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
NetBSD1.4.
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.