NAME
iwm,
fd —
floppy disk
driver for IWM and non-DMA SWIM controllers
SYNOPSIS
iwm0 at obio?
fd* at iwm0 drive ?
DESCRIPTION
The
iwm driver interfaces to the built-in and external floppy
disk drives on the Macintosh. It supports double-density media, written in
Apple's proprietary GCR format. Currently, there is no disklabel support for
the floppy drives. Instead, the
iwm driver sets up a fake
in-core disklabel, using the minor device number to select from the supported
disk formats.
The following formats are supported:
Partition |
Size |
sides |
tracks |
sectors/track |
a |
800Kb |
2 |
80 |
10 (default) |
b |
400Kb |
1 |
80 |
10 |
c |
800Kb |
2 |
80 |
10 |
(The above table describes the logical mapping as implemented by the driver; the
physical layout of GCR floppies has 8..12 sectors per track.)
The
iwm driver does currently not support floppy disk
formatting.
SEE ALSO
Apple Computer, Inc.: "Inside Macintosh", Vol III-33f.
(Addison-Wesley)
Apple Computer, Inc.: "New Technical Notes DV 17 - Sony Driver"
Neil Parker: "iwmstuff"
eject(1)
HISTORY
The
iwm interface first appeared in
NetBSD
1.4.
AUTHORS
Hauke Fath put together the beginnings of the
iwm driver in
1996 from the sparse documentation in "Inside Macintosh", Neil
Parker's "iwmstuff" documentation for the Apple IIgs and a long,
hard look at the .Sony driver.
BUGS
The FFS code is incapable of dealing with a varying number of sectors per track.
We have to fake a mapping and so lose FFS support for hardware parameters like
transition times.
The driver only supports an obsolete format.