Abstract: An apparatus for controlling the illumination of two diode indicator lights with a single control line. The apparatus includes a circuit adapted to selectively provide one of high, low and medium voltage levels on a control output line responsive to combinations of high and low DATA and ENABLE signals. A first indicator is provided having a first diode with an anode and a cathode, the cathode being operatively connected to ground. A second indicator is provided having a second diode with an anode and a cathode, the cathode being operatively connected to a source of medium level voltage. A current limiting resistor is provided having a first end operatively connected to the anode of each of the first and second diodes, the opposite end thereof being connected to the control output line. Moreover, a pull-up resistor is provided having one end connected to the control output line and an opposite end connected to the medium level voltage source.

Abstract: A display apparatus for selectively and independently controlling the illumination of two diode indicator lights with a single control line. The apparatus includes first and second diode indicator means connected in parallel with one another, with the cathode to anode direction of the first diode indicator means being opposite the second diode indicator means. A circuit means is provided which is adapted to selectively provide one of high, low and medium voltage levels on a control output line responsive to combinations of high and low DATA and ENABLE signals. One of the first and second diode indicator means being switched on when the output line voltage level is high, the other being switched on when the voltage level is low and neither indicator means being switched on when the voltage level is medium.