A panel positioned over the face of a cathode-ray tube with transmitters mounted along two adjacent edges of the panel to generate beams, either Rayleigh wave beams or light beams, that propagate through the panel to detectors mounted along opposite panel edges. The beams are directed to intersect in an X-Y matrix pattern. Interruption of intersecting beams by touching the panel at the intersection with a beam interrupting object, such as with a finger, develops discrete output signals at the two detectors that define the intersection. The output signals may be applied to a computer which may also be used to control the CRT to display various successive control panel patterns which have correspondence with the beam matrix intersections and are congruent with the intersections.