The SP516 is a monolithic device that supports eight (8) popular serial interface standards for DTE to DCE connectivity. The seven (7) drivers and seven (7) receivers can transmit and receive signals over 20Mbps. The SP516 requires no additional external components for compliant operation for all of the eight (8) modes of operation. All necessary termination is integrated within the SP516 and is switchable when V.35 drivers, V.35 receivers, and V.11 receivers are used. The SP516 can operate as either a DTE or DCE. Additional features with the SP516 include internal loopback that can be initiated in either single-ended or differential modes. While in loopback mode, driver outputs are internally connected to receiver inputs, creating an internal signal path convenient for diagnostic testing. This eliminates the need for an external loopback plug. The SP516 includes a termination network disable pin for the V.35 and V.11 receiver input termination circuitry. High-Z ability for the driver and receiver outputs is controlled by supplying a 4-bit word into the address decoder. Seven (7) drivers and one (1) receiver in the SP516 include separate enable pins for added convenience.