Abstract: A power supply unit is arranged between a CPU and a power supply device for supplying power to the CPU. Information necessary in proceeding with a program is evacuated from the CPU to an information holding unit. When a power shutdown factor is generated, a power supply control unit outputs a shutdown request signal to the CPU. The CPU, upon receiving the shutdown request signal, activates a power shutdown microprogram, evacuates the information necessary in proceeding with the program to the information holding unit, and outputs an evacuation completed signal to the power supply control unit after the evacuation is completed. Upon receiving the evacuation completed signal, the power supply control unit outputs a power shutdown control signal to the power supply unit. Upon receiving the power shutdown control signal from the power supply control unit, the power supply unit shuts down power supply to the CPU.

Abstract: A microcomputer debugging system capable of executing a plurality of debug modes, wherein processing is not allowed to shift to an interruption program during a debugging operation in one of the plurality of debug modes, and is allowed to shift to the interruption program during the debugging operation in another debug mode.

Abstract: A power supply unit is arranged between a CPU and a power supply device for supplying power to the CPU. Information necessary in proceeding with a program is evacuated from the CPU to an information holding unit. When a power shutdown factor is generated, a power supply control unit outputs a shutdown request signal to the CPU. The CPU, upon receiving the shutdown request signal, activates a power shutdown microprogram, evacuates the information necessary in proceeding with the program to the information holding unit, and outputs an evacuation completed signal to the power supply control unit after the evacuation is completed. Upon receiving the evacuation completed signal, the power supply control unit outputs a power shutdown control signal to the power supply unit. Upon receiving the power shutdown control signal from the power supply control unit, the power supply unit shuts down power supply to the CPU.

Abstract: In a microprocessor that interprets instructions where a same instruction code can be interpreted as separate instructions with respectively different data lengths, a data length storage circuit that stores data length selection-use information is provided in a decoding unit. Instructions instructing storage to a general-purpose register, such storage of 8-bit immediate data to register R1, are set in advance as first-type instructions. Instructions that do not explicitly specify a data length, in other words, instructions whose processing targets are various lengths of data stored in the general-purpose register are set in advance as second-type instructions. When decoding a first-type instruction, the decoding unit updates the data length selection-use information in accordance with the first-type instruction.