A packet- and circuit-switched communications exchange.

We present a design concept for a communications exchange based on packetized time-division multiplexing. It will support packet-switching of data and circuit-switching of real-time signals, with a wide range of possible bit rate. Key components of the exchange are a central controller and two unidirectional bus loops with attached access units capable of reading and writing addressed information in fixed-format time slots. Circuit switching is achieved by central reservation of slots, following call set-up. Data communications can proceed concurrently without set-up, competing for unused slots.