Bidirectional

Communications mode that is capable of transmitting data in both directions, but not at the same time. Bidirectional is also a printer port mode that was first introduced by IBM in 1987 with their introduction of the PS/2 computer.

The bidirectional port is an 8-bit port capable of transmitting between 75 and 300 KBps that was available as either a Type 1 or Type 3 port, which used a DMA.

Also see: Parallel port, Printer definitions, Unidirectional