Somehow that just doesn't sound right to me, search around a bit for the "Developer Note" for both systems. IIRC the DOS Compatibility Cards/DOS versions of systems have their own DevNotes as well.
edit: didn't find anything at my usual haunt: http://cdn.preterhuman.net/texts/computing/apple_hardware_devnotes/
edit: didn't find anything at my usual haunt: http://cdn.preterhuman.net/texts/computing/apple_hardware_devnotes/