Re: ProDOS amd Mac system 8.n and above

[dempson@actrix.gen.nz (David Empson)]

Bart <you@somehost.somedomain> wrote:

> If you wish to mount a ProDOS disk on a Mac running a OS above System 7.n  you
> must 1st turn off file sharing.  That is, a filesharing Mac cannot mount a
> ProDOS disk.  This is described in all sorts of technical write ups but I have
>  a very simple question that has never been addressed concerning thius:
> 
> Why?
> 
> Is there a technical reason that filesharing and ProDOS are incompatable?

The original implementation of ProDOS (as used by ProDOS-8) wouldn't be
compatible with AppleShare, because the server needs to write
Mac-specific information onto each writeable volume, including filenames
which exceed the ProDOS limitations.

The extended storage type introduced with GS/OS allows Mac-specific
information and resource forks to be retained on each file.  I don't
recall offhand whether it can also store full Mac filenames (31 8-bit
characters, allowing anything except a colon), but I think not.

If the file system doesn't support full Mac filenames, then it cannot
support the AppleShare virtual file system, which expects to be able to
store the full range of Mac filenames.

It would have been possible to treat the ProDOS volume as read-only for
file sharing.

> on a related note: Anyone know of a way to mount ProDOS volumes under OS X?

Yeah, right.  :-)

Someone would have to write the appropriate foreign file system support
code (as a kernel extension or whatever), provide a 'mount_prodos'
utility, and modify whatever else is needed to recognise the volume.

I'm only just starting to learn Mac OS X programming, so it may be some
time before I'd be in a position to even consider such a project.

-- 
David Empson
dempson@actrix.gen.nz