| 摘要 |
PROBLEM TO BE SOLVED: To prevent the occurrence of malfunction due to the failure of download data or an operational program. SOLUTION: A microprocessor 1 having a download data input terminal 6 from an outside part, PROM-A(2) and PROM-B(3) for storing programs for operating the microprocessor 1, and a diagnosing circuit 10 are connected through an address/data bus 5 to each other. The diagnosing circuit 10 is provided with a function for operating the sum check of each PROM area, and for outputting the result, a function for monitoring the operating state of each PROM by a WDT function, and for outputting the result, and a PROM alarm outputting terminal 17 for outputting the alarm of the PROM. A chip select generating circuit 4 generates a PROM select signal 7 by combining sum check diagnostic signals 13-14 and error signals 15-16 under the WDT monitor of the PROM to be outputted by the diagnosing circuit 10 with outside switching signals 11-12. |
