Re: Write IIgs disks from Mac ?

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

Jonathyn Bet'nct <jonrelay@napanet.net> wrote:

> "Steven Palm" <n9yty@bigfoot.com> wrote in message
> news:n9yty-2806012210280001@192.168.42.242...
> > I have tried, using a PowerPC 6100 at work under MacOS 9.1, to make disks
> > from the System disks from Apple and other sources I've found.  DiskCopy
> > reports a successful disk creation, but when I try to boot I get a "UNABLE
> > TO LOAD PRODOS" or similar error message.
> >
> > Now, I also tried making the same disk on my Classic at home using
> > DiskCopy 4.2 and System 7.1, and it worked fine.  Strange...
> >
> > I then loaded DiskCopy 4.2 on the PowerPC 6100 at work and tried again
> > from the same image file, and it couldn't make a bootable disk.  I took a
> > drive out of the Apple IIgs enclosure, put it into the 6100, and wrote the
> > disk again.  Still no go.  I put the Mac drive into the IIgs enclosure,
> > and it would boot the one I made on the Classic, but not anything made on
> > the 6100.
> 
> Oh yes, this is all so familiar to me. Don't pay attention to anybody else's
> response to this, I'm the only one who knows what he's doing when it comes
> to this specific problem.

Oh let us all bow to your infinite wisdom.  :-)

> Some people say that PowerMacs won't work. Well, guess what, some of them
> do!

Yes - mine does, but only if I'm really careful.

> There are a few reasons why this isn't working:
> 
> First, somewhere around MacOS 8.5 or so, Apple started tacking on resource
> forks to every single ProDOS file, no matter if you liked it or not. This
> screws up a lot of ProDOS software (ShrinkIt being the most apparent).

This isn't exactly true.  I've done some investigation of this under Mac
OS 8.6, and it appears that the rules are quite simple:

- If the file already has a resource fork, then the copy on a ProDOS
disk will as well.

- As long as the file type and creator information match the standards
established by Apple for ProDOS files (creator 'pdos' and an
appropriately formatted file type), the Finder will _not_ create an
unnecessary resource fork when copying to a ProDOS disk.

In any other case, the file must be written in "extended" format, so
that the Macintosh file type and creator can be preserved.

Applications other than Finder writing directly to a ProDOS disk might
not behave correctly.

It also appears that Disk Copy 6.x doesn't work very well when writing
ProDOS 800K disks (I've never tried it with Mac 800K disks).  Disk Copy
4.2 is a safer bet.

> iMac 233 (Bondi rev A) @ 266MHz
> DiskCopy: fails
> Mac Finder: succeeds

I assume this was using the hack to attach a disk drive to the internal
drive controller?  This is the only method I can think of which would
allow an 800K disk to be accessed by an iMac.  (It isn't an option for
revision C and later models, which removed the controller.)

> However, there is one thing that explains this; it seems that Sony floppy
> drives are better at writing ProDOS disks than other drives are.

I think the distinction is 800K disks rather than specially ProDOS ones.

> Older Mac models used Sony drives, so that's why so many people believe
> PowerMacs won't work (although the above shows differently).

The Powerbook may be a special case - its drive is likely to be a
different mechanism from desktop machines.

The clue as to whether it is a genuine Sony Superdrive mechanism is
whether the drive has the "auto inject" feature, i.e. it grabs the disk
and pulls it in.  Later mechanisms require the disk to be manually
inserted all the way.

> I have a three-step process:
> 
> 1. Copy all the files from the ProDOS disk to a new folder on the desktop.
> 2. Erase the disk in the Mac Finder (be sure to select ProDOS 800K).
> 3. Copy all the files back.
> 
> This may or may not actually work, but it's worth every try.

I'd expect this to work nearly all the time, as it ensures the file
types are correctly set for ProDOS files, avoiding the need to create
extended files when copying back to a ProDOS disk.

The problem with some 3.5" drives and 800K disks may still prevent it
working with specific machines.