Abstract: An improved optical card reader is disclosed which is adapted for use with processing means for providing on-the-fly decoding of multibit data words from a card that is inserted therein. The card reader has two sets of light emitting means and two sets of light detecting means and the light detecting means are interconnected to provide a single set of outputs to comparators which measure the signal levels and provide distinct digital outputs. Selective energization of the light emitting means provides effective multiplexing of two multibit data words from a single set of outputs.

Abstract: A battery backup system provides DC power to a data processing system in the event of an AC power failure. A preferred embodiment supplies DC power from a plurality of series-connected batteries at a voltage level sufficient to operate a data processor. After a time delay, the batteries are connected in parallel to provide DC power at a lower voltage level sufficient to maintain information stored in a memory.