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What Is FireWire (and How Best to Use It)

by FJ de Kermadec
07/26/2005
FireWire
FireWire is Apple's branded name for a high-speed data serial bus they developed. Also known as IEEE-1394, this digital interface technology can move data up to 400 megabits per second (Mbps). A more recent version of this standard, FireWire 800, is capable of speeds up to 800 Mbps. Common uses for FireWire include data transfers with external hard drives, DV camcorders, webcams, and Apple's own iPod digital music player. Up to 63 FireWire devices can be connected and recognized at once. Sony has branded this technology as iLink, which also adheres to the IEEE-1394 standard.

In this article:

  1. So, What Makes FireWire Really Special?
  2. Optimizing Your Devices
  3. Create a FireWire Network
  4. Firewire Target Disk Mode
  5. Recycle Older Drives
  6. Use FireWire to Talk to Your TV
  7. Get Familiar with Developer Tools
  8. Final Thoughts

FireWire is fully autoconfigurable. Devices are placed on a peer-to-peer chain, communicate with each other and, roughly speaking, mind their own business in accordance with others. As long as you comply with higher protocol requirements (such as mounting and unmounting drives) and provide sufficient power to the chain, you can theoretically expand it to no end without suffering a meltdown.

FireWire supports branching and chaining (meaning you can plug a device into another device through which it will communicate to your computer or yet another element in the link) and does not require you to know about terminators or plugging orders; any given device A can be before, after or in between devices B and C in the chain without ill effects. There are, of course, limitations to these theories, mostly due to bugs in the firmware or circuits of some devices but, generally speaking, any user capable of putting a plug into a socket should be able to use his or her FireWire peripherals.

Interior decorators and anally retentive geeks (like me) will also like the fact that FireWire uses thin cables—even the super-thick FireWire cables are nothing compared to the large ribbons that were once commonplace—making them easy to hide, bend, and store, without risking damage to them or the devices they are plugged into.

But, aren't these considerations true of most technologies today? Hmm, maybe most, but not all. And there is a wide gap between being true on paper and being true in practice, as those of us who have played with some USB hubs know. FireWire has been doing all this for years and does it well, in part thanks to Apple's insistence that the technology should really work before you can call yourself a FireWire device manufacturer. Other technologies may offer similar features, but the very diverse market that backs them sometimes interferes with their goal of reaching true "plug and play."

So, What Makes FireWire Really Special?

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FireWire 800 is among the fastest, if not the fastest, general purpose interface you can find. It can reach speeds of up to 800 megabits per second, allowing for the transfer of vast amounts of information in very little time, which truly makes sense considering the size of some files we are now commonly manipulating and backing up. Higher transfer speeds also mean you can work directly from an external drive without experiencing a drop in performance, something that is far from being true if you work with large files stored on USB volumes—in which case dropped frames, skipped beats and oh-so-long "Saving…" progress indicators will quickly become good friends.

FireWire also supports multispeed. FireWire devices exist at speeds from 100 megabits to 800 megabits, depending on their age, purpose, and quality. Guess what? You can mix all these on a single bus and still have all devices operate at maximum speed, as the interface can change speeds on a packet-by-packet basis. Impressive, huh? We have all become so accustomed to 802:11g networks slowing down to a crawl because of the lone "b" node somewhere, that we have forgotten this scenario is not true with all interfaces. This also means you do not need to upgrade all your devices every time a better cable, port, or chipset comes along if you want to truly benefit from your latest purchases.

FireWire can operate over ultra-long distances—up to 100 meters—opening up possibilities that are unheard of with other technologies. While that may not seem immediately useful, think how nice it would be to finally put these hissing and roaring drives in an insulated closet? If you work in a laboratory of some kind, maybe you can connect to drives and devices located in another, high security room? Fear not, though, even if you don't work with flesh eating bacteria and merely own a single silent hard drive, some of the tips we are going to see today (like FireWire networking) will give you plenty of ideas to use these meters.

FireWire also provides plenty of power to the devices connected to it: up to 45W of power, more than other ports. What does this mean? This means fewer power bricks that can catch fire, fewer cables to manage, devices that charge and sync at the same time, and, as the power is significant, this means you can enjoy all this without cutting down on disk speeds, status lights, or even on-device screens. In other words, you don't have to choose between portability and features, which other interfaces usually require. Most self-powered drives, the iPod, the iSight, and dozens of other convenient little machines would not exist if it weren't for the power of FireWire.

FireWire can be Isochronous (yes, that is Iso-chron-ous). In other words, it can move streaming data in real time, putting an emphasis on speed and fluidity. Other interfaces do this, but FireWire has taken it to an art, which explains why it is used on set-top boxes, TVs, professional audio equipment, or anything that requires streaming to work really well. In those cases, FireWire guarantees the bandwidth to some devices and manages the resources allocated to other peripherals on the chain so that they can work at the best possible speed without constraining the bandwidth below what the broadcast link requires.

FireWire creates peer-to-peer networks and has always done so, meaning devices can talk to each other without requiring a computer, even on complex chains. Better yet, this feature has been here from day one, meaning all FireWire devices were built with this in mind, which is not the case of other general purpose interfaces. While you may not need your iSight to engage in heated discussions with your FireWire cup warmer (yes, there is such a device), being able to pull a cable between two camcorders and copying the data from one onto the other is a nifty trick.

Last but not least, FireWire has been designed to be efficient, no matter how many devices there are on a chain. While other interfaces degrade quickly in performance, FireWire will continue to move data along, unperturbed by all the traffic happening on the link. For example, FireWire can write and read to memory without getting the CPU in your Mac involved, meaning it draws surprisingly few resources.

Of course, all the elements we outlined are theoretical. As we all know, FireWire setups are not 100 percent perfect in real life. And faulty cables, buggy firmwares, poorly designed chipsets, cable-eating dogs, and kicking feet have brought more than one carefully crafted chain to its knees. Nevertheless, the technology is here and it has been refined over many years to form a truly exceptional standard that can benefit to home users as well as high-end professionals.

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