Abstract: A multiplicity of independently operating miniprocessors of an electronic data-processing system are grouped in a number of subsystems each including an individual control unit for carrying out an exchange miniprogram, upon request by an originating miniprocessor of its own subsystem, involving a series of data transfers between a transmitting and a receiving miniprocessor of the same or of a different subsystem. The control unit assigns to each exchange request a certain priority level, determined by the time of arrival of the request and by the location of the originating miniprocessor, and establishes an order of precedence in which data blocks are transferred between different pairs of miniprocessors in a time-division mode.