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USB vs Firewire

Revised on

Originally posted on October 5th, 2001

Bugs Bunny vs Road Runner

The original USB spec defined data transfer at 1.5Mbps which was upped in version 1.1 (the one we commonly use) to 12Mbps. Now the USB group is announcing a version 2.0 of the spec which originally was hoped to deliver 240Mbps and now is expected to deliver 480Mbps.

Many people perceived this as a threat to Firewire. The core of these defenses distill down to two specific arguments: that USB isn't as well designed a protocol as Firewire (that it's 'old'), and USB isn't as fast as Firewire. Both of these claims are true to some degree.

It could be said that Firewire is a better design. It's flexible, it can handle more complex topologies, and it's communications protocols are better designed. Right now it does 400Mbps while USB crawls along at a mere 12Mbps. USB v2 comes in at 480Mbps, Firewire will almost certainly hit 1.6Gbps soon. USB is going to have to pull a rabbit out of the hat to be pushed much faster than 480Mbps without some serious design changes.

Who care? Putting this in to perspective, most peripherals fall into these classes by speed.
Slow (pointing devices like mice),
Medium (slow storage devices and scanners)
Fast (hard drives and specialized data collection devices, and video)

USB v1.1 will handle slow and medium quite well. But when it comes to the Fast, USB 1.1 can't hold on. Firewire is very qood at the fast, and the medium, but because of the design of Firewire (now anyway) the USB should rule this camp.

Who Fast Do You Wanna Go Today??

A good AV hard drive can transfer on a SCSI bus at a maximum rate of 80MBps. A more commonly used hard drive gets 16.6MBps using DMA, 33.3MBps using Mode 2 UltraATA and 66.6MBps using Mode 4 UltraATA.

USB 1.0 was 185KBps - this is crawling. USB 1.1 is 1.5MBps - still to damn slow. Firewire runs at 50MBps. That's good enough to the spec to hard drives and USB 2.0 works at 60MBps. Still not fast enough to meet the SCSI transfer rate of 80MBps. But, soon enough, Firewire 1600 will be at 200MBps. That's pretty damn good.

Neither Firewire or USB can replace SCSI or ATA. But, Firewire will be able to if it can get to 1600MBps.

In the real world, USB or Firewire can't meet these speeds because the design is all projected. Meaning these specs are are calculated under the best conditions.

Here's a list of typical bandwidth specs from

Serial port: 115kbps to 1Mbps
Standard parallel port: 115kBps
USB: 12Mbits/s (1.5MBps)
ECP/EPP parallel port: 3MBps
IDE: 3.3-16.7MBps
SCSI-1: 5MBps
SCSI-2 (Fast SCSI, Fast Narrow SCSI): 10MBps
Fast Wide SCSI (Wide SCSI): 20MBps
Ultra SCSI (SCSI-3, Fast-20, Ultra Narrow): 20MBps
UltraIDE: 33MBps
Wide Ultra SCSI (Fast Wide 20): 40MBps
Ultra2 SCSI: 40MBps
IEEE-1394: 100-400Mbps (12.5-50MBps)
Wide Ultra2 SCSI: 80MBps
Ultra3 SCSI: 80MBps
Wide Ultra3 SCSI: 160MBps
FC-AL Fiber Channel: 100-400MBps
10Base-T: 10Mbps (1.25MBps)
100Base-T: 100Mbps (12.5MBps)
1000Base-T: 1000Mbps (125MBps)

So which one is better? It depends on what you're gonna do with them. For the most part, USB is good for slower devices like mice, scanners and Zip drives. Firewire is better at the high end devices like Audio and Video editing and transfer but not good for slower speed applications.

Who wins?

I think Firewire just by a nose.





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