In the present invention, data input/output equipment is connected in communication with a host machine which provides a plurality of service application programs by designating system parameters of one or more common programs. A mode setting feature designates at least a program setting mode and an execution mode. A program RAM stores at least one common program being loaded from the host machine. A parameter setting feature designates parameters included in the common program loaded in the program setting mode to define a plurality of application programs, each of which is available for a specified service. A parameter RAM memorizes the designated parameters. An entry data RAM memorizes entry data, and a service selecting feature designates one of the application programs in the execution mode.
