Channel selection in Highgate Wood electronic telephone exchange

In the Highgate Wood electronic telephone exchange, external lines connect to time-division-multiplexed channels on group highways and thence, via coincident channels on further highways, to either the register or other lines on the exchange. The channel selector completes such connections singly by selecting the channel to be used and sending the channel pulse to the appropriate connection memories. This equipment serves all the exchange lines and operates at high speed to provide the required grade of service.