| 摘要 |
PURPOSE:To monitor address malfunction and to attain a normal return by dividing a program into modules and providing a characteristic index and an index confirming instruction, storing the characteristic index by instruction execution, and detecting the instruction execution and comparing a generated index. CONSTITUTION:The program is executed successively, an index 1 is written in an index register 11 by the index write instruction of the 1st module, and an output significance signal 15 is sent to an incrementer 14 to add one to the contents of the index counter 12. As modules are executed successively, the register 11 and counter 12 are increased equally, one by one, and their contents are compared with each other by an index comparator 13, but they are equal in contents, so a dissidence signal 16 is not sent out. If a jump to a wrong module is caused owing to malfunction, the index is different, so the comparator 13 outputs the signal 16, allowing a CPU17 to perform error processing. An index counter initializing instruction is executed at a head part at the time of branching, returning, or repetition to write the value obtained by subtracting one from the index in the counter 12, and the index is increased by one in the ending, so the indexes become equal. When the signal 16 is received by the CPU17, the contents of the counter 12 are read out and a return to a normal loop is attained. |
