The DuoDisk usually acts like two Apple 5.25-inch drives. There are a
couple of compatibility issues, however:
* If you plan to attach the DuoDisk to the SmartPort on the back of the
Apple IIGS, and it is going to be the last device in the chain, then you
need to make sure the DuoDisk's analog board has a particular
modification. If it lacks this modification, you can do it yourself.
Details can be found in both "Tech Procedures for the DuoDisk" and the
Product Notices section of the "Apple Service Programs" binder.
* If you have a newer IIGS, with rev 03 ROMs and 1MB of RAM installed on
the logic board, you CANNOT attach the DuoDisk to the SmartPort at all:
you must use a DuoDisk interface card, just as if the IIGS were an
Apple IIe instead. You can buy this through Service (part number
661-92131).
If you meet these two considerations, the DuoDisk will not affect your
other attached disk drives.