JPH05289764

PURPOSE:To provide an information processing system with an automatic return function returning the state of the system at the time of reapplying power source to the state at the time of turning off power source and an information processing system without the function with interchangeability. CONSTITUTION:When an interruption signal (b) is outputted from a power source 2 at the time of turning off power source, a central processing unit 1 stops a processing, a system information monitoring mechanism control unit 4 saves the values of the internal register of the central processing unit 1 and the I/O register of an I/O unit in an external storage device 7. When an initialized signal (a) is outputted from the power source unit 2 at the time of reapplying power source, an automatic return processing mechanism control unit 3 makes the central processing unit 1 a hold state and starts the system information monitoring mechanism control unit 4. When the system information monitoring mechanism control unit 24 is started, it releases the hold of the central processing unit 1 after resetting the value of each register saved in the external storage device 7 to the original registers.