Abstract: Sensor apparatus for taking position signals from either ignited or extinguished cell positions at intersections of the column and row coordinate conductors of a gas tube display screen associated with an information handling system. The sensor apparatus includes a hand-held stylus having a plurality of spaced plates that capacitively interact with the adjacent row-column conductors as signal potentials are applied thereto by the normal gas panel addressing circuitry. The capacitive interaction of the plates causes signals to be picked up from the row-column conductors, the signals being differentially amplified to give a detect signal of the stylus position on the display which has a high degree of resolution, the detect signal in combination with data from the addressing circuitry giving a row-column (X-Y) coordinate address indication of the stylus on the panel for utilization in any associated information handling system.