Why is the Apple M0131 external 3.5" floppy "HFS only"?

I don't see why it would matter (and if anything, it's the 'wrong way round for it to matter') but IIRC, the 800K drive sets the spindle speed autmattically depending on which cylinder tis's on, the 400K drive takes a PWM speed control signal from the Mac mainboard. There are some oddiites in the floppy cabling, to the extnt that the internal drive ribbon cables have 1 or 2 wires missign (solid plastic). I think that a pin that's a power line (-5V?) on the logic board is 'remote eject' at the drive. But that couldn't be fixed with software, so that can't be it. Have tyou tried it? Given that it can be made to work on the Mac 512 with software chages (new ROMs or an OS extension), I don;t think plugging it in will do any damage. -tony