PURPOSE: To allow a free selection between a mode to restart with the system condition kept after releasing a stand-by mode and the mode to restart with the system condition initialized by selecting a register to set the condition of a system after releasing the stand-by mode with software.
CONSTITUTION: When a stand-by releasing signal is generated, a stand-by signal becomes an 'L' level, a system is started and an oscillating clock starts an action. When a register 3 is set to a mode in which the system is reset after releasing a stand-by mode then, a system reset signal is generated synchronizing with the stand-by releasing signal and the system involving a system clock is initialized. Then, the whole system except the oscillating clock is restarted at timing when the system reset signal becomes the 'L' level. Thus, the condition of the system after releasing the stand-by mode can be set arbitrarily with selection by software.