| 摘要 |
In a computer device, a latch circuit latches a program read from a ROM. Even when a program C is mistakenly read from the ROM in place of a correct program B, a CPU outputs an access signal to the ROM again to read the program B at the same address from the ROM, and a match detection circuit compares the program B with the program C output from the latch circuit. Since these programs fail to match with each other, the CPU outputs the access signal again. If the ROM outputs the program B correctly this time, the program B matches with the program B output from the latch circuit when the match detection circuit compares these programs. The CPU then executes the program B as correctly read ROM data. Thus, even when a program in the ROM is mistakenly read, safe operation by a correctly read program is ensured.
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