| 摘要 |
PURPOSE:To hold the secrecy of storage data by inputting a code in addition to the address of the data stored in a memory. CONSTITUTION:When a custom code is written in a custom code register 3, a write signal X is outputted from the custom code register 3, and stored in a reload preventing circuit 4. The write signal X is stored, and a write prevention signal Y outputted from the reload preventing circuit 4 is turned to '0', and inputted to an AND circuit 5. There after, even when '1' indicating a write mode is inputted to the AND circuit 5, the output of the AND circuit 5 is turned to '0' and the writing in the custom code register 3 is enabled. And also, when only the address of the objective storage data is inputted, and the custom code is not inputted, the normal level of a bus C is different from a held custom code D, and then the address different from the inputted address is outputted from an address conversion circuit 6. |
