Re: (bootable) ProDOS floppies from Power Mac

[mjmahon@aol.com (Michael J. Mahon)]

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.

-michael

Check out amazing quality 8-bit Apple sound on my
Home page:  http://members.aol.com/MJMahon/