PURPOSE: To transmit new module data up to the limit of a memory capacity by shifting a free area into an address range subsequent to the module area which is previously changed.

CONSTITUTION: The 1st-4th types of module data, for example, are stored in a storage device 4 in the corresponding module areas and at and after the initiation of an address. An area subrequent to the 4th module data through the termination is defined as an unused free area. When the 2nd module data are changed into the module data of the same type of an external equipment through an I/O port 13, a CPU 1 shifts the 3rd and 4th module data up to the termination of the address. Then, the module data are successively changed at an after the head of a 2nd module area based on the module data sent through the port 13. When the transmission of the module data is completed, the CPU 1 shifts the 3rd and 4th module data to a new area following the 2nd module data. The area subsequent to the 4th module through the termination is defined again as a free area.