Origin of diplexaltered (after di-) ; from duplex
Origin of diplexdi–1 + (du)plex.
diplex - Computer Definition
A circuit or device that supports simultaneous transmission or reception of two independent signals. Diplex communications technology is a simple form of multiplexing that was considered quite revolutionary in the early days of telegraphy, when a diplex circuit would support transmission of two independent signals in one direction only. The term continues to be used in radio communications. See also quadraplex and multiplexer.