US Patent 9083327 Semiconductor device and method of driving semiconductor device

A novel semiconductor device and a method of driving the semiconductor device. A (volatile) node in which data that is rewritten as appropriate by arithmetic processing is held and a node in which the data is stored are electrically connected to each other via a source and a drain of a transistor in which a channel is formed in an oxide semiconductor layer. Then, data and data obtained by inverting the data (inverted data) are stored before supply of power source voltage is stopped, and the two inputs (data) are compared after restart of supply of the power source voltage, so that data obtained by arithmetic processing just before the supply of the power source voltage is stopped is restored.