1. A method for calibration of touchscreen display coordinates by an operator comprising: (a) displaying at least one calibration target, the calibration target corresponding to a calibration reference point; (b) sensing a calibration touch for the at least one calibration target; (c) obtaining a calibration touchpoint coordinate for the calibration touch; (d) determining if the calibration touchpoint coordinate is valid; and (e) if so, storing the calibration touchpoint coordinate in a touchpoint history database and using the calibration touchpoint coordinate to define a calibration reference point for operation, otherwise generating a computed reference calibration point using a predetermined number of calibration touchpoint coordinates in the touchpoint history database.