The computer 800 shown in FIG. 12 comprises a CPU (Central Processing Unit) 810 that executes the program, an input device 820 such as a keyboard and a mouse, a ROM (Read-Only Memory) 830 that stores various kinds of data, a RAM (Random Access Memory) 840 that stores operation parameters, a reading device 850 that reads the program from the recording medium 900, an output device 860 such as a disp