Re: ProDos Disk Images

["Bryan Villados" <news002@macgeek.org>]

Maybe I'm wrong at the following assumption...

Is there a byte-level difference between a ProDOS diskette created on a
manual-eject drive versues an auto-inject drive? I would think that could be
the only cause, on a byte/data level. And, with Paul's testing alone, this
strengthens my assumption. I wish there was some sort of utility that could
be used to compare diskettes on a track/sector level, comparing a disk made
with one type of drive, and another made with the other type.

I'm reading the A2 FAQ, part 6, question #27. Looks to me that for a
diskette to be bootable, all it needs are certain files to reside on the
diskette. If I remember my DOS 3.3 correctly, the first few tracks contain
the bootstrap loader, so the disk could be file-less, but still be bootable.
Interpreting the FAQ, ProDOS is like the Macintosh OS where the boot files
could be anywhere on the diskette, and still be bootable. I'm wondering now
if maybe the placement of the files on the diskette, or the ordering of the
files themselves in the ProDOS' version of the VTOC (I don't know ka-ka
about ProDOS inners) could be a factor? A track/sector comparison would show
these differences. Going along with Paul's theory about the chipset being
the factor, the outcome of that comparison would be interesting.

Seeing Paul mentioned the chipset, maybe the chipset does some weird
ordering of the bytes, or maybe even the operating system itself does this.
Paul, which version of Mac OS are you running on the 4400? And, what are the
steps you're using to make the bootable diskette? I have a Power Mac 8600
myself, but the earliest OS I can run on it is 7.6.1. As a controlled
experiment, I'm wondering if someone were to try creating a bootable ProDOS
diskette on a Macintosh running the same OS as your 4400, and native to the
auto-inject drive. That could help further pin-point whether it's a disk
chipset, OS version, disk drive, or maybe even a PowerPC vs 680x0 related
issue.

--- Bryan


"Paul Grammens" <grammens@svn.net> wrote in message
3e2c6caf@news.svn.net">news:3e2c6caf@news.svn.net...
> I recently picked up a Mac 4400 with a PC Compatibility card;  it has a
> 133mhz Wintel PC on a card in addition to a 200 Mhz Power Mac.  I did some
> experiments to see if I could create bootable ProDos disks. I knew the
> manual inject floppy was not capable of making a bootable ProDos disk, but
I
> tried anyway. It creates the disk, and can read the disk, but the disk
> wouldn't work in my IIc +.
>
> Next I connected an auto inject floppy from an SE/30. As soon as power was
> applied, the eject motor came on and stayed on. I found the pinouts for
the
> floppy on the two types Mac, and discovered that pin 9 has +5V on the
newer
> manual eject drives, but is not connected on the auto inject drives.  Pin
20
> has +5V on the older drives, but is not connected on the newer ones. I
> experimented with that, and found it is not necessary to supply 5V to it
> because pin 11 supplies 5V.
>
> I cut the trace on the floppy drive PC board to isolate that pin, and then
> found that the drive worked normally in the 4400.  It reads, writes, and
> formats properly.  So if you want to use an auto inject floppy in a Power
> Mac, disconnect pin 9. The pins are labeled nicely, and I didn't want to
do
> any cutting on the 4400's cable, so this was the best solution for me.
>
> However, I still couldn't make bootable ProDos floppies with the 4400.  I
> reconnected the floppy to the SE/30 and verified that it could still make
> bootable floppies there. I also used the same disk image on the SE/30 and
> 4400, just to eliminate that variable.
>
> So the bottom line is that it seems that the floppy controller chip in
this
> Power Mac does not allow even a good ol' auto inject SuperDrive floppy to
> make usable ProDos disks.
> -Paul
>
>