SYNCHRONOUS TIME-SHARED DATA BUS SYSTEM

摘要

A data bus system includes a plurality of interconnected active terminals, i.e., terminals which receive data from one terminal and retransmit it or transmit new data to another terminal. The data is in serial digital form and is transmitted within a continuous series of time frames of predetermined length with each time frame being initiated by a control word transmitted by one of the terminals designated the controller terminal. Each terminal includes a counter which counts the bits between control words, and each control word includes an identification of the controller terminal so that each terminal can synchronize its counter with the counter at the controller terminal in accordance with the propagation time of data from the controller terminal. Logic circuitry is provided at each terminal so that one of a plurality of terminals can assume the function of the controller terminal should the presently designated controller terminal fail to generate control words to define the time frames. Within each time frame various of the terminals initiate data at appropriate times in accordance with the count on the counter of the initiating terminal, and the transmitted data is coded with the identification of the receiving terminal or terminals which are to direct the data to users tied in to those terminals.