FireWire-B is higher speed, longer distance, more functionality, and a better connectivity experience. But what is it really? Here, Glyph tells it like it is.

FireWire-B: An Amendment to the 1394 Standard

"FireWire-B" is the common name given to a data interface standard defined by the Institute of Electrical and Electronics Engineers as IEEE Std 1394b-2002. 1394b is an amendment to the existing IEEE standard 1394-1995. An earlier amendment, 1394a-2000, formed the basis for the FireWire that has been widely available on both Macintosh and PC computers, as well as many proprietary systems, for many years.

What Benefits Does FireWire-B Provide?

The 1394b-2002 standard retains all the major features of 1394-1995 and 1394a-2000, but adds some others that are great improvements:

• A new signalling protocol called "Beta", which permits operation at higher data rates and at greater distances than the older "DS" protocol used in 1394/1394a.
• Higher data rates of 800 Mbps (S800) and 1600 Mbps (S1600). It also includes "architectural support" for 3200 Mbps (S3200) for the future.
• Greater cable distances, using a variety of cabling types, including not only the familiar copper wire of 1394a, but also optical fibre and CAT-5 twisted pair.
• Improved copper cables and connectors (9-pin plugs and sockets) that perform better at the higher speeds and greater distances.
• Speed-ups in arbitration and signalling, higher efficiency, suspend/resume, etc.

So if you want to run at S800 speed, you have to use the Beta protocol, as defined in 1394b-2002. Okay, that's no problem...

But it's easy to get confused! Watch out for these points:

• "1394b" is not the same as "S800" (800 Mbps). A 1394b device with a top speed of S400 is perfectly legal. There is no requirement that a 1394b-compliant device has to run at higher speeds.
• "1394b" is not the same as "Beta". Most 1394b-compliant devices will support the Beta protocol, because it's the major feature of the amendment. However, the "DS" protocol is still supported in 1394b.
• "Beta" is not the same as "S800". The Beta protocol can be run at the "old" 400 Mbps speed, or even slower.

The Fine Print On FireWire 800

Oh well, nothing is free:

• The longer cable lengths (to 100 m) are only available with optical fibre and CAT-5 cable.
• CAT-5 is limited to S100 -- a quarter the speed of old FireWire, though still as fast as Ethernet-100.
• The S1600 data rate is not yet implemented, and S3200 is but a dream.

And this one's a little tricky:

• The Beta protocol and higher speeds are supposed to be supported ONLY on Beta cable with the new 9-pin connectors.

That is, the standard says: "A bilingual or Beta-only PHY port shall not be connected to either the 4- or 6-circuit sockets defined by IEEE Std 1394-1995 or IEEE Std 1394a-2000." (Par. 3.10.4.1)

But in practice you will find that some S800-capable devices, that also supply a 4-pin or 6-pin port for back-compatibility, will support Beta protocol on the old (legacy) ports. It's there, but strictly speaking you're not supposed to use it on those ports. (This will get explained in an expanded version of this page, hang tight...)

Okay, What is "FireWire-800"?

"FireWire-800" is a popular marketing name for a particular subset of 1394b-2002 characteristics, applied to a given device. Basically it implies "this device runs at S800". But there is no definition of "FireWire-800", since it has no official standing with regard to the IEEE, or 1394b-2002 or any other standard. It's just a popular (and admittedly catchy) name. In fact, Glyph uses it just like everybody else.

Great. So What Does "FireWire-800" Actually Mean?

1. Technically First.

Coming from Glyph, "FireWire-800" means the device:

• ... can run at S800 speed (800 Mbps data rate), as well as at slower speeds.
• ... supports the IEEE-1394b "Beta" protocol (since that's needed to run at 800 Mbps).
• ... has at least one Beta or Bilingual port socket (since those sockets are associated with the Beta protocol).

In addition, a "FireWire-800" device ALSO:

• ... is usually back-compatible with old FireWire, by supporting the "DS" protocol in addition to the Beta protocol on Bilingual ports (d-uh, that's what "Bilingual" means).
• ... may have one or more 6-pin or 4-pin legacy S400 sockets (these should only support the DS protocol).

2. Performance-wise Next.

All other things being equal, a FireWire-800 device will theoretically out-perform a legacy FireWire device (one that only supports DS protocol at up to S400 speed).

"But" #1:

The speed of your computer, other FireWire devices, and your application software will probably limit your system performance before FireWire's limits will. Adding FireWire-800 cannot speed up your CPU, your software, or your other devices.

"But" #2:

In the vast majority of audio applications, where multi-spindle RAID is not involved, you won't notice a difference between S400 and S800 speeds, because the hard drive mechanism itself will impose a limit first. Hard drives that can saturate a legacy FireWire bus are pretty rare.

You can rely on Glyph to give you the straight truth, technically and otherwise.

We are taking the time to lay it out and make it understandable, and we appreciate you reading through all this stuff.

We believe that the more you know about FireWire, the more you'll be inclined to seek Glyph for your FireWire solutions!

Useful Links

IEEE Standards Site
Zayante FireWire-B Presentation (download PDF)