PURPOSE: To make a quick correction by finding an abnormality due to the dynamic operation of the stand-by CPU and to normally start operation as soon as it is switched to the stand-by CPU by allowing a CPU in operation to periodically start the stand-by CPU and to perform self-diagnosis and storing the diagnosis result in a state register monitored by the operating CPU.
CONSTITUTION: A CPU 1 turns on a pulse generator 3 periodically and sends a pulse to a self diagnosis start monostable multivibrator 6-1 to start. It sends a 1-level signal to a CPU 2 through OR circuits 19 and 23, releasing the stand-by state of the CPU 2 and sending the 1-level signal to a self diagnosis display register 8 to make it self-diagnosing. When the register is in the self diagnosis, the CPU 2 reads out a self diagnosis program 21 from a ROM 25, and performs the self diagnosis of the dynamic operation in the operation of the self-diagnosis start monostable multivibrator 6-1, storing the result in a state register 7. The CPU 1 notifies an abnormality to a monitoring device 31 to display the abnormality of the CPU 2.
MARUYAMA TAKUMI
NAKAJIMA RYOETSU
YOSHIDA MITSUNOBU
YAMAZAKI NAOKI
Next Patent: FAULT PROCESSING DEVICE FOR INFORMATION PROCESSOR