*fdformat* does a low-level format on a floppy disk. _device_ is usually one of the following (for floppy devices the major = 2, and the minor is shown for informational purposes only):
....
/dev/fd0d360 (minor = 4)
/dev/fd0h1200 (minor = 8)
/dev/fd0D360 (minor = 12)
/dev/fd0H360 (minor = 12)
/dev/fd0D720 (minor = 16)
/dev/fd0H720 (minor = 16)
/dev/fd0h360 (minor = 20)
/dev/fd0h720 (minor = 24)
/dev/fd0H1440 (minor = 28)
....
....
/dev/fd1d360 (minor = 5)
/dev/fd1h1200 (minor = 9)
/dev/fd1D360 (minor = 13)
/dev/fd1H360 (minor = 13)
/dev/fd1D720 (minor = 17)
/dev/fd1H720 (minor = 17)
/dev/fd1h360 (minor = 21)
/dev/fd1h720 (minor = 25)
/dev/fd1H1440 (minor = 29)
....
The generic floppy devices, _/dev/fd0_ and _/dev/fd1_, will fail to work with *fdformat* when a non-standard format is being used, or if the format has not been autodetected earlier. In this case, use *setfdprm*(8) to load the disk parameters.