Blane
1
IEEE 1394b is ready to roll, loaded with bandwidth, speed, distance and other improvements, along with total compatibility with the original IEEE 1394-1995 and 1394a versions.
IEEE 1394b will supplement the legacy IEEE 1394-1995 and 1394a specifications. It keeps all the vital features of those earlier versions: point-to-point connectivity, peer-to-peer operation, plug-and-play capability, isochronous operation (guaranteed timing) and asynchronous operation (guaranteed delivery, complete reliability) and, of course, a very logical bus model.
But IEEE 1394b will lead to expanded adoption in many of the applications where 1394 is firmly established, including DTV, set-top boxes, VCRs and DVDs. Virtually all of these products will be 1394-enabled by the year 2002. The 'b' version also paves the way for a new round of application development for home networking, with its high speeds, low bit error and guaranteed latency requirements. IEEE 1394b's enhancements also definitely will benefit computer peripherals, which require higher speeds as disk-head read rates increase and as the pixel densities and color depths in imaging devices such as printers and scanners continue to improve.
IEEE 1394b allows extensions to 800Mbit/sec., 1.6Gbit/sec. and 3.2Gbit/sec., all over copper wire. It supports long-distance transfers to 100 meters over a variety of media: CAT-5 unshielded cable at 100Mbit/sec., existing plastic optical fiber at 200Mbits/sec., next-generation plastic optical fiber at 400Mbit/sec. and 50-micron mulitmode glass optical fiber at up to 3.2Gbit/sec. The improved speed and distance capabilities of 1394b result from two major improvements: overlapped arbitration and advanced data encoding.
The highly efficient bus arbitration scheme, known as BOSS (Bus Owner Supervisor Selector), implements overlapped, pipelined arbitration, so the arbitration protocol runs in parallel with data transmissions. This is different from the 1394-1995 and 1394a legacy versions, both of which alternate between data transmission and arbitration.
The data encoding improvements are based on the 8B10B codes used by Fibre Channel and Gigabit Ethernet and add more robust control codes and scrambling of both data and control symbols. This scrambling results in much lower average emissions—more than 20dB below unscrambled codes. Together, the two improvements are called the beta mode of operation to distinguish it from the 1394-1995/1394a legacy mode.
The costs of 1394b silicon and 1394b-enabled products are expected to be roughly the same as products using earlier versions, while silicon and products that use only the beta mode will be even less. Gate counts for 1394b ICs will double to between 20,000 and 25,000, but the beta-only version, using unidirectional arbitration signaling instead of common-mode signaling, will reduce voltages and allow galvanic isolation for much simpler analog design and reduced die size. Another key application permitted by 1394b is casual storage, the kind that hard drive and mobile storage users hook up at random times. The 1394b standard provides significant amounts of bus power (up to 25 watts) along with aggressive power management so that power is only used when actually needed; users with portable computers and peripherals that want to use casual storage will not need a battery-powered drive or power bricks. Both hard disks and optical media such as CDs, DVDs and CD-RW require more than 5W while seeking and spinning up, making this an important issue. Products and technology based on 1394b are already here or on the way. Look for silicon from Texas Instruments, NEC, Panasonic and Agere sometime in the third and fourth calendar quarters. Using previous versions of the 1394b specification, Omneon Video Networks is shipping digital video distribution networks with 300m, 800Mbit/sec. connections using multimode glass fiber, and NEC Corp. is shipping a plastic optical fiber system. New connectors, with much improved shielding and signal isolation, from Molex Inc. are ready now.
IEEE 1394b will supplement the legacy IEEE 1394-1995 and 1394a specifications. It keeps all the vital features of those earlier versions: point-to-point connectivity, peer-to-peer operation, plug-and-play capability, isochronous operation (guaranteed timing) and asynchronous operation (guaranteed delivery, complete reliability) and, of course, a very logical bus model.
But IEEE 1394b will lead to expanded adoption in many of the applications where 1394 is firmly established, including DTV, set-top boxes, VCRs and DVDs. Virtually all of these products will be 1394-enabled by the year 2002. The 'b' version also paves the way for a new round of application development for home networking, with its high speeds, low bit error and guaranteed latency requirements. IEEE 1394b's enhancements also definitely will benefit computer peripherals, which require higher speeds as disk-head read rates increase and as the pixel densities and color depths in imaging devices such as printers and scanners continue to improve.
IEEE 1394b allows extensions to 800Mbit/sec., 1.6Gbit/sec. and 3.2Gbit/sec., all over copper wire. It supports long-distance transfers to 100 meters over a variety of media: CAT-5 unshielded cable at 100Mbit/sec., existing plastic optical fiber at 200Mbits/sec., next-generation plastic optical fiber at 400Mbit/sec. and 50-micron mulitmode glass optical fiber at up to 3.2Gbit/sec. The improved speed and distance capabilities of 1394b result from two major improvements: overlapped arbitration and advanced data encoding.
The highly efficient bus arbitration scheme, known as BOSS (Bus Owner Supervisor Selector), implements overlapped, pipelined arbitration, so the arbitration protocol runs in parallel with data transmissions. This is different from the 1394-1995 and 1394a legacy versions, both of which alternate between data transmission and arbitration.
The data encoding improvements are based on the 8B10B codes used by Fibre Channel and Gigabit Ethernet and add more robust control codes and scrambling of both data and control symbols. This scrambling results in much lower average emissions—more than 20dB below unscrambled codes. Together, the two improvements are called the beta mode of operation to distinguish it from the 1394-1995/1394a legacy mode.
The costs of 1394b silicon and 1394b-enabled products are expected to be roughly the same as products using earlier versions, while silicon and products that use only the beta mode will be even less. Gate counts for 1394b ICs will double to between 20,000 and 25,000, but the beta-only version, using unidirectional arbitration signaling instead of common-mode signaling, will reduce voltages and allow galvanic isolation for much simpler analog design and reduced die size. Another key application permitted by 1394b is casual storage, the kind that hard drive and mobile storage users hook up at random times. The 1394b standard provides significant amounts of bus power (up to 25 watts) along with aggressive power management so that power is only used when actually needed; users with portable computers and peripherals that want to use casual storage will not need a battery-powered drive or power bricks. Both hard disks and optical media such as CDs, DVDs and CD-RW require more than 5W while seeking and spinning up, making this an important issue. Products and technology based on 1394b are already here or on the way. Look for silicon from Texas Instruments, NEC, Panasonic and Agere sometime in the third and fourth calendar quarters. Using previous versions of the 1394b specification, Omneon Video Networks is shipping digital video distribution networks with 300m, 800Mbit/sec. connections using multimode glass fiber, and NEC Corp. is shipping a plastic optical fiber system. New connectors, with much improved shielding and signal isolation, from Molex Inc. are ready now.
