Abstract: 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.

Abstract: Magnetic signal level control apparatus for a printer or copier. A continuous sampling of the magnetic characteristics of a reference mark results in constantly adjusting to maintain the specified quality of magnetically readable characters on printed documents. A controller generates a signal which is applied to the developer of the printer to control application of magnetic ink or toner to the photoconductor and consequently to the paper. The invention also includes the method for controlling magnetic signal level.