Abstract: A printed circuit board assembly having a first main printed circuit board and a connector connecting to the main board. A subsidiary board connects to the connector. The main board has a plurality of socket holes and the connector has a corresponding plurality of pins. The invention overcomes the problem of the prior art assembly, which requires a different main board to accommodate each type of connector having a different pin spacing. The main board of the invention has a combination group of four rows of holes, including a first row of holes and a third row of holes having a same first lengthwise spacing which receive the pins of one type of connector and including a second row of holes and a fourth row of holes having a same second lengthwise spacing which receive the pins of another type of connector. The first row of holes respectively having a first set of outer conductors. The first row of holes also respectively have a first set of inner conductors.

Abstract: A recorder of the states of a traffic control system which stores and visually displays the current operational state of the system. The current states of the command signals produced by the traffic controller of the system and the current states of energization of each traffic signal light, after a predetermined delay, are stored in a bistable device. The occurrence of an error, conflicting or improper timing of the energization of the traffic lights of the system or of the command signals controlling the energization of such lights are sensed by a conflict monitor. Upon the occurrence of an error, the bistable devices are latched, i.e. prevented from thereafter changing state. The state of each bistable device is visually displayed as of the occurrence of an error.