On Wed, 1 Jul 2026, Matt Jacobson wrote:
The Mac Quadra 800 contains a "SuperDrive" floppy drive that supports
both GCR (400 kB and 800 kB) and MFM (720 kB and 1440 kB) diskettes.
Implement an emulated version, to be controlled by a forthcoming SWIM2
device.
For GCR, the emulated drive encodes the BlockBackend's data in the Apple
GCR format and exposes it to the controller via sony_drive_read_byte().
The bytes are decoded not by the controller but rather in software by
the Macintosh ".Sony" driver. The drive also adds the sync bytes and
addressing marks that software expects.
For MFM, much less encoding is needed. The sector data passes through
from the BlockBackend unmodified, and the drive only adds sync bytes and
addresssing marks.
Maybe these last two paragraphs explaining theory of operation could go in
a comment but which is easier to see than looking up a commit message but
I'm OK with it either way.
Signed-off-by: Matt Jacobson <[email protected]>
I can't tell if all of it is correct but looks reasonable to me so
Reviewed-by: BALATON Zoltan <[email protected]>
