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Reduced Media Interface for Ethernet PHYs Enables Lower-Cost, Higher-Density Networking Devices

AMD, Broadcom, National Semiconductor and Texas Instruments Define New Specification

Sep 30, 1997

DALLAS (Sept. 30, 1997) -- Advanced Micro Devices (AMD) (NYSE: AMD), Broadcom Corporation, National Semiconductor Corporation (NYSE: NSM) and Texas Instruments (TI) (NYSE: TXN), today announced a jointly developed specification for a Reduced Media Independent Interface (RMII) intended for use between 10/100Mbps Ethernet physical layer interface (PHY) devices and switch silicon. By reducing the pin count and the complexity of the interface between the media access controller (MAC) and PHY components, the RMII will make it easier and less costly for system providers to build network switching solutions.

Overview of the RMII Specification
The Ethernet standard (IEEE 802.3µ) defines a MII with 16 pins per port for data and control. In devices incorporating many MAC or PHY interfaces, such as switches or port-switched repeaters, the number of pins can add significant costs as port counts increase. For example, in a typical 24-port switch configuration, the RMII could reduce the number of MAC pins from 16 to six per port, for a total savings of 239* pins.

The RMII reduces PHY costs while maintaining features currently available in PHY layer silicon:

  • All the functionality of 802.3µ MII.
  • Operation at either 10 Mbps or 100 Mbps data rates, supporting the migration towards high-speed Ethernet products.
  • Implementation of a single synchronous clock reference that is sourced from the MAC to PHY (or from an external source), to simplify the clocking interface.
  • Support for existing features such as full-duplex capability in switches.
The RMII is optimized for use in high-port-density interconnect devices, primarily network switch ASICs, that require independent treatment of the data paths between the MAC and PHY. The RMII is also useful for port-switched repeater ASICs that integrate more than one repeater core and provide a mapping function between PHY interfaces and internal segments.

Joint Development and Publication
The RMII specification was developed as a cooperative effort by AMD, Broadcom, National, and TI in order to meet customer demands for new PHY solutions that are available from multiple vendors. The specification was developed in cooperation with leading network equipment providers.

The published RMII specification document is available now at AMD's websitehttp://www.amd.com, Broadcom's website http://www.broadcom.com, National's website http://www.national.com/appinfo/lan, and TI's website http://www.ti.com/sc/docs/network/nbuhomex.htm.

*One pin has been reserved for clock function.

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About AMD

AMD is a global supplier of integrated circuits for the personal and networked computer and communications markets. AMD produces processors, flash memories, programmable logic devices, and products for communications and networking applications. Founded in 1969 and based in Sunnyvale, California, AMD had revenues of $2 billion in 1996. (NYSE:AMD). Press announcements and other information about AMD are available on the Internet via the World Wide Web. Type http://www.amd.com at the URL prompt.



About Broadcom

Since its founding in 1991, Broadcom Corporation has become a worldwide leader in the data communications market, providing integrated, system-level silicon solutions to manufacturers of 100BASE-T, cable modem, digital cable-TV set-top box, xDSL and digital broadcast satellite equipment. The company's QAMLink digital transmission technology is used by leading manufacturers of hubs, switches, routers and line cards. The company has strategic customer relationships with the leading data communications equipment manufacturers, including: 3Com, Bay Networks, Inc., Cisco Systems, Intel, NextLevel Systems (formerly General Instrument Corp.), Motorola and Scientific Atlanta. Broadcom is based in Irvine, CA, and can be reached at (714) 450-8700 or at http://www.broadcom.com.



About National Semiconductor

National Semiconductor Corporation, a Fortune 500 company, produces system-on-a-chip silicon solutions for the information highway, based on its leadership in analog and mixed signal technologies. National is headquartered in Santa Clara, California, and focuses on the communications, personal systems, and consumer markets. National has annual sales of approximately $2.5 billion and 12,700 employees worldwide. Additional company and product information is available on the World Wide Web at http://www.national.com.



About Texas Instruments

An industry pioneer and the worldwide leader in digital signal processing solutions, Texas Instruments celebrates the 15th anniversary of its first DSP in 1997. TI provides innovative DSP solutions to more than 20,000 customers worldwide in the computer, communications, consumer, automotive, military and industrial markets. TI was recognized by IEEE for technical excellence in the design and application of DSPs by receiving the 1996 IEEE Corporate Innovation Recognition Award. TI offers a unique breadth of digital and mixed-signal products and technologies, hardware and software development tools, design information services and global support.



Texas Instruments Incorporated is a global semiconductor company and the world’s leading designer and supplier of digital signal processing solutions, the engines driving the digitization of electronics. Headquartered in Dallas, Texas, the company’s businesses also include calculators, productivity products, controls and sensors, metallurgical materials and digital light processing technologies. The company has manufacturing or sales operations in more than 25 countries.



Texas Instruments is traded on the New York Stock Exchange under the symbol TXN. More information is located on the World Wide Web at http://www.ti.com.