The Apple IIGS is designed to be used with the vast majority of Apple IIe
hardware and software. However, there are some design differences that will
cause some products to be incompatible with the Apple IIGS.
A number of communications packages written for the Apple IIe bypassed the
firmware available for the system. Those software programs that write
directly to the IIe hardware cannot be used on the Apple IIGS, since the
serial ports are now controlled by a 8530 Serial Communications Chip, rather
than a 6551. Most currently available communications packages, including
Access II, version 1.1, do not work on an Apple IIGS.