I didn't mean to be too obtuse or discouraging there. I think mostly what I was trying to get across is while just getting the Floppy Emu to work as a 3.5 inch drive for IIgs'es (which should require only very minimal hacking of what you already have) would indeed "add value" for it to really be a must-have peripheral for II emulation it should probably also handle at least one of the other two tasks... and to do those tasks you'll have to make it:
A: Support the "slow" data rate of the IWM, which isn't used on the Mac, and:
B: To do the hard disk/"UniDisk" emulation you'd need to add support for the "SmartPort" protocol, which is analogous to but not the same as the HD-20. (IE, it's a protocol for communicating with "smart" disk devices and uses the IWM essentially as a UART instead of the bits sent and received going directly to a drive read/write head.) This "smart" protocol was necessary for use with 3.5" disk drives on the IIc and IIe because their CPUs/buses were too slow to drive the IWM at the 2mhz necessary for "fast mode". (The "Unidisk" 3.5" drive has an embedded controller board with an MCU on it that ran the disk mechanism at "mac speeds" and buffered the data for the slower II interface.)
Luckily the second part should (hopefully) be relatively easy because a number of open-source implementations of smartport devices already exist. The gotchya with emulating old-fashioned 5 1/4" disk drives is that the function of the control lines is completely different than it is in smartport or 3.5" drive mode. (for the old 5.25" drives they act as raw stepper motor controls, none of that fancy control register stuff applies.) Again, though, open-source implementations exist, so... it's probably *mostly* a matter of porting to your hardware?