Ok.

The native Amiga hardware can do nearly anything, as the bit/byte
encoding is done by software.

currently supported formats are:

- Amiga native,	with 11 (or 22) sectors @ 512 bytes each per track	(fdNa)
- IBM,		with 9 (or 18) sectors @ 512 bytes each per track	(fdNb)

interleave has no influence on performance, as we always read a full
track of bits, decode it to block buffers, use them as long as possible, 
and encode & write them back when the track is changed and some of the
block buffers are dirty.

The canonical lowlevel formatter for NetBSD-Amiga with native floppy hardware
is just 

dd if=/dev/zero of=/dev/rfdNa bs=22 count=80	or
dd if=/dev/zero of=/dev/rfdNa bs=18 count=80

or variations for HD disks.

Regards,
	Ignatios