USB manufacturers are being deliberately confusing about this, so here's what the numbers actually mean:
| Name | Speed | Notes | |
|---|---|---|---|
| "Full speed" | USB 1.1 | 12 Mbits/sec | For a while, many products supporting this speed were labelled "USB 2.0", but they should now have been renamed to "Full Speed", or more simply, just USB. |
| "High speed" | USB 2.0 | 480 Mbits/sec | These products may have the red 'hi-speed' flash on the USB logo, and it does make a significant difference when tranferring files to an MP3 player or camera. |
| "Low speed" | USB 1.1 | 1.5 Mbits/sec | Low speed is not so much a standard, as a way of classifying devices which don't need a fast connection, e.g. mouses, keyboards, etc. |
| Firewire 400 | 400 Mbits/sec | ||
| Firewire 800 | 800 Mbits/sec | ||
Mbit/sec is I think, 106 bits per second, not to be confused with bytes per second, or with M=10243
According to Apple, 400Mbit/sec firewire can actually trounce 480Mbit/sec USB2 in terms of transferring data, so there may be protocol efficiencies to take into consideration when transferring real data
Firewire tends to be comparable in price to USB2 kit, and comes as standard on Apple computers and gadgets. PCs tend to come with USB as standard. Most pentium/athlon or later PCs have USB1.1, and more recent PCs may have USB2 as standard. Most of the new Dell computers at work seem to have both
Firewire may also be referred to by its ISO number: ISO1394b
USB has a cable length limit of 5 metres. You can extend this to 25 metres if you use 5 hubs. Firewire has a cable length limit of 4.5 metres, but can be more easily extended to 100m with specialist cables
Don't be confused by devices (mostly hubs) labelled "USB 2.0 compatible (to 12Mb/s)" as these are USB1.1 devices, using the USB2 name to misdirect their customers. Actual USB2 hubs and cards are still quite expensive (£50 maybe?) while USB1 hubs are now very cheap. The "USB2 compatible" bit means that USB2 devices can still use them, but everything drops back to slow speeds. You are unlikely to be using a USB1 hub with a USB2 device, except by mistake
