David Empson wrote:
I seem to recall there was a modification made to analog controller
board in the Platinum 5.25" drives that allowed them to respond to a ID
request while still essentially being 'dumb' devices
I recall no such feature, and none is required.
The only modification I remember hearing about was a capacitor change in
a DuoDisk to allow it to work on a IIgs without causing problems with
other drives, or something of that nature.
From Tony's site: http://www.apple2.org/A2WebRef/A2Reference05.html
Apparently there was a change to the way the later Smartport firmware
scans the bus, such that ROM03 GS's, IIc+, and LC emulation cards
cannot use drives prior to the Platinum 5.25" drive.