BACKUP DEVICE

PURPOSE:To increase the frequency of rewriting and eliminates the need for a battery by sequentially specifying division areas corresponding to the counted value of an address counter part and writing data. CONSTITUTION:The storage area 31 of an EEPROM 3 is divided into (n) and an address counter 32 is provided so as to specifies the divided areas; and data are written in an area corresponding to the count output of the address counter 32. The address counter 32 counts a write signal from a CPU 2 and writes the data in the area corresponding to the counted value each time the write signal is received. The writing is so controlled that the writing of the data to the area becomes uniform. Consequently, when the storage area is divided into (n), the writing can be performed (10,000Xn) times although the frequency of conventional writing is 10,000.