The floppy disk drives are interfaced through a Fujitsu 8877 disk controller integrated circuit, a second-source of the Western Digital 1793. The parallel port is connected through a memory-mapped Motorola MC6821 Peripheral Interface Adapter (PIA) which allows the port to be fully bidirectional; the Osborne manuals claim that the port implemented the IEEE-488 interface bus but this is rarely used. The parallel port use a card-edge connector etched on the main board, exposed through a hole in the case; any IEEE-488 or printer cable has to be modified for the Osborne.