PURPOSE: To improve operability by reflecting the operational environment of each application program with once set operational environment of a system.

CONSTITUTION: The operational environment of the system is set (S4) and preserved in a file (S5) by depressing function keys according to a menu screen. When a menu program is activated again, the contents preserved in the file are used and the environment setting file of the application program is reloaded (S6) so that each application program can be coincident with the independently set operational environment of the system by using the file.