PURPOSE: To facilitate the analysis of data by reading out the contents of a register even after the hardware is reset.

CONSTITUTION: A host information processor 1 identifies the occurrence a fault or no-answer state of a data processor 3 and sets the hardware in an initial state. Under such conditions, an interruption is requested to a microprocessor 5 via a hardware reset signal line 11. The microprocessor 5 saves the contents of the registers 41-4n and an internal-register 6 to a saving memory 3 through the firmware. That is, the firmware clears the memory 3 and saves the contents of the registers 41-4n and the register 6 to the memory if the firmware decides that the interruption request given from the processor 1 is equal to a hardware resetting instruction. When those saving operations are complete, the microprocessor 5 initializes the processor 2. Then the date are reed out of the memory 3 by the processor 1 after the hardware is reset.