Re: P00-format + new D-format

From: Ruud Baltissen (
Date: 1998-10-12 20:58:24

> I myself can produce disk dumps from 8050 disks (~500k) and
> 8250 disks (~1M) per disk with my setup. They have up to 29 sectors and
> up to 77*2 tracks. 
> They also handle up to 224 directory entries.

See my D16-format as an extended 8250-disk with 156 sectors and 255 tracks.

> What actually are you planning to do? I mean, either provide standard
> CBM formats, or simply use the filesystem directly.

????: for me 'stanard CBM formats = use the filesystem directly'. Anyway, even 
with this 16MB-floppy it should be possible to use the direct floppy-commands 
like blockread etc., just like with D64-file. Commands which are not possible 
with P00 or plain DOS/UNIX-files.

> I think 1M per disk image seems fine already, and for larger files,
> simply use the host systems directory structure.

I intend to support DOS, P00, T64 and all known Dxx-formats. You could do me a 
favour by giving me the following info of all known formats if it is not to 
much trouble:
- tracks
- sectors / track
- track(s) used for directory

> BTW, VICE handles directories in the host directory tree as "DIR" files 
> (in the directory) and you can 'open 1,8,15,"cd:foo/bar"' into them :-)

Two minds, one thought :-) In my case I also support the command NOT 
using the colon.

> Just FYI: There is a new .G64 disk image file format on the way. It is
> basically defined and finished, only the docs have to be written up.
> It is a (AFAIK) a vc1541 disk image in GCR format. It will be supported
> by several emulators and can handle more than the usual 35 tracks.

What is the advantage of this format above D64? The only thing I can 
think of is emulating disks with errors made on purpose to get a kind of 
copy protection.

BTW, what does your 8296 show at startup?

Hallo Levente,
> What about a flexible disk image format, with variable parameters?
> I mean, if it contained a header, from which the programs could decide
> if the image contains X or Y tracks/sectors etc.

On itself not a bad idea at all, in this way you could define a disk which 
could fit on a 1.44 MB floppy. But to be honest, this would be the only 
advantage of such a disk format. The others, D64, D81 etc. have the 
advantage that you can copy them 1-to-1 directly to an existing C= floppy. 
My D16-format has the advantage of being big but that is the only 

Hallo Stephen,

> Yup.  That's why CMD hard drive partitions are limited to 16 Megs.

So somebody already used my idea, nice to know :-)

About (sub)directories, if the root is the entry, the $ command starts 
with sector 1, track 18. If it isn't, the emulator looks up the DIR-file 
going with the CD-command and uses its sectors as starting point. If there 
is a chain (cd /xx/yy/zz) then it has to follow it completely. Of course I 
don't intend to do it every time, I save the track/sector of the last 
directory-entry and only update it when needed.

Groetjes, Ruud

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