Abstract: A data entry and writing device is equipped with an optical detector comprising light emitting elements and light receiving elements disposed around an opening formed in the device, a character/graphic analyzer for analyzing the locus of a pen which is moved within the opening using time-series coordinate data to thereby perform character/graphic recognition and a display unit for displaying data entered through the character recognition. The data entry and writing device is placed on a form and data are handwritten on the form with the pen through the opening. This permits automatic data entry into the device and data is also displayed on the display unit. The device also includes an erroneous preventing circuit which automatically indicates where errors exist between the data entered by the pen and data processed by the device and guides a user to correct the errors.

Abstract: A digital receive signal is sampled by an A/D converter, and the position of a point at which the receive signal crosses a reference level is obtained in response to sampling data by an exclusive OR gate. A phase interval between the present sampling point and the point at which the receive signal crosses the reference level is obtained by an arithmetic circuit, and the phase of the present sampling point is obtained in accordance with the position of the crossing point, the phase interval P between the present sampling point and the crossing point obtained by arithmetic circuit, the phase of a preceding sampling point obtained by an I-bit parallel delay circuit, and the phase of a sampling point which is two points preceding to the present sampling point and obtained by an I-bit j-stage parallel delay circuit.