| 摘要 |
PROBLEM TO BE SOLVED: To surely reproduce correct backup data after a main power source is restored even when a main power source is disconnected during the writing of backup data in a memory. SOLUTION: When first and second writing signals 21A and 21B are successively turned into a low level, data are written in first and second memories 18 and 20, and the signal level of the first writing signal is held by a signal level holding part 26. When a main power source is disconnected, and the signal level of the first writing signal indicated by the output signal of the signal level holding part 26 after the main power source is restored is a low level, a memory selection controlling part 22 instructs the reading of data only to the second memory 20 when a reading signal 12 is supplied, and when the signal level of the first wiring signal indicated by the output signal of the signal level holding part 26 after the main power source is restored is a high level, the memory selection controlling part 22 instructs the reading of data only to the first memory 18 when the reading signal 12 is supplied. |
