| 摘要 |
<p>PROBLEM TO BE SOLVED: To improve the security of stored information while keeping satisfactory rewriting operability for an electrically erasable and writable non-volatile memory on-chipped in a data processor. SOLUTION: The erasable/writable non-volatile memory has a first domain (12) and a second domain (11). A mode setting circuit (8) can set a first operating mode (PROM writer mode) for allowing erasing/writing in the first memory domain by connecting a PROM writer to the data processor. A domain (16) is located for storing security information for setting secrecy protection to the first domain. Even in a secrecy protecting state, a CPU (2) allows the writing after all erase to the first domain in the first operating mode. When allowing the rewriting in the first operating mode during the secrecy protecting state, the first domain is accompanied with all erase, so that secrecy protection can be improved.</p> |
