US Patent 7411840 Sense mechanism for microprocessor bus inversion

A sense mechanism for data bus inversion including a first memory device and an analog adder. The first memory device stores bits of the bus in a previous bus cycle. The analog adder compares the bits of the bus in the previous bus cycle with bits of the bus in a current bus cycle and provides a data inversion signal indicative of whether more than half of the bits of the bus have changed state. The analog adder operates as a bus state change sense device which rapidly evaluates bus state changes from one bus cycle to the next. The data inversion signal is used for selectively inverting the data bits of the bus and indicating bus inversion according to data bus inversion operation, such as according to X86 microprocessor protocol.