| 摘要 |
PURPOSE:To prevent a device from being used by a malfeasant user by preventing a program content from being read out normally, preventing the address of a CPU from coinciding with that of program memory as for the address of a program until the switching destination of a bus is analyzed, and disabling the analysis of the program. CONSTITUTION:A sensor 1 is the one to discriminate whether or not a third party handles the device malfeasantly, and when a malfeasant signal which shows the fact that device is handled malfeasantly is inputted from the sensor 1, a bus switching circuit 2 switches a bus signal. Also, the program content is read in the CPU 4 normally from a ROM 3 in memory in which the program is written via a bus signal pattern 5 and the bus switching circuit 2 ordinarily. However, when the device is handled malfeasantly, the bus signal of the address of the program is switched by the bus switching circuit 2, therefore, noncoincidence between the address of the CPU 4 and that of the ROM 3 is obtained, thereby, no normal read-in of the program in the CPU 4 is performed. |
