Abstract: A multiplexing circuit uses parallel-configured switch/resistor pairs in a voltage divider network in such a way that a single analog-to-digital input can be used to specify the state of more than one switch or other component. One circuit includes a reference voltage node, a ground node, and an output node, wherein a switched voltage divider network is configured such that the voltage at the output node is unique for every given combination of switch states.

Abstract: A power source management system disposed within a device is configured to communicate with a power source and perform an authentication procedure to determine whether the power source is an approved power source. The authentication procedure may involve the use of a challenge-response procedure using keys resident in the device and the power source. If it is determined that the power source is not an approved power source, the power source management system prevents use of or disables certain functionality of the device.

Abstract: A multiplexing circuit uses parallel-configured switch/resistor pairs in a voltage divider network in such a way that a single analog-to-digital input can be used to specify the state of more than one switch or other component. One circuit includes a reference voltage node, a ground node, and an output node, wherein a switched voltage divider network is configured such that the voltage at the output node is unique for every given combination of switch states.

Abstract: A hybrid power supply used in a device generally includes a fuel cell plant configured to produce a DC voltage via electrochemical conversion of a fuel, a fuel reservoir attached to the fuel cell plant for supplying the fuel to the fuel cell plant, and a rechargeable battery electrically coupled to the fuel cell plant. The fuel cell plant keeps rechargeable battery substantially charged while rechargeable battery accommodates load variations resulting from operation of the device. In this way, the hybrid power supply maintains operation of the device when the fuel reservoir is removed.

Abstract: Apparatus and method for managing the availability of items using a computer system. The system permits various computers to access databases located at offsite computers to retrieve/transmit preselected information pertaining to the availability of items from/to each accessed database. Categories of items are selected by a user prior to communicating with offsite computers so that only the categories of interest are selected and only data pertaining to those categories is downloaded to the requesting computer or uploaded from a called computer. Once data has been retrieved by the requesting computer, the user can use various parameters to select and display the received information in the selected categories. In addition, the requesting computer can automatically retrieve information from offsite computers at a predetermined time each day of the week.