Abstract: A single button contrast control which can bi-directionally adjust a contrast function in one of two directions so as to increase or decrease the contrast of a display. An interrupt generator generates an interrupt for each user activation of a single button control key. A control circuit incrementally adjusts the contrast function in accordance with the interrupts generated. If no interrupts are generated within a predetermined period of time following a previous interrupt, the control circuit changes the direction in which the contrast is incrementally adjusted so that the next time a user activates the single button control key the control will be adjusted in the other direction.

Abstract: A peripheral device operatively coupleable to a computing system which includes a processor for processing various functions relating to the operation of the peripheral device. The peripheral device also including a memory operatively coupleable to the processor, the memory storing a device driver which the computing system employs to communicate with the peripheral device.

Abstract: A portable electronic device including a portable housing; electronic circuitry within the housing, the electronic circuitry being operable to perform functions independent of and in combination with a system backbone including at least one of an Ethernet backbone and a Token Ring backbone; and an internal area network (LAN) controller within the housing for serving as an interface between the electronic circuitry and the system backbone.

Abstract: A secondary battery boost system which includes a primary power supply for a computing device, and a secondary power supply for the computing device. The boost system also includes a boost circuit operative to increase the power output of the secondary power supply applied to the computing device. Upon the output of the primary power supply falling below a level suitable for properly powering the computing device, the boost circuit feeds the computing device power from the secondary power supply. The boost circuit also boosts the power output of the secondary power supply so that the secondary power supply can be smaller and more light weight.

Abstract: A circuit for energizing an electroluminescent panel of a portable data collection device is disclosed. The circuit includes voltage step up circuit and a switching circuit. The voltage step up circuit converts a +5 volt DC signal output from power regulation circuitry of the portable data collection device to a +100 volt essentially constant DC signal. The voltage step up circuit includes a switching regulation integrated circuit chip coupled in series to a toroid inductor. The inductor is coupled through a diode to a smoothing capacitor. The switching circuit converts the +100 volt DC signal to effectively a .+-.100 volt (200 volts peak-to-peak), 500 Hertz (Hz) signal across electrodes of the electroluminescent panel. The switching circuit includes a 555 IC timer chip coupled to an H bridge configuration of switching transistors.