DATA PROCESSING UNIT

PURPOSE:To attain restoration of a route of a normal program automatically by providing a circuit detecting that a central processing unit does not execute the program of normal route and allowing its detected output to reset the central processing unit. CONSTITUTION:A fault detection circuit 20 and a data selection circuit 40 are provided in addition to the arithmetic processing by the central processing unit (CPU)1. The CPU1 repeates the data processing and outputs a supervisory pulse MP once per one cycle during that time. A start switch 41 is thrown normally to the position (b), the program is progressed, the reset of a counter 24 is released and the clock is counted. When the processing is given to other route than the normal route, no supervisory pulse MP is applied to a counter 24, and the counter 24 goes to high. Then a transistor 26 is turned on, the level of a reset terminal of the CPU1 goes to low level, the CPU1 is reset and the program is restarted.