USB

Universal Serial Bus (USB) is a way to connect peripheral devices to computers. It replaces the functionality of serial and parallel ports, including keyboard and mouse ports.

USB uses a bus topology, which means peripherals can be daisy-chained together or connected through hubs. Up to 127 devices may be connected together at one time, and devices may be connected and disconnected while the computer is in operation (hot-swapping).

To use USB peripherals, your computer must have either built-in USB capability or a USB expansion card installed. Your computer's operating system must be able to support USB as well.

USB devices are self-identifying, and USB is Plug-and-Play compliant, which means that installation and configuration of USB devices should be relatively easy. The current standard, USB 2.0, is backwards compatible with the earlier 1.0 and 1.1 standards. USB 2.0 supports bandwidths of 1.5Mbps, 12.5Mbps, and 480Mbps.

Finalized in 2001, USB 2.0 is a complete overhaul to the Universal Serial Bus input/output bus protocol which allows much higher speeds than the older USB 1.1 standard did.

USB 1.1 allowed a maximum transfer rate of 12Mbits/second. That rate is now called 'USB.' Though some manufacturers label their products Full-Speed USB. Note that this seems a bit deceptive. It�s easy to mistake Full-Speed for Hi-Speed.

You won't be fooled from now on as you now aware that Full Speed USB is only 12Mbits/second where Hi-Speed USB mode is capable of a much faster 480Mbits/second.

As an aside, USB mice and keyboards need only 1.5Mbits/s to function. That performance level is also named 'USB' by the USB Promoter Group.

To sum it up, USB 2.0 specification incorporates three speeds: Hi-Speed, Full-Speed and Low-Speed. You as a consumer don't need to figure out all the jargons. Just keep in mind that only 'Hi-Speed USB' and 'USB' host and devices exist.

Peripherals that make use of USB connections include digital audio devices, telephony devices, cable boxes, printers, keyboards, mice, joysticks, digital cameras, and scanners.

For more information about USB, including technical specifications, see:

http://www.usb.org