SB-113 - National Semiconductor

TL/F/11006

Laser Beam Printer (LBP) Controller Solution Card SB-113

National Semiconductor

System Brief SB- 113

June 1990

Laser Beam Printer (LBP)

Controller Solution Card

TL/F/11006–1

FIGURE 1. A Laser Printer Block Diagram

SYSTEM DESCRIPTION

A Laser Beam Printer (LBP) can be divided into three sec-

tions: 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 syn-

chronizing 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 bit-

map image that is sent to the printer optics and mechanics.

The PDL contains the instructions needed to create the im-

aged 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 control-

ler.

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 differ-

ent 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 inter-

face, 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 in-

creases 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 inter-

nal 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 memo-

ry for code, font and image storage. The code and font re-

quire 512 kBytes for a PCLTM style printer, and 1.5 MBytes

for a PostScript type printer.

Series 32000Éis 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 RRD-B30M105/Printed in U. S. A.

TL/F/11006–2

FIGURE 2. Block Diagram of a Laser Printer Controller

DESIGN CHALLENGES

Performance

Get the best performance for the price.

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.

Component Count

Reduce component count through efficient bus architecture,

integration, and code density.

Code Compactness

Series 32000ÉArchitecture 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.

Graphics Support

Graphics supported by dedicated on-chip hardware and

specialized instructions for printer operations.

KEY COMPONENTS

NS32CG16, NS32CG160, CPU Function

NS32FX16, NS32GX32 or NS32GX320, FPU Function

NS32081, NS32181 or NS32381

NS32CG821 DRAM Controller Designed to Interface with

Series 32000 Embedded Processor

NS16C451/NS16C551 UART with Parallel Interface,

(FIFOs, and Decode Logic)

EPROM Program and Font Storage

DRAM Working Space and Data Buffers

EEPROM 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

Memory

EPROM 1 Mbyte NMC27C010 8

DRAM 4 Mbyte

EEPROM 256 Byte NMC93CS56 1

Memory Control DRAM Controller NS32CG821 1

Logic

System ASIC Interface (Note 1) 1

Note 1: The system ASIC may be designed using National’s ASIC capabilities.

SB-113 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:

1. Life support devices or systems are devices or 2. A critical component is any component of a life

systems which, (a) are intended for surgical implant support device or system whose failure to perform can

into the body, or (b) support or sustain life, and whose be reasonably expected to cause the failure of the life

failure to perform, when properly used in accordance support device or system, or to affect its safety or

with instructions for use provided in the labeling, can effectiveness.

be reasonably expected to result in a significant injury

to the user.

National Semiconductor National Semiconductor National Semiconductor National Semiconductor

Corporation Europe Hong Kong Ltd. Japan Ltd.

1111 West Bardin Road Fax: (

49) 0-180-530 85 86 13th Floor, Straight Block, Tel: 81-043-299-2309

Arlington, TX 76017 Email: cnjwge

tevm2.nsc.com Ocean Centre, 5 Canton Rd. Fax: 81-043-299-2408

Tel: 1(800) 272-9959 Deutsch Tel: (

49) 0-180-530 85 85 Tsimshatsui, Kowloon

Fax: 1(800) 737-7018 English Tel: (

49) 0-180-532 78 32 Hong Kong

Fran3ais Tel: (

49) 0-180-532 93 58 Tel: (852) 2737-1600

Italiano Tel: (

49) 0-180-534 16 80 Fax: (852) 2736-9960

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.