Re: 800K drive on an iMac?

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

Dennis Jenkins <dennis@usb.com> wrote:

> Where can I find a detailed description of this encoding scheme
> (online)?

I have no idea whether there is an online reference.

There is a trick: the 5.25" and 3.5" drives use different sector
structures.  The underlying "nibble" encoding may the same (4-and-4 for
the header and 6-and-2 for the data), but there are several differences
in the sector header, and there is more data per sector on a 3.5" disk,
which will require changes in the way the 6-and-2 data is organised.

The 5.25" encoding has been analysed and published widely in book form.
I've only seen the details for the 3.5" sector format in the IIgs
Firmware Reference (summary only), and possibly in the Copy II+ manual.