PURPOSE: To improve the efficiency of work performance in a terminal device, by allowing a control circuit to divide and use a display unit and a memory.

CONSTITUTION: The signal from a communication line connecting circuit 1 is stored in a memory 4 and is controlled by a display control unit 2 and is displayed on a display unit 5. Input data from a keyboard is connected to the unit 2 and the circuit 1 through a keyboard control unit 3. The unit 2 is so constituted that the display area of the display unit 5 is divided to display data. When the display area of the unit 5 is divided, the operator designates the unit 2 and the dividing method of the memory 4 by a keyboard 6 and designates a work for which each divided area is used. The unit 2 stores data indicating that data inputted from the unit 3 hereafter is used for the designated work, and data inputted from the keyboard hereafter is outputted to designated areas of the memory 4 and the unit 5 by the unit 2.