Date   : Fri, 31 Jan 1997 20:54:08 +0000
From   : Mike Tomlinson <mike@...>
Subject: Re: Disk image formats?

In message <32F1B5D0.6A99@...>, Robert Schmidt <rsc@vingmed.no>
writes
>
>Lucky you to have a PC on which BBC disks can be read!  *envy*

I read the help files included with FDC, and found an old IDE/floppy
controller which uses separate 16Mhz and 9.6Mhz crystals, rather then
the single 24Mhz unit used by most.  So far I have had little trouble
reading 40T discs in a 360K drive, but have not been able to read 80T
discs in a 1.2M drive.  My next move is to connect my old Beeb's 40/80T
switchable drive to my spare PC and try that.

>Wouter Scholten's format was proposed as a sort of a common denominator 
>for BBC files.  It is very flexible, files can be interpreted on any 
>system, each BBC file is available individually, the information about 
>each file is available in a readable and text-editable format, and 
>very importantly, BBC file names are not limited by the host system's 
>limitations.  It is very easy to convert such collections of files to 
>any other format.  I adopted this format as the standard for my BBC 
>software archive, and have been very happy with it.

The problems I have with that are:

1) because of the limitations of FAT on the PC, it becomes very
expensive in terms of disk space to store lots of small files. The
impact is doubled when one needs to write a separate .inf file for each
BBC file;

2) many of the disks I have are compilations of several games on one
disk with a menu-based loader, and it would be murder to try and
separate out the individual files.

>Also, I've made the decision to provide each software title in it's own 
>ZIP file, instead of storing full disks in this archive format - also 
>for convenience.

Fine - *if* you have each individual application/game in its original
format, or on disk without other apps being added in.

Unfortunately, I don't - which is really why I asked if anyone would be
interested in disk images, rather then collections of files.

>Disk images, in comparison, are inherently hard to work with - even on a 
>BBC or in an emulator.

I appreciate that; however, that is all I have. Conversion utilities do
exist, however.

>> I was thinking of using FDC or Anadisk to read the discs and then
>> converting them to DFFS format, then zipping them using -eX (extra
>> compression) before putting them up.
>
>DFFS can't be converted to anything else (yet).

OK, how about if I just zip each disc image without converting it to
DFFS?  Then the image could be unzipped and converted with whichever
emulator before use.


-- 
Mike Tomlinson
Alexander Graham Bell's worst nightmare: "This is Watson, I'm
sorry I can't come right now, please leave a message."