Abstract: An electronic step-by-step switching system utilizes much of the equipment now present in conventional electromechanical step-by-step telephone exchange switches. Conventional line finders, selectors and connectors are modified by removing the relay logic and replacing it with microprocessor based controllers. The modified line finders communicate through a bus with an originating controller and the modified connectors communicate through a bus to a terminating controller. The controllers are interconnected for data exchange through high speed buses that are supervised by a bus controller. A programmer station is installed for bi-directional communication through the bus controller. The originating and terminating controllers include memory storage for maintaining status information concerning the subscriber lines within the groups of corresponding line finders and connectors. The modified line finder works in conjunction with the originating controller to identify the line for an off-hook subscriber.

Abstract: An improved step-by-step switch assembly includes an electronic controller conversion module. A programmed microprocessor responds to incoming pulse trains of widely variant make and break ratios and generates precisely timed and shaped pulses to operate vertical, rotary and release magnets of the switch assembly. Other features include increased loop sensitivity, selective digit absorption and automatic periodic contact wiping to clean all of the contacts of the assembly.