Monday, December 17, 2007

New FireWire S3200 Spec

Back in September, the 'USB Promoter Group' announced the next 'USB 3.0' specification. Many people were speculating that it might be the death blow for FireWire. Well, the FireWire folks aren't standing still. They just announced their next FireWire version called 'S3200', which builds on the earlier spec of IEEE1394b, also called FireWire 800. S3200 quadruples the speed from 800 Kbps to 3.2 Gbps and can use existing FireWire 800 cables and connectors.

We'll probably first see S3200 used with storage devices like external hard disks and optical drives. Eventually, they hope it will be adopted by consumer electronics manufacturers and used with home entertainment products. The new spec will let consumers connect HDTVs, set-top boxes and computers via coax cable with distances more than 100 meters.

Even though many motherboards are designed with a FireWire port, all include several USB 2.0 connections. With the huge success of USB and the expensive FireWire royalties, unless consumers see a big advantage like better audio and video performance, I think FireWire S3200 will have difficulty becoming as common as USB. Maybe people will understand that FireWire was specifically designed to be used for high speed streaming data and is ideal for a hard drive moving large chunks of data, like video. USB was originally designed for low bandwidth, low latency peripherals, like mice and keyboards. It allocates data bandwidth in inverse proportion to demand, so for example, mass storage gets whatever's left after mice, keyboards and tablets have had their share.

Here's a little more technical information on the topic. The USB 3.0 spec claims transfer speeds up to 10 times faster than USB 2.0, but the real world throughput of FireWire S3200 and its peer-to-peer technology might be better because of the overhead caused by USB's host/client technology. FireWire uses a double-simplex architecture, so for example, with the original FireWire speed of 400 Mbps, the actual aggregate speed is 800 Mbps. USB 1.0/2.0 uses a half-duplex architecture and 10% of its bandwidth is reserved for host commands. There are more delays inserted between TX and RX packets while the host and target devices' transceivers switch directions, wasting several microseconds each time. However, FireWire S3200 might become irrelevant because USB 3.0 is suppose to be 4.8 Gbps using double-simplex fibre, which is faster than S3200 on raw speed and finally gets rid of USB1/2's half-duplex overhead.

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