National Semiconductor System Brief SB- 113 June 1990 TL/F/11006 - 1 FIGURE 1. A Laser Printer Block Diagram SYSTEM DESCRIPTION A Laser Beam Printer (LBP) can be divided into three sections: mechanics, optics, and electronics, as can be seen in Figure 1 . The mechanics of an LBP handle the physical path of the paper. The optics generate the laser beam and synchronizing signals. The electronics control the laser printer operation and are often referred to as the LBP formatter or RIP (Raster Image Processor). The LBP formatter performs computation and control tasks aimed at transferring images, provided by the host computer in a Page Description Language (PDL) format, to the bitmap image that is sent to the printer optics and mechanics. The PDL contains the instructions needed to create the imaged page, a task that requires a high performance 32-bit CPU. In addition the formatter controls the operation of the user panel and the printing engine. Inputs are received from microswitches, sensors, and the video controller. Outputs are fed to motors, solenoids, relays, and the video controller. Embedded processors are specifically targeted to execute in the imaging environment. A family of processors to cover low-to-high range LBP applications is available, with different degrees of performance and integration. The choice of an embedded processor for a non-impact printer controller is of high importance. The processor should be selected by considering its impact on the system cost and performance. The applicability of the instruction set, integration, bus interface, and development tools are important issues. Figure 2 shows a block diagram of an LBP controller. The choice of CPU, for high-performance printer formatters, or for mid-range performance should have the same level of integration, including on-chip Interrupt Control Unit (ICU), 2-channel DMA Controller (DMAC), and 3 timers/counters. The hardware Floating Point Unit (FPU) is optional. It increases the system performance, typically by 20%, when running PostScriptTM . For small memory systems a 16-bit data bus is provided, which is fully transparent to the internal 32-bit architecture. A 32-bit external data bus, with burst mode, is used for high-performance systems. The control logic, the 32-bit video shifter, the printer mechanism control, and the keyboard display control, may all be implemented in a system ASIC. To support RS-232 serial interface, and a Centronics type interface. UART with parallel interface, or a UART with FIFOs, parallel interface, and decode logic, may be used. PDLs are large programs requiring large amounts of memory for code, font and image storage. The code and font require 512 kBytes for a PCLTM style printer, and 1.5 MBytes for a PostScript type printer. SB-113 Series 32000E is a registered trademark of National Semiconductor Corporation. PCLTM is a trademark of Hewlett Packard Corporation. PostScriptTM is a trademark of Adobe Systems, Incorporated. C1995 National Semiconductor Corporation TL/F/11006 Laser Beam Printer (LBP) Controller Solution Card Laser Beam Printer (LBP) Controller Solution Card RRD-B30M105/Printed in U. S. A. TL/F/11006 - 2 FIGURE 2. Block Diagram of a Laser Printer Controller 2 DESIGN CHALLENGES Code Compactness Performance Get the best performance for the price. Series 32000E Architecture code is the most compact in the industry, and may be some 60% less is size then a generic RISC code, which relates to fewer EPROMs in the system for lower cost and smaller size. For a solid performance of 4 to 15 pages per minute (ppm) printer the NS32CG16, NS32CG160, and NS32FX16, are recommended. For printers of 15 ppm and beyond the NS32GX32 and NS32GX320 are the processors of choice. Graphics Support Graphics supported by dedicated on-chip hardware and specialized instructions for printer operations. Component Count Reduce component count through efficient bus architecture, integration, and code density. KEY COMPONENTS NS32CG16, NS32CG160, NS32FX16, NS32GX32 or NS32GX320, NS32081, NS32181 or NS32381 NS32CG821 NS16C451/NS16C551 EPROM DRAM EEPROM CPU Function FPU Function DRAM Controller Designed to Interface with Series 32000 Embedded Processor UART with Parallel Interface, (FIFOs, and Decode Logic) Program and Font Storage Working Space and Data Buffers Setup Storage BILL OF MATERIAL OF MAJOR COMPONENTS 15 PPM LBP CONTROLLER Function Description NSC Part Other Mfg Qty CPU Embedded Processor NS32GX320 1 FPU Floating-Point Unit NS32381 1 Interface Serial and Parallel Interface NS16C451 1 EPROM 1 Mbyte NMC27C010 8 DRAM 4 Mbyte EEPROM Memory Control 256 Byte DRAM Controller NMC93CS56 NS32CG821 1 1 Interface (Note 1) 1 Memory Logic System ASIC Note 1: The system ASIC may be designed using National's ASIC capabilities. 3 Laser Beam Printer (LBP) Controller Solution Card LIFE SUPPORT POLICY NATIONAL'S PRODUCTS ARE NOT AUTHORIZED FOR USE AS CRITICAL COMPONENTS IN LIFE SUPPORT DEVICES OR SYSTEMS WITHOUT THE EXPRESS WRITTEN APPROVAL OF THE PRESIDENT OF NATIONAL SEMICONDUCTOR CORPORATION. As used herein: SB-113 1. Life support devices or systems are devices or systems which, (a) are intended for surgical implant into the body, or (b) support or sustain life, and whose failure to perform, when properly used in accordance with instructions for use provided in the labeling, can be reasonably expected to result in a significant injury to the user. National Semiconductor Corporation 1111 West Bardin Road Arlington, TX 76017 Tel: 1(800) 272-9959 Fax: 1(800) 737-7018 2. A critical component is any component of a life support device or system whose failure to perform can be reasonably expected to cause the failure of the life support device or system, or to affect its safety or effectiveness. National Semiconductor Europe Fax: (a49) 0-180-530 85 86 Email: cnjwge @ tevm2.nsc.com Deutsch Tel: (a49) 0-180-530 85 85 English Tel: (a49) 0-180-532 78 32 Fran3ais Tel: (a49) 0-180-532 93 58 Italiano Tel: (a49) 0-180-534 16 80 National Semiconductor Hong Kong Ltd. 13th Floor, Straight Block, Ocean Centre, 5 Canton Rd. Tsimshatsui, Kowloon Hong Kong Tel: (852) 2737-1600 Fax: (852) 2736-9960 National Semiconductor Japan Ltd. Tel: 81-043-299-2309 Fax: 81-043-299-2408 National does not assume any responsibility for use of any circuitry described, no circuit patent licenses are implied and National reserves the right at any time without notice to change said circuitry and specifications.