Subject: Re: Need IWM information...
To: None <>
From: Tom 'moof' Spindler <>
List: macbsd-general
Date: 02/17/1994 21:27:31
> I'm looking for detailed information concerning the 
> IWM (Integrated Woz Machine) in effort to build a
> floppy driver for MacBSD.
> In particular, I'm looking for information on how to
> detect the beginning of a sector, GCR (Group Code
> Recording) format, and Macintosh floppy disk formatting.
> I'm looking for the Book, "Beneath Apple DOS" which
> presumably has information about GCR and the 3.5''
> floppy drive, but can't seem to find it anywhere...

Beneath Apple ProDOS has the stuff on the old Apple II 5.25 disk
interface and format. I know that the format was _similar_ for the II
3.5 inch drive, and slightly different again for the macintosh (tags and
checksums, fer instance), and as for the FDHD, I have no idea.

I know the 800k stuff uses d5 aa 96 as the track prolog, d5 aa ad as the
sector prolog, and uses 6 & 2 encoding (each "byte" on the disk only
holds six bits, and the extra two bits for all the bytes in the sector
are glommed together at the end).

Never thought that being an Apple II pirate would one day be useful for
the mac. :)