Updated: 06/30/2019 by Computer Hope
standard parallel port

Alternatively referred to as SPP (Standard Parallel Port), unidirectional refers to data either sent or received in one direction. For example, the parallel port on a computer can be unidirectional, allowing the computer to send data to a printer, but not allow that printer to communicate back.

Unidirectional ports were found on computers manufactured before 1995, capable of transmitting data 4-bits at a time, at 40 to 60 KBps over a six foot cable. This standard was later moved into the IEEE-1284, updated, and now known as Centronics mode.

Unidirectional may also describe a type of microphone that is only capable of picking up sound in one direction.

Bidirectional, Centronics mode, Parallel port, Printing terms