STORAGE DEVICE USING EEPROM

摘要

PURPOSE:To carry on a due work process with no loss of information by using plural recording EEPROMs including the spare one and using this spare EEPROM when the frequency of use reaches a prescribed limit level. CONSTITUTION:A recording EEPROM 1 and a spare EEPROM 2 are prepared and the ROM 2 backs up the ROM 1 as a spare one. An erase/write means 3 applies an erasing or writing operation to the ROM 1 and store its frequency of use each time into a use frequency storage means 4 set in a prescribed area of the ROM 1. When the frequency of use stored in the means 4 reaches a prescribed limit level, the working EEPROM is switched to the ROM 2 from the ROM 1 via an element switch means 5 and an erasing or writing operation is carried out. As a result, the frequency of use is controlled with no loss of information and the automatic switching is performed between the ROM 1 and the ROM 2. Thus a due process can be carried on.