Abstract: A system bus expansion which guarantees the coupling of multimaster-capable multicomputer systems and acts as an interface between spatially separated but mutually disposed system components. The expansion includes a separate expansion module, serving as a receiver and transmitter of addresses, data, commands, and status signals, assigned to each of the system buses that is to be coupled. These expansion modules are connected by a cable. The transmission is effected without changes, so that the two bus sides form a logical unit, and this unit, as well as each side by itself, remains multimaster-capable.