| 摘要 |
PURPOSE:To judge a reset factor of a processor without providing a hardware flip-flop by utilizing a fact that the contents of a volatile memory go to unstable in a state that a power source is disconnected. CONSTITUTION:A microprocessor 11 reads out the contents of the key word area of a RAM13. Also, it decides whether a read-out error is generated or not. In case of the read-out error, it is decided to be a reset caused by a power source turn-off a power source turn-on. In this case, the microprocessor 11 clears the whole area of the RAM13, and writes a prescribed key word in a key word area 16. On the other hand, in case the read-out error is not generated, whether a read-out data from the key word area 16 coincides with a prescribed value or not is decided. In case the decision is YES, it is decided that the reset is caused by other factor than turning off of the power source, and in case said decision is NO, it is judged that the reset is caused by a factor of turning off of the power source. |
