Abstract: A novel high speed unidirectional bus system is provided for receiving a plurality of novel circuit card assemblies in receptacles on the bus. Adjacent receptacles are connected by lines on the bus which interconnect output pins to input pins. The circuit between output pins and input pins are formed by connecting the plugs on circuit card assemblies into the receptacles on said bus. The system comprises a plurality of function circuit card assemblies connected in a daisy chain when inserted into adjacent receptacles on said bus between a source circuit card assembly and a destination circuit card assembly and the address portion of the information supplied by the source circuit card assembly is programmed to identify the function circuit card assembly to first receive the source data whereby the unidirectional bus system may be operated in a time division random access mode at data rates in excess of the data rates of individual functional circuit card assemblies.