A DB-19 female connector, the drive port on the back of the Apple IIGS is
commonly refered to as the 'SmartPort'. Actually 'SmartPort' is a set of
assembly language routines used to support block I/O devices. The 'SmartPort'
firmware includes the Protocol Converter software used in the Apple IIc 3.5
ROM revision. Up to six drives (DuoDisk, Uni-Disk, Uni-Disk 3.5, Apple 5.25
Drive, Apple 3.5 Drive are all plug compatible with port) may be attached to
the port at any one time.