From the "why not" department:
PS/2-mode floppy controllers have a RDDATA bit in the SRB status register, which essentially samples flux transitions incoming from the drive (each transition toggles the flip-flop and its output is the RDDATA).
"MX:" is the format used by floppy controller on Soviet PDP-11 compatible desktops (the DVK series). Low level encoding is FM, and track format is not compatible with IBM 3740 -- http://torlus.com/floppy/forum/viewtopic.php?f=19&t=1384
) is a DOS program written by Vladimir Poletaev in 1997 to recover data from such floppies on a Pentium-class PC. And with a bit of hacking, it works in MAME (at least some of the time):
PR coming soon.