| 摘要 |
<p>PURPOSE:To perform minimum required number of erase operations and write operations by selecting a bit for which the erase operation and the write operation must be performed from the content of present storage data and that of data desired to store from now. CONSTITUTION:A gate line voltage setting part 105 outputs VPP potential and next, GND potential, and a data line voltage setting part 101 outputs the VPP potential or the GND potential corresponding to the logical values of read out data O0-O3 and supplied data D0-D3. In other words, the bit for which the erase operation must be performed and the bit for which the write operation must be performed are selected from the combination of the logical value of the data already stored in a designated address and that of designated data, and only a selected bit for which the erase operation must be performed is erased, and a selected bit for which the write operation must be performed is written. In such a way, all the meaningless erase and write operations according to a rewrite operation can be eliminated, and the rewrite operation can be completed by the minimum required number of erase operations and write operations.</p> |
