| 摘要 |
PURPOSE:To protect the contents of a memory to which a user's access is not permitted by executing execution suspension of a program or memory access inhibition, in the case where a mode conversion for reading out the memory contents to which a user's access is not permitted is detected in the course of executing the program. CONSTITUTION:In a storage area 2, a RAM and other area 24 to which a user can execute an access and a ROM area 21 in which an OS, etc., are stored, are subjected to mapping. In the ROM area 21, an address of an interruption or reset time processing program 23 is stored in an interruption vector and reset vector 22. In such a state, in a storage area for mapping a memory to which an access of a ROM, etc., is not permitted in a first execution mode, in the case where a conversion to a first execution mode is detected in the course of executing the program in a second execution mode for mapping the memory to which the user can execute an access, a signal for suspending the execution of the program such as an interrupting signal, a reset signal, etc., is generated, and it is avoided to read out the contents of the memory to which a user's access is not permitted. |
