Abstract: A switching system for connecting a plurality of input signals to a pluray of selected outputs. A plurality of input signals are connected to a crosspoint matrix through a buffer circuit. The crosspoint switching matrix is comprised of a plurality of CMOS crosspoint switch integrated circuits and switching is controlled by a microprocessor which provides the desired connections for selected outputs. A built-in-test circuit (BITE) is provided for testing each circuit path in the switching system.

Abstract: A closed loop system for communication of binary data utilizes master or a sources and slave or data sink stations, each including a transmit buffer, a three-state transmitter, a receiver, a comparator, a three-state receiver, a receive buffer, a timer, a filter and a local controller, with the transmitter of each station connected by a transmission path to the receiver of the other station. Binary data bits are separated by spaces and bits and spaces are transmitted singly from the source station, received and retransmitted back to the source station by the sink station, with each retransmitted bit or space being compared at the source station with its original transmission for verification before a succeeding bit or space is transmitted.