System for adding desirable function to a computer from a portable electronic data communication device to control the portable device connected thereto

摘要

In a communication apparatus equipped with a control apparatus, an apparatus main body of this communication apparatus is connectable with an external unit. When this external unit is connected to the apparatus main body, an additional function may be realized in this communication apparatus. The external unit is comprised of a program storage means for previously storing thereinto a program used to control operation of a circuit built in the external unit. The apparatus main body does not store the program, but is comprised of a control means for controlling the operation of the circuit provided in the external unit in accordance with the program previously stored in the program storage means within the external unit.