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fd(7A)

Amiga floppy disk driver

From the original Amiga UNIX 2.1 manual. Some things it mentions may not be in this release.

Also by this name: fd(4), File formats and configuration files

fd - Amiga floppy disk driver

/dev/dsk/fd* and /dev/rdsk/fd* are special files which access the Amiga floppy disk drives. Two formats are currently available with a standard Amiga floppy drive: "Amiga format" and "IBM format". The only supported density is "double density", that of the Amiga 880K 3.5" format and the IBM-PC 720K 3.5" format.

The device names are of the form:

/dev/dsk/fdnfd block device (for mounting)
/dev/rdsk/fdnfd raw device (for direct I/O)
/dev/rdsk/fdnfdf format device (for formatting)
where 
n is the drive number (0-3).
f is the format (a for Amiga, i for IBM).
d is the density (d for "double density").

A floppy disk is formatted by writing data (such as zeroes) to its format device.

Since double density Amiga format is the most common on Amiga computers, the "ad" may be ommited from the fdnad[f] names; i.e., /dev/dsk/fd0 is shorthand for /dev/dsk/fd0ad.

/dev/cage is a special file which, when opened, causes the opening process to become the floppy demon.

/dev/dsk/fd*, /dev/rdsk/fd* - special files
/dev/cage - enslaver

format(1A), mount(1), tar(1).