Electronic telephone switching system comprising a speech path switching

Abstract

An electronic telephone switching system is described having peripheral units including a plurality of subscriber and line circuits, a plurality of trunk and tie line circuits, at least one attendant line circuit, a plurality of signaling tone receivers, and a plurality of link control circuits. Switching is carried out by a one wire speech path switching matrix and a one wire tone switching matrix. The system is centrally controlled and includes a central processing unit, a program memory, a scratch pad memory and a customer memory. Information, commands and addresses are communicated between the peripheral units and the central control and within the central control via bus lines. The bus lines between the peripheral units and the central control transmit data with lower rise time pulses than the bus lines interconnecting the components of the central control. Each electronic crosspoint switch has a two terminal conducting path and a control terminal for controlling the state of conduction of the conducting path. Different conducting path terminals of the speech path matrix and tone path matrix crosspoint switches are operated by the same peripheral link unit. The matrix coordinates to be operated are defined by polling the different peripheral units connected to the coordinates in question.