Abstract: A method and apparatus for serial communication of digital information in an information processing system for high throughput fault tolerant communication is disclosed. High throughput is achieved by providing a multiplicity of communication circuits, which are preferably four-wire, full duplex bidirectional channels for serial communication of digital information, and by providing full duplex, bidirectional communication of messages at a first rate and half duplex, unidirectional communication of large blocks of data at a second higher rate over the communication circuits. Fault tolerance for serial communication of digital information is provided by the multiplicity of communication circuits so that if one communication circuit is inoperative the remainder of the communication circuits is available for communication.