June 6, 1998 IWM 4 mac68k

### 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 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.