Patent ID: 8341343

Claim:
A controller that controls a controlling subject, the controller comprising: a first memory part that stores memory contents while receiving electric power from a power supply; a second memory part that stores the memory contents even while not receiving the electric power from the power supply; a controlling part that controls the controlling subject by using data stored in the first memory part; a backup part that reads the data stored in the first memory part, and that writes the data as backup data in the second memory part; a first judging part that judges abnormality of the first memory part; a second judging part that judges abnormality of the second memory part based on (1) results of comparing with each other data having a same content written in the second memory part multiple times, and (2) a total amount of the data read out from the second memory part, when the first memory part is judged to be abnormal by the first judging part; a third judging part that judges abnormality of the second memory part based on results of comparing the data written in the second memory part with the data read out from the second memory part; a writing part that writes the backup data of the second memory part into the first memory part when the second memory part is not judged to be abnormal by the second judging part; and a prohibiting part that prohibits control of the controlling subject by the controlling part when the second memory part is judged to be abnormal by both the second judging part and the third judging part.