PURPOSE: To specify the cause of generating the fault of a processor without fail by storing a data required for analyzing the fault, holding the data and analyzing the cause of generating the fault at another device.

CONSTITUTION: While operating a processor 10, a data showing the operational state is written in a storing means 12 of a substrate 20 and when the fault is generated, the substrate 20 is detached from the processor 10. The data stored in the storing means 12 of the detached substrate 20 is held by a holding means 14 and further, the read request of the stored data to be applied from the outside is accepted by an accepting means 16. According to the accepted read request, the stored data is read from the storing means 12 by an output means 18 and outputted to the outside. Thus, the operational state when generating the fault is read out at the other device by using the detached substrate 20 so as to specify the cause.