Re: (bootable) ProDOS floppies from Power Mac

["Lee Cremeans" <lee@lcremeans.homeip.net>]

"Michael J. Mahon" <mjmahon@aol.com> wrote in message
20030216182814.29567.00001292@mb-mv.aol.com">news:20030216182814.29567.00001292@mb-mv.aol.com...
> Lee Cremeans wrote:
>
> >"Simon Williams" <*email*@*luddite.ca*> wrote in message
> >2161326.UNBLMUSA@news.telusplanet.net">news:2161326.UNBLMUSA@news.telusplanet.net...
> >>
> >>
> >> On Sun, 16 Feb 2003 10:45:07 -0800 "Paul Grammens" <grammens@svn.net>
> >wrote:
> >>
> >> >
> >> >
> >> > "Simon Williams" <*email*@*luddite.ca*> wrote in message
> >> > 216435.ORKFGANX@news.telusplanet.net">news:216435.ORKFGANX@news.telusplanet.net...
> >> > > Hello nay-sayers.
> >> > >
> >> > > I recall some time past, there was a thread discussing the
> >impossibility
> >> > > of creating bootable ProDOS disks from a Mac with a 'force-feed'
> >floppy
> >> > > drive. Seems it ain't necessarily so. Anyway, for what it's worth,
> >> > > here's what I've managed to pull-off:
> >> > >
> >> >
> >> > Are you able to boot a IIgs with the disk you create?  You don't
> >> > specifically mention that.
> >>
> >> Yes. I've made both GS/OS 5 & 6 and ProDOS startup disks this way... :)
> >
> >I've been able to do it too, back when I had a working floppy drive. I
think
> >part of the problem is using 1.44 MB (2MB unformatted) media; it works
fine
> >in an old Sony auto-inject drive, but the newer Power Mac floppies do
> >something funny with the write current (I'm guessing) and write a fainter
> >image.
> >
> >I've usually been able to get around this by writing each disk in a
ProDOS
> >set twice; the resulting disk works great on either one of my machines.
>
> You should know that "writing a disk twice" does _nothing_ to increase
> the level of the recording.  In fact each successive recording is
relatively
> uncorrelated with the previous recording(s) at the bit level, because of
> normal tiny speed variations during reading and writing.
>
> This is the reason that several bytes worth of "extra space" are allocated
> in the "data" portion of a sector (the part that is re-written), so that
random
> timing variations don't cause the data sector to overwrite the following
> sector's address marks.

The weird thing is, it did seem to work for me. (Of course, I was also using
not-very-good disks at the time; they didn't even work well formatted as
1.44MB.)  Either way, I have been able to get a II-readable disk out of my
7600 before...I'll post again if anything's different on the new drive.

-lee