A transponder assembly for use with fiber optic digital communication cables having multiple parallel optic fiber elements. The transponder assembly features a transmitter port and receiver port for connection with separate parallel optic cables for separately transmitting and receiving data and an electrical connector for connecting with computer or communication systems. The transponder assembly includes a parallel optic transmitter module and a parallel optic receiver module having pluggable edge connectors. The assembly also includes a circuit board on which a semiconductor chip useful for signal processing and the electrical connector are mounted. A flex circuit is used in connecting the circuit board to the parallel optic modules. The semiconductor chip and electrical connector are mounted directly across from one another on opposite surfaces of the circuit board.