PURPOSE: To accelerate processing speed in the case of executing the system by switching an environment when debugging the system and executing the system.

CONSTITUTION: This system is equipped with a mode switching part 101 to switch a debugging mode to be designated when requiring debugging and an execution mode to be designated when debugging is not required, error check presence function load part 102 to load the group of functions containing error checks onto a memory, error check absence function load part 103 to load the group of functions containing no error check onto the memory, and execution part 104 to analyze and execute inputted instructions one by one.