| 摘要 |
<p>PROBLEM TO BE SOLVED: To prevent rewriting from exceeding the number of rewriting times of EEPROM in a semiconductor memory provided with an electrically erasable programmable ROM (EEPROM). SOLUTION: A counter 11 counts the number of rewriting times in each memory cell in an EEPROM 10 from an address (Address) and a write-enable signal (Write Enable/), when th number of times of rewriting reaches the limit in either of memory cells, a warning signal OVF is generated. When the warning signal OVF is generated an OR gate 12 set forcibly a level of a write-enable signal (Write Enable/) to the EEPROM 10 to invalid 'H' level. Thereby, rewriting in the EEPROM 10 is prohibited.</p> |
