A control system coupled with a laser printer to enhance and expand the capabilities of the printer. A microprocessor with memory components having different functions is coupled between a host computer and the raster image processor of the printer through appropriate interfaces. Bidirectional communication is afforded between the hose and the microprocessor, as well as between the printer and the microprocessor. The system has an audit trail feature which enables the printer to provide security when generating financial forms and negotiable instruments such as checks. The system also has means to facilitate external updating of its control code without changing any hardware on the board.