Abstract: The present invention is carried out to provide a system controller, a control system and a system control method which are inexpensive, highly stable, capable of storing all information and past record at a time when one of the devices is down and capable of switching the devices without any time lag. The system controller comprises a bus arbiter and a non-volatile memory and has only periodically executed functions and passive functions. The system includes a bus employing a center arbitration method, from which devices can be detached from and to which the detached devices can be attached again as power being supplied. Even if one of the devices is down, processes can be immediately continued by switching from the down device to other device by utilizing the system controller and the bus.

Abstract: The present invention is carried out to provide a system controller, a control system and a system control method which are inexpensive, highly stable, capable of storing all information and past record at a time when one of the devices is down and capable of switching the devices without any time lag. The system controller comprises a bus arbiter and a non-volatile memory and has only periodically executed functions and passive functions. The system includes a bus employing a center arbitration method, from which devices can be detached from and to which the detached devices can be attached again as power being supplied. Even if one of the devices is down, processes can be immediately continued by switching from the down device to other device by utilizing the system controller and the bus.