| 摘要 |
PROBLEM TO BE SOLVED: To securely perform a block change before the data holding period of the specification of a flash memory passes, in performing EEPROM emulation by the flash memory incorporated in a semiconductor device, as the flash memory has the data holding period shorter than the EEPROM and manages data by block unit.SOLUTION: For an EEPROM substitution area in a flash memory, a data level check voltage is set between an internal verification voltage and a read-out voltage. When data level becomes below the data level check voltage, the block change is performed. |
