| 摘要 |
<p>PURPOSE:To shorten the rewriting time when the information stored into a nonvolatile semiconductor memory electrically enabling to write in and erase information has a part frequently rewritten and a part, not rewritten. CONSTITUTION:A memory array 1 of a flash EEPROM is divided into two and the memory cell in the sector 1a in the one side is made en block erasable and the memory cell in the sector 1b in the other side is made en block unerasable. Since a part being frequently rewritten is programmed in the en block erasable sector 1a and the unwritten part is programmed in the en block unerasable sector 1b, the unwritten part is erased and reprogramming is unnecessary, then the rewriting time is shortened.</p> |
