| 摘要 |
PROBLEM TO BE SOLVED: To effectively improve the data maintainability of a nonvolatile storage means. SOLUTION: Data areas A1 and A2 more than one belonging to a first group and data areas A3 and A4 more than one belonging to a second group are set in the nonvolatile storage means. At initial data writing or data reloading with the control operation of a control circuit, the data of the same contents are respectively stored in the data areas A1, A2, A3 and A4 belonging to the first and second groups. For the data stored in the data areas A1. and A2 belonging to the first group, all the plural data bits composing of data are refreshed in a prescribed cycle. Concerning the data stored in the data areas A3 and A4 belonging to the second group, when an error is discovered as a result of a check in each prescribed cycle or after this error is corrected by an error correcting method, only the logical value of the damaged data bit is reloaded with a corrected logical value, but data in the non-damaged data bits are not refreshed but remain as they are. |
