Electrographic apparatus

The electrographic apparatus of a variety wherein a transparent resistive layer is deposited upon an insultive substrate in a manner wherein a rectangularly-shaped resistive layer region is developed having a predetermined conductivity. A conduction band is provided about the periphery of the resistive layer region having a value of conductivity enhanced with respect to the conductivity value of the resistive layer. Discrete resistive elements are positioned intermediate the conduction band and the resistive region and four terminals are provided, one at each of the four corners of the rectangular resistance region. The discrete resistance elements are designed so that a uniform impedance is witnessed with respect to the resistive layer region as witnessed with respect to each of the four terminals. The control system for the device provides for development of coordinate pair information and includes a non-volatile memory retained configurational data for initial set-up of the apparatus by the opertor.