Abstract: A circuit composed of a circuit board of crystalline elemental silicon slice and circuit components in the form of semiconductor integrated circuits therein which are preferably formed of a Group III-V compound. Signals from each of the integrated circuits are transmitted to other integrated circuits on the board or externally of the board either by conventional printed conductors on the board or by a laser formed in each integrated circuit at each output terminal thereon which transmits light signals along light transmitting members in the silicon board to detectors at the input locations on other ones of the integrated circuits on the board for external to the board. The light signal is transferred from an integrated circuit output to an integrated circuit input or to a device external to the board by means of light transmitting members. These light transmitting members may be light conducting waveguides positioned either on the surface of the board or in grooves formed therein.