Date   : Thu, 03 Jun 1999 12:55:34 +0200
From   : "Robert Schmidt" <robert@...>
Subject: Re: BBC software to grab DFS disc images

Steven Flintham 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:
> 
> a) Is there any documentation on these formats around?

David A. Gilbert introduced the format (i.e. the sector-by-sector
layout) with his BeebEm, so the docs for his emulator gives the best
description there is.  Both formats are only straight dumps of the data,
fairly intuitive - ordering only becomes an issue with .dsd files.  I
think it was my humble self who introduced the extensions - just to make
it easier to distinguish single/double-sidedness.  Size (40/80) can be
easily determined by the image file size.  The formats do not handle
weird sector sizes.
 
I have not come across such a program yet.

I've come across some ADFS images - I think Chris Richardson offers some
ADFS dumps in his excellent 8BS archive.  I've never really used them,
so I don't know their peculiarities.  Chris has chosen the extension
".A" for such images.

Here's what David writes:

Disc image formats

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

  etc.

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

This double sided format can be produced using the !Zap editor on the
Acorn
Archimedes with a 5 1/4" drive.  The author intends to write a utility
for
Linux to do the same thing.

--
Robert Schmidt <robert@...           > Software Engineer
Technoguide AS: http://www.technoguide.no
Tel: +47 22510463  Fax: +47 22734749
Private: http://www.nvg.unit.no/~rsc
Tel: +47 22606076 

    jeg lukker et oye og ser halvt
    jeg  lukker begge  og ser  alt            -- seigmen