USB 2.0 at a Glance

The Universal Serial Bus (USB) has been a part of nearly every PC shipped since the late 1990s, connecting computers to mice, digital cameras, scanners, handhelds, and other peripherals. But until recently, it wasn't fast enough for camcorders, CD-RW drives, or hard drives. USB 2.0, available on most of today's desktop computers and laptops, raises the data-transfer speed from 12 Mbps to 480 Mbps and brings the technology to the most demanding peripherals.

History

USB was conceived in 1993 by Compaq, Digital Equipment Corp. (DEC), Microsoft, and NEC. By 1995, they had created the USB Implementers Forum to replace the hodgepodge of existing I/O ports with one easy-to-use technology.

In 1996, the forum approved the USB spec. In 1998, it was released as a standard, and Microsoft included USB drivers in Windows 98. By this time, most desktops had at least one USB port, and the technology had worked its way into most new peripherals. USB could transfer data at 12 Mbps, making it 10 times as fast as a basic "compatibility mode" parallel connection and 80 to 100 times as fast as a serial connection. But it still needed more speed to work with video cameras, network adapters, and external optical and hard drives, which relied on SCSI or FireWire.

In 1999, the group started to work on a 480-Mbps version. In mid-2000, the IEEE finalized USB 2.0, also referred to as Hi-Speed USB (not to be confused with Full-Speed USB, the new name for 12-Mbps USB 1.1). Now that Intel has built USB 2.0 support into CPU chipsets and Microsoft has added support to Windows XP Service Pack 1, most PCs are equipped to use the technology.

Pros and Cons

The best part about USB is that it's everywhere. Some 400 million devices shipped with USB in 2002, as opposed to 60 million with FireWire, according to In-Stat/MDR. Most of today's USB 2.0 peripherals are high-speed devices, such as Maxtor's external hard drives and TDK's portable CD-RW drives. But the technology also works with low-speed devices, like mice. Most new mainstream PCs have at least one USB 2.0 port, which lets you connect not only dozens of new USB 2.0 devices but also the thousands of USB 1.1 devices on the market. Connecting a USB 1.1 device to a USB 2.0 port, however, will still yield a maximum throughput of only 12 Mbps.

USB devices are less expensive than FireWire devices: A USB 2.0 hard drive costs about $20 less than a FireWire drive. That's because USB uses a host/slave architecture: When you connect a USB device, the computer, or host, controls the transfer of data to and from the peripheral—the slave. The peripheral contains less I/O hardware than a FireWire device and is consequently cheaper to make. But this also means you can't use USB without a PC, so you can't transfer video directly from a camcorder to a digital television.

The Future

USB 2.0 will eventually replace USB 1.1, but its future is unclear. Several companies have been working on wireless USB protocols—including Intel and Cypress Semiconductor Corp., which will soon make its silicon available to manufacturers. But for the time being, USB remains firmly tethered to your desktop.