The Galileo reference troposphere model - a critical analysis

A key card receiver is mounted in the cab of a truck. The driver inserts a card with a power-in contact shorted to several data output contacts. A power-out contact provides power to the receiver to operate three sequentially connected integrated circuits and another integrated circuit for pulsing the three serially connected circuits to convert concurrent binary data of shorted or open conductors on the driver card to a sequential data signal.