Are USB and FireWire the same?

FireWire (IEEE 1394) and USB are similar, yet very different. Both are high speed serial bus standard for computers, primarily intended for external devices. Both allow devices to be connected in series, i.e. daisy chained.

USB appears on virtually all PCs nowadays, so is very common in the Windows world. USB 2.0, the current standard, provides for a maximum data rate of 480 Mbits/second (60 MBytes/s). USB 1.1 devices run at 12 Mbits/s. By comparison modern PC hard drives run at 100 MBytes/s.

USB can in theory handle up to 127 devices, though the total cable length is limited to only 5m (USB 2.0) or 3m (USB 1.1). Up to five hubs can be connected in series, allowing for increased expansion capabilities.

FireWire is actually a trademark of Apple Computer, Inc., so the Windows world may know these devices better as IEEE 1394 devices. FireWire can be found on higher end video equipment, cameras, and scanners. Though it is not commonly built into PCs, add-on cards are readily available.

FireWire 400 communicates at 400 Mbits/s (50 MBytes/s), and the new FireWire 800 (IEEE 1394b) runs at twice that speed, approaching hard drive-like performance capabilities. FireWire handles up to 63 devices, though it is limited by a cable length of 4.5m (100m if using optical fiber).


April 2003

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