A Look at Firewire 80 How FireWire 800/IEEE-1394b supports faster speeds, advanced cabling, and still works with your existing devices
A Look at Firewire 80
How FireWire 800/IEEE-1394b supports faster speeds, advanced cabling, and still
works with your existing devices
FireWire: The Next Generation
The technical name for the FireWire high-speed I/O port, IEEE-1394a, has always suggested that other versions of this standard would hit the market someday. In January 2003, the second generation of FireWire, FireWire 800 or IEEE-1394b, hit the market. In this article, you will learn how FireWire 800 differs from the original FireWire standard, now known as FireWire 400, and how you can continue to use your existing peripherals with this new port standard.
New Features of FireWire 800
FireWire 800 uses one of two new nine-pin cables and connectors to support speeds from 800Mbps up to 3200Mbps with copper or fiber-optic cabling. Initially 800Mbps is the top speed supported. In addition to faster speeds, FireWire 800 also has the following new features:
- Self-healing loops - If you improperly connect 1394b devices together to create a logical loop, the interface corrects the problem instead of failing as with 1394a.
- Continuous dual simplex - Of the two wire pairs used, each pair transmits data to the other device, so that speed remains constant.
- Additional cable standards supported - Support for fiber-optic and CAT5 network cable as well as standard 1394a and 1394b copper cable.
- Improved signal arbitration Supports faster performance and longer cable distances.
Note that although FireWire 800 can use the same CAT5 network cable used by 10/100 Ethernet and Fast Ethernet, it uses only wire pairs 1 & 2 and 7 & 8 for greater reliability. No crossover cables are required.
Beta and Bilingual Ports
FireWire 800 ports come in two varieties: Bilingual ports and Beta ports. Bilingual ports can connect to other FireWire 800 devices or to existing FireWire 400/IEEE-1394a/i.Link devices by using special adapter cables which have a nine-pin connector on one end and a six-pin or four-pin connector on the other end. Beta ports can connect only to other FireWire 800 devices.
Figure 1 shows that the pinouts for both port types are the same, but beta connectors and cables have a keyed differently than bilingual cables and connectors. This prevents attaching a bilingual adapter cable to a beta port.
| Figure 1 |
| Beta and bilingual ports and device compatibility |
Benefits of FireWire 800
Although the original version of FireWire/IEEE-1394 was designed to support networking as well as a wide variety of devices, the short cable lengths and limited cabling types supported limited its typical uses to DV camcorder interfacing, high-speed scanners and external hard drives. Since FireWire 800 supports additional cable types for longer signaling distance, has self-healing features, and allows direct device-to-device connections without a PC, it could be used as the basis for home networking of various multimedia devices.
FireWire 800 in the Marketplace
As might be expected from the history of the first FireWire standard, Apple has led the way in adopting FireWire 800, which is built into several of their new products, including the Xserve server and 17-inch version of the PowerBook G4. However, PC users can also use FireWire 800 drives and other devices as they become available, thanks to PCI host adapters from Indigita, Unibrain, and others. LaCies FireWire 800 drives also feature USB 2.0 ports, so you can use your choice of interfaces. This dual-interface feature is likely to be common on other vendors drives, since many vendors are using FireWire 800/USB 2.0 dual-interface chipsets such as the OXUF922 developed by Oxford Semiconductor.
Before you decide if FireWire 800 is right for you, be sure to consider the additional costs over USB 2.0. Although FireWire 800 is faster, you will need a host adapter card in most cases, while USB 2.0 is standard in most new systems.
Conclusion
FireWire 800 is in its infancy, and its too early to anticipate how popular it will be in the long run. However, since FireWire 800 features backwards-compatibility with the existing 400Mbps base of FireWire 400 devices, its likely to slowly replace FireWire 400 over the next few years.
For Further Research
The 1394 Trade Associations 1394b home page is located at
http://www.1394ta.com/Technology/About/1394b.htm
LaCie offers its 1394b drive products for both PC and Mac
http://www.lacie.com
SmartDisk also offers 1394b/USB 2.0 drives for PC and Mac
http://www.smartdisk.com
The data sheet for Oxford Semiconductors OXUF922 single-chip
USB 2.0/1394b bridge for IDE devices can be viewed with Adobe Acrobat. Get it
from
http://www.oxsemi.com/products/IEEE1394/oxuf922ds.pdf
Indigita offers three different FireWire 800-compliant host
adapters, including a RAID adapter. Get the data sheets from
http://www.indigita.com/products/hostadapters/index.html
Unibrain offers a FireWire 800 host adapter and FireWire 800
cables
http://www.unibrain.com
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