A parallel interface modem for simultaneous transfer of a plurality of parallel signals across a medium is disclosed. In a preferred embodiment, the parallel interface modem includes a modulation circuit for qualifying each of the plurality of parallel device interface signals for serial transmission. Each of the plurality of qualified signals substantially simultaneously accumulates at a summing junction responsive to the modulation circuit. A mixer communicating with the summing junction combines the plurality of accumulated qualified signals to provide a multi-frequency signal. A serial port connector communicating with the mixer simultaneously transmits the plurality of accumulated qualified parallel device interface signals over the medium.Additionally, the parallel interface modem includes a demodulation circuit communicating with the serial port connector demodulating each of a plurality of received signal forming a multi-frequency parallel device interface signal received from the medium.