Abstract: A modular system for controlling the routing of data through a plurality of data terminals includes a number of modules in a tree structure. Each of the modules has circuitry for receiving a data stream. Each of the modules further has a plurality of ports, each port being suitable for transmitting data to and receiving data from data devices such as data terminals and other modules. Each of the modules includes a routing array connected to the ports for serially connecting the ports for flow of the data stream through the operable data devices connected to the ports. The routing array is internally controllable to open a selected one of a plurality of data paths between the ports. At least some of the ports have driver circuits associated therewith for regenerating and converting the data stream as it passes between ports in the selected data path. Each module has an output for supplying the data stream from the module to a destination device.