The interface between a user and the system controller is via a monitor, such as a cathode ray tube (CRT) 65, and a light pen 66, as depicted in FIG. 1C.FIG. 1C is an illustration of a portion of an exemplary system user interface used in conjunction with the exemplary CVD processing chamber of FIG. 1A. System controller 60 includes a processor 61 coupled to a computer-readable memory 62.