Abstract: A new, high capacity switching center for telegraphic lines which employs digital elements is herewith described. The system resembles a multiprocessor with hierarchical organization. The general coordinating functions of the system are carried out by a minicomputer having a main memory and a mass memory. Several high speed microcomputers (known as the multiplex subsystem or multiplexer), each having in turn a local working memory, are interconnected to each other and to the minicomputer through a multiplex channel. Telegraphic lines are connected to each microcomputer. These in turn are linked to users in remote locations. The local memories of the microcomputers include an area reserved for the recording of incoming messages from the connected users and an area for recording the outgoing messages to the connected users. The messages received from one of the various microcomputers are sent to the microcomputer linked with the recipient user by employing the time division multiplex technique (TDM).