is ordered
>   track 0,sector 0,
>   track 0,sector 1,
>   .
>   track 0,sector 9,
>   track 1,sector 0
 
So far, so good...
 
> The double sided format uses interleaved tracks:
>  track 0,head 0, sector 0,
>     .
>  track 0,head 0, sector 9,
>  track 0,head 1, sector 0,
>     .
>  track 0,head 1, sector 9,
>  track 1,head 0, sector 0,
>     etc
 
Horrible, horrible, horrible!
 
This means that is a DFS occupies, say, track 1, 2 and 3 on the DFS disk,
then in the image it is not a continues chunck of data that can be
extracted.  You have track 1 then track 1 from the other side to skip,
then track 2, then track 2 from the other side to skip, then track 3.
 
Much preferable is
 
Side 0, Track  0, Sectors 0,1,2,3,4,5,6,7,8,9
Side 0, Track  1, Sectors 0,1,2,3,4,5,6,7,8,9
etc..
Side 0, Track 79, Sectors 0,1,2,3,4,5,6,7,8,9
Side 1, Track  0, Sectors 0,1,2,3,4,5,6,7,8,9
Side 1, Track  1, Sectors 0,1,2,3,4,5,6,7,8,9
etc..
 
Essentially, this is the .ssd format, continuing past track 79 onto the
other side of the disk.  This type of disk image has a defined Archimedes
filetype - &B22.
 
The layout of an ADFS disk image would be exactly the same, ie:
 
Side 0, Track  0, Sectors 0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15
Side 0, Track  1, Sectors 0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15
etc..
Side 0, Track 79, Sectors 0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15
Side 1, Track  0, Sectors 0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15
etc..
 
Richard Harker <rich@...> wrote:
> Does anyone know of a program for the Archimedes which will write one of
> these ADFS images to a disc, or better still let them be used in Risc
> OS, via an image filing system (like PC format hard drive partitions)?
 
!HADFSFilr will soon support ADFS disk images.  I have another little
proglet PutDskImg somewhere which will copy a disk image to a floppy, the
complement to GetDskImg mentioned earlier.
 
All disk handling software will eventually be in the directory
http://mdfs.net/Apps/DiskTools/
 
-- 
J.G.Harston (JGH BBC PD Library) 70 Camm Street, Walkley, SHEFFIELD S6 3TR
jgh@...                - Running on BBCs & Masters with SJ MDFS FileServer
            Z80+6502/CoPro+Tubes/Econet+SJ -- http://mdfs.net/
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