| 摘要 |
<p>PROBLEM TO BE SOLVED: To easily ensure a security of a program in a ROM externally installed. SOLUTION: An address outputted from CPU which outputs an address of a command to be executed, interprets data imparted as a command for action is converted by a first conversion means corresponding to first data remained in a first retaining means to impart it to the external ROM. The data obtained from the external ROM is converted by a second conversion means corresponding to a second data retained by a second retaining means to impart it to the CPU. Therefore, the CPU executes the program in the ROM. Thus, a security of the program in the ROM externally installed can be easily ensured.</p> |
