Asynchronous time division multiplex switching network for multi-service digital network. It comprises a plurality of time division multiplex bidirectional highways, a plurality of data transmit and receive stations connected to and associated with said bidirectional highways and a plurality of buses...http://www.google.com.hk/patents/US4446555?utm_source=gb-gplus-share專利 US4446555 - Time division multiplex switching network for multiservice digital networks
