An experimental space-division telephone exchange

A description is given of an electronic telephone exchange employing p-n-p-n transistors as switching elements at the cross-points of a space-division system, and the method whereby this type of p-n-p-n network is controlled for setting up a connection is explained. The paper concludes with a short description of the control equipment used, such as the information distributor, the marker, the number translator, the central register and inventory memories.