The Universal Serial Bus (USB) technology lets you easily connect peripheral devices such as digital cameras, scanners, or mice to your computer. USB is designed to work with all sorts of devices, and to support hot plugging and Plug and Play. So you can connect your camera, for example, to the PC and start downloading pictures, without configuring software or rebooting.
The original USB standard offered great advantages over earlier connection technologies and its popularity spread. However, the version of USB we use most today, version 1.1, was designed with a maximum data transfer rate of 12 megabits per second (Mbps). That's speedy enough for a keyboard, mouse, and maybe a CD-ROM drive, but it's peanuts when you're working with digital video or high-speed external hard drives.
Higher speed technologies were starting to gain on USB's popularity. The most common technology for transferring digital video to a home PC has been the Institute of Electrical and Electronics Engineers (IEEE) 1394 standard. Also known as FireWire, it beats the socks off USB 1.1 with a 400 Mbps data transfer rate, which is why most digital video cameras come with IEEE 1394 (FireWire) ports, not USB.
But now there's a new version of USB, USB 2.0, with a hefty 480 Mbps data transfer rate, making it faster than IEEE 1394 (FireWire), and earning it the nickname Hi-Speed USB. USB devices have always operated at either 12 Mbps (for full-speed devices) or a mere 1.5 Mbps (for devices with lower bandwidth needs). USB 2.0 lets you use more of those devices at once and also adds a new speed, which can use the entire 480 Mbps bandwidth that USB 2.0 provides for Hi-Speed devices. Such high speeds are critical in bandwidth-hungry applications like mass storage devices, although not all devices are capable of running at 480 Mbps. For example, your USB 2.0 mouse is still a low speed device and is probably running at only 1 Mbps, but your USB 2.0 Hi-Speed CD-RW can take advantage of the new USB 2.0 high speeds and burn CDs much faster.
Compatibility with USB 1.1
Microsoft and the others who created USB 2.0 didn't leave USB 1.1 folks in the dust. USB 2.0 is fully compatible with USB 1.1 devices. The older devices work with the new bus, and vice versa.
However, keep in mind that you can't connect a Hi-Speed USB device to a USB 1.1 controller and expect it to run faster. Your computer will only run as fast as the slowest link in the chain.
In other words, all the USB 2.0 hubs in the world won't help my old laptop computer, which has built-in USB 1.1 controllers. I'll have to add a PC Card-based USB 2.0 controller, or buy a new laptop that has a USB 2.0 controller built in. Hi-Speed USB 2.0 devices will work fine when they're plugged into an older USB 1.1 controller—but they'll run at only 12 Mbps, instead of the full 480 Mbps.
The Hi Speed USB backward-compatibility means that I can start looking for new USB 2.0 devices now, even though not all of my computers have USB 2.0 capability. If you've been frequenting your local computer store, you've probably noticed USB 2.0 devices already. A number of manufacturers have USB 2.0 PCI controller cards for desktop PCs available for less than $50. PC cards for laptop USB 2.0 support are available for less than $80. And high-quality USB 2.0-compatible cables have been around for months. USB 2.0 shouldn't require you to buy new USB cables, unless you have really cheap cables that don't work well with USB 1.1, either. Certified USB 2.0 cables are available, but they're usually just high-quality USB 1.1 cables.
I can't tell you how often I've had to wait while my MP3 player downloaded a few megabytes of information at slow USB 1.1 speeds, and how much nicer it will be to use a fast USB 2.0 connection instead. I'm just waiting for a USB 2.0-compliant MP3 player to hit the market, because while my USB 1.1 player will run just fine on my new USB 2.0 hub, it can't run any faster.
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