| 摘要 |
A microprocessor having two different modes of operation includes a mode flag which designates one of the two operation modes of the microprocessor, and a central processing unit which executes a program in one of the two operation modes designated by the mode flag. The central processing unit includes a microprogram memory which stores an interrupt initiation microprogram, an output device which is responsive to an interrupt request for reading out the interrupt initiation microprogram from the microprogram memory and a circuit for executing the interrupt initiation microprogram to generate a sampling signal. A mode terminal is provided, which is supplied with operation mode information. A circuit responsive to the sampling signal samples a logic level of the operation mode information at the mode terminal. A circuit is provided, which is responsive to the sampled logic level from the sampling circuit in order to bring the mode flag into one of set and reset states of the mode flag designation.
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