A data processing system includes a multipurpose data input device formed by a touch screen and a digitizing tablet integrated with one another, which are activatable independently of each other by proper stimuli. The touch screen and the digitizing tablet each comprise a respective sensing means to sense the proper stimuli. The respective sensing means comprise respective components for producing respective signals representative of the proper stimuli, the respective components being physically and functionally distinct from one another. The input device is integrated with a flat panel display in order to establish a visual feedback to the user or to present information pertaining to the entered data after processing. The flat panel display, touch screen and digitizing tablet take a variety of forms and a variety of techniques are utilized to determine which of the touch screen and digitizing tablet is activated at any time.