| 摘要 |
PURPOSE:To reduce a consumed current by letting a semiconductor memory circuit read data stored in a memory cell at present, compare the data with write data and write only when the data do not agree. CONSTITUTION:When a write data is at an H level and coincident with a data of H level read from a memory cell, an output node 28 of an EX-NOR gate 20 is turned to the H level. The signal and a write signal of L level are inputted to a NOR gate 21. In consequence, an output node 29 of the gate 21 is turned to the L level and the signal is inputted to gates of N-channel transistors 17, 18, with closing a transfer gate. As a result of this, write data are not transferred to bit lines 101, 102, whereby data are not written to the memory cell. A charging/discharging number of times for the bit lines 101, 102 is reduced approximately by 50%, so that the whole consuming power is remarkably reduced. |
