APRIL 3--The Institute of Electrical and Electronics Engineers Standards Association (IEEE-SA; Piscataway, NJ; www.standards.ieee.org) Standards Board has approved IEEE Standard 1394b, "High-Performance Serial Bus," which amends the IEEE 1394-1995 and IEEE 1394a-2000 standards. IEEE 1394b upgrades the prior standards by allowing for gigabit signaling and by extending signaling distance to 100 meters (vs. 4.5 meters in IEEE 1394-1995) in data storage, home network backbones, and other systems.
The IEEE 1394-1995 standard was widely deployed, and many digital consumer and nonconsumer products based their primary external interface on it. IEEE 1394b expands the number and type of devices that can use this standard. The amendment also supports a broader range of interconnect media, from CAT5 unshielded twisted pairs and UTP5 to glass and plastic optical fiber. It allows for cable lengths of 50 meters for plastic-optical-fiber cables and 100 meters for glass optical fiber cables. It also supports SIN S100 (100 Mbit/s) operation over CAT-5 at lengths to 100 meters.
Under the new amendment, high-speed serial buses integrate with most IEEE standard 34- and 64-bit parallel buses, which enables low-cost interconnection among external peripherals. The new amendment is fully interoperable with 1394a-2000 and 1394-1995 for 6- and 4-pin connectors. It extends bus speeds to S800 and S1600 and has architectural support for S3200.
IEEE 1394b supports data/strobe signaling and the speeds inherent in IEEE 1394a-2000 and 1394-1995. It also adds beta-mode signaling for much higher data rates between beta-mode ports. For copper-cable connections shorter than 5 m, ports on the PHY developed for IEEE 1394b can signal by either data-strobe or beta mode. These ports select the optimum connection method. The new signaling system also provides for scalability as signaling rate increases and allows data transmission to overlap the transmission of arbitration signals in the reverse direction, which eliminates arbitration gaps in 1394b buses.
In addition, a bus with all connections operating in beta mode is completely self-timed and does not need a setting for gap count. The IEEE 1394b standard covers such elements as cables and connectors for gigabit signaling; detection and resolution of physical loops in bus topology; circuit design for transmitting 8b/10b encoded signals; extension of the PHY/link interface for higher data rates over either an 8-bit parallel or bit-serial bus; protocols to encode bus arbitration signals as symbols; protocols for signal speed negotiation between peer devices; and testing and compliance procedures for gigabit connections.
The amendment was sponsored by the Microprocessor and Microcomputer Standards Committee of the IEEE Computer Society. The IEEE-SA, an internationally recognized standards-setting body, develops consensus standards through an open process that brings diverse parts of an industry together. It has a portfolio of more than 870 completed standards and more than 400 in development. IEEE-SA promotes the engineering process by creating, developing, integrating, sharing and applying knowledge about electro- and information technologies and sciences for the benefit of humanity and the profession.
