To make changeable the functions at need by making the control mechanism of a product usable for a general purpose by providing a means that positions a mechanism inside the product as the set of instructions to an external function to be controlled and exchanges the instructions.

This invention provides a device (hereinafter processor) for performing processing by referring to an electronic document (hereinafter program) in which processing to be performed according to fixed procedures described in a specific storage area is written with it as a turning point to receive a signal from the outside and for transmitting a signal according to a program instruction, an electronic part (hereinafter function to be controlled) for performing a prescribed operation while transmitting and receiving the signal to/from the processor and the program for linking the processor with the function to be controlled.