SEMICONDUCTOR MEMORY DEVICE

摘要

PURPOSE: To contrive a low dissipation of power by avoiding useless power consumption of a semiconductor memory device. CONSTITUTION: A selecting circuit 2 selects the specified memory cell of a memory cell array 1. A reading circuit 3 reads out the data of the selected memory cell. A writing circuit 4 writes the data into the selected specified memory cell. A first control circuit 5 reads the data out of the selected memory cell by controlling the reading circuit 3 in the same cycle of a clock signal and then writes the data to be read at the next time into the selected memory cell by controlling the writing circuit 4. A comparing circuit 6 compares the read-out data of the selected memory cell and the writing data. A second control circuit 7 prohibits the writing of the data to be written into the selected memory cell by nullifying the control of the writing circuit 4 with the first control circuit 5 when it is judged that the read-out data and the writing data are same from the result of the comparison with the comparing circuit 6.