IWM(4) | Device Drivers Manual (mac68k) | IWM(4)

# 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.)

# FORMATTING

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.

June 6, 1998 | NetBSD 10.1