PURPOSE: To facilitate the correction, change, erasion, etc., of data by displaying the desired data to be corrected on a CRT screen, dividing the CRT screen into plural parts, and displaying only these divided parts on a liquid crystal display LCD which is set under a digitizer.
CONSTITUTION: When an operator touches the part of 'LCD ON' in a function area 7 of a digitizer 1 by means of a signal detection pen 2, the corresponding data are displayed on an LCD 5 secured at the lower left corner of a CRT. Then the tip of the pen 2 has a touch to the stage part of a recess part 11 of the digitizer 1 for selection of a part of the CRT screen where the correction, erasion, etc., are desired. Then the pen 2 detects a signal out of an electrode. When the addition of a line is desired to the screen, an input area is touched by the pen 2 and then a new line is drawn at the part of a coordinate input area of the LCD 5. When the partial erasion of the screen is desired, an erasion item is touched with the pen 2 and then the desired line to be erased out of the LCD 5 is copied by the pen 2. Thus the relevant data can be erased.