| 摘要 |
<p>PURPOSE:To prevent the generation of defective data reading by selectively supplying either one of 1st and 2nd operation voltages to a memory and comparing data read out of the memory to which the 1st or 2nd operation voltage is supplied with data to be stored. CONSTITUTION:At the time of writing data, the data to be stored are written in a non-volatile memory 21 and simultaneously written also in the other memory 22. When the 1st voltage smaller than normal operation voltage is supplied to the memory 21, the data are read out of the memory 21 and compared with the data stored in the other memory 22 and whether both data match with each other or not is checked. When the 2nd voltage larger than the normal operation voltage is supplied to the memory 21, the data are similarly read out of the memory 21 and compared with the data stored in the memory 22 and whether both data match with each other or not is checked. In any case, the complete match of both data is confirmed. Consequently, the generation of defective data reading due to the variation of the power supply voltage can be previously prevented.</p> |
