What is FireWire? What is the Difference Between FireWire 400 and 800?

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What Is FireWire?

FireWire is one implementation of the IEEE 1394 specification originally dating from 1995. It is used to connect peripheral devices, most commonly drives and audio/video equipment, to computers. It is plug-and-play, allowing you to hot-swap (connect or disconnect devices without turning off) equipment. Because it is a peer-to-peer communication interface, it can also connect peripherals directly to one another (like a camcorder and DVD Recorder) without the presence of a PC.

The original 400 spec transferred data at up to 400 Mbits, or 50 MBytes, per second. 2002 saw the introduction of an IEEE 1394b/FireWire 800 specification offering speeds up to 100 MB/s. The specs use different cables; but are electronically compatible so you can use adapters or “bilingual” connectors that fit in both 400 and 800 version devices.

FireWire S800T, or IEEE 1394c, was finalized in 2006, though devices using it have yet to appear. It calls for FireWire 800 signals to be passed over an RJ45-tipped, Category 5e cable, generally used for Ethernet LAN (IEEE 802.3), and an RJ45 port that could detect if the connected device is Ethernet or FireWire, then use it appropriately.

FireWire Vs. USB

USB is certainly the more popular of the two: almost everything has or can use a USB port, so a PC pretty much needs to have them. Furthermore, FireWire is more expensive in terms of licensing and hardware than a USB port. Therefore, when in doubt, a manufacturer will add a USB port before they add a FireWire port. USB’s ability to go from version 1 to 2 without changing the plug or socket, while FireWire 400 connectors underwent even a minor change probably, didn’t help.

But, as explained here, USB isn’t always the best way to go. Allowing almost anything to work with anything requires USB to rely heavily on software drivers, which end up having to share processing resources with the rest of your computer.

While FireWire may have fewer applications than USB, what it does – it does better than USB can. One advantage is the aforementioned peer-to-peer connection potential. This is one reason that FireWire is preferred to USB for connections related to digital video and audio.

FireWire is also a better choice for external drives. For one thing, it often takes 2 USB ports to deliver power to a drive, unless you are using a separate power adapter. The shared power of the USB bus can cause problems as well if there are too many USB devices plugged in. FireWire can deliver enough power from a single slot, not just for a 2.5” external drive, but, at least theoretically, a 3.5” one (good luck finding one though).

The Main Difference Is Speed

USB 2.0 can theoretically move 60MB/s to FireWire 800’s 50MB/s. But the USB connection needs software and the CPU to do some of the work; a FireWire connection does not. Therefore, FireWire is about 50% faster at moving hard drive data (depending on the drive, how you use it, operating system, etc).

And that is just 400, is there even any point to FireWire 800? In a word, yes. A normal, 3.5” hard drive spinning at 7.2k RPM can use around 60MB/s of sustained bandwidth. With 400’s theoretical (i.e.: the actual speed is noticeably lower than that) bandwidth at 50MB/s, HDD speed is reduced by at least 20%. The 100MB/s you get from FireWire will cover your average hard drive speed while moving a file.

So FireWire 800 Is Good Enough?

It depends on how you use your drive. FireWire 800 can cover your hard drive’s needs as it moseys around its platters. But what about burst speed? Or how fast information can go from your system, not to the hard drive itself, but its cache? (More info on measures of hard disk drive speed here) The cache (a small amount of memory the hard drive uses to prepare and store data it thinks the system will need soon) is such a small part (less than one hundredth of one percent) that one would think burst speed is irrelevant.

It probably is less important than average speed, and has almost no impact on how long it takes to manipulate a large file, since this is done largely on the disk itself at the average speed. It is also less practical as a measurement of hard drive performance because it is heavily dependent on the motherboard and memory. That little cache can speed things up significantly when working with lots of smaller pieces of data, though, influencing things like the time taken to get all of those little programs going at start-up, or save a small file.

Burst speeds on a normal 3.5” 7.2k drive can easily exceed 150 MB/s. But again, if that is important depends on how you use the disk. Your operating system and applications, including those little start-up programs, probably live on your internal hard drive. The most common use of external drives is backing up data. If that is all you are using the drive for, burst speed is no biggie. If you use files from or save to your external drive often, then you may want to look at an eSATA disk. Particularly now that they are the same price or cheaper, and easier to find, than FireWire 400 drives, let alone the 800 variety.

If eSATA Is Better and Cheaper…

Then why get a FireWire drive? Excellent question. USB works with everything, eSATA is better at storage, so what is FireWire for? Other then where audio/video applications are concerned, it is hard to make a case for it.

But it is doggedly trudging forward though: a FireWire S3200 specification, promising 400 MB/s, has been in the works since 2007, but the earliest we will see devices with it is the end of this year. An interim S1600 standard exists, with almost no devices using it.

S3200 won’t be competing with existing USB 2.0 and eSATA 3G, however. It will be up against the new USB 3.0 and eSATA 6G connectors. To further complicate things, all three won’t just be dealing with hard drives, but are paving the way for much faster Solid State Drives, prices of which should be dropping significantly over the course of this year. The coming three-way battle for external storage connector supremacy will be covered in a coming article.