Abstract: A backplane apparatus provides board address information for each board inserted in the slots of the backplane, using a single pin in the backplane slot. A unique address for a board in a backplane slot is identified by an analog address signal, which can be communicated on a single line and therefore requires only one pin in the backplane slot or in the device which will read the address information. The analog address signal is a function of a component, such as a resistor or a capacitor, coupled to the address pin in the backplane slot. A predefined characteristic of the component, such as the resistance or the capacitance, is unique for each slot. The component characteristic is converted into a corresponding characteristic of the analog address signal, such as the voltage, current, frequency or the slope of a voltage or current ramp, so that the analog address signal is measurably different for every slot.

Abstract: A load test board is configured for plugging into a backplane of a chassis. The load test board has a CPU, a variable load controlled by the CPU, a voltage sensor to detect voltage across the variable load, and a current sensor to detect current through the variable load. To test the chassis, one or more of the load text boards are plugged into the backplane of the chassis. Each load test board provides a variable load, using circuitry on the test board to control the variable load, and measures current through the variable load and voltage across the variable load. Information corresponding to the measurements is conveyed to a host computer.

Abstract: A computer controlled system has two or more secondary backplanes that are plugged into slots in a primary backplane. Board slots in the secondary backplanes are assigned unique addresses, and the range of addresses for each secondary backplane is contiguous with the range of addresses for a neighboring secondary backplane. Each slot in the primary backplane has one or more primary address pins. The primary address pins in the primary backplane slots are coupled so as to set the primary address pins in each primary backplane slot to a unique value. Each secondary backplane has a bus line for each primary address pin of the primary backplane slot into which it is plugged. The bus lines couple the primary address pins to board address identification pins, also called address pins, in certain of the board slots. Address pins are provided for each board slot, and are set to selected values for each board slot.

Abstract: A method for monitoring current in a power supply system including multiple parallel power supplies and current load sharing devices for each power supply. The error voltage generated by the current load sharing devices, in the process of balancing the power supply outputs, is proportional to current provided by a single power supply. The total number of power supplies may be determined by including a small current source with each power supply, and using the current sources to drive a “present” line, the current on this line indicating the number of power supplies present. The error voltage and the present line signal are used by a control circuit that includes analog-to-digital conversion and a CPU to calculate the total current drawn by the supply, and to trigger a circuit breaker if the total current exceeds a predetermined limit.

Abstract: A microcontroller generates a digital signal in response to input data, such as temperature and/or fan speed data. The digital signal is converted to an analog signal that is used to control a variable power supply. The variable power supply outputs a regulated substantially constant output voltage at a voltage level corresponding to the value of the digital signal. The analog signal is produced by a resistor divider and a feedback adjustment circuit that includes a plurality of resistive elements that are selectively coupled in parallel with a portion of the resistor divider in response to the digital signal. The resistive elements coupled in parallel with the portion of the resistor divider adjust the voltage generated at the resistor divider's center node. The voltage on the center node is the analog signal that is used to control the variable power supply.

Abstract: An integrated packet switching and circuit switching system comprising a number of switching modules each connected to a corresponding plurality of user terminals. Each switching module includes a time-slot interchange unit for providing circuit-switched communication channels and a control unit that controls the operation of the time-slot interchange unit. Each switching module also includes a packet switching unit used both to provide packet-switched communication channels among the user terminals connected to that switching module, and to switch control information between the user terminals and the control unit to establish circuit-switched calls and packet-switched calls. A time-multiplexed switch interconnects the switching modules to provide circuit-switched communication channels and packet-switched communication channels between user terminals of different switching modules.

Abstract: An integrated packet switching and circuit switching system comprising a number of switching modules each connected to a different plurality of user terminals. Each switching module includes a time-slot interchange unit for providing circuit-switched communication channels and a control unit that controls the operation of the time-slot interchange unit. Each switching module also includes a packet switching unit used both to provide packet-switched communication channels among the user terminals connected to that switching module, and to switch control information between the user terminals and the control unit to establish circuit-switched calls and packet-switched calls.