USB Abbrev. for universal serial bus. An external peripheral interface standard for communication between a computer and external peripherals over low-cost cable using serial transmission. USB is expected to replace existing serial ports and parallel ports and to be used with keyboards, mice, printers, scanners, and removable hard drives.

USB 1.1 works at 12 Mbps with specific consideration for low-cost peripherals, supports up to 127 devices over cables up to five meters long, and includes power distribution for low-power devices. It supports daisy chaining through a tiered star multidrop topology. A USB cable has a rectangular ‘Type A’ plug at the computer end and a square ‘Type B’ plug at the peripheral end. A mini version of the plug is used for very small devices such as digital cameras.

USB provides a 5-volt supply at up to 500 mA for powering low-power devices. It is now available on virtually all personal computers and many printers, scanners, etc. It is supported by all the popular operating systems providing plug-and-play.

The USB 2.0 specification, released in 2000, allows USB to compete with Firewire, etc. USB 2.0 is backward-compatible with USB 1.1 but works at 480 Mbps. Most, if not all, modern systems support hot-swapping of USB devices.

USB drive In general, any storage device that can be attached to a computer through a USB port. The term is particularly used for small portable storage devices typically sealed in plastic. Their physical size is reflected in the various names for this type of device – thumb drive, pen drive, keyring drive. They have capacities as high as 1 gigabyte and on most modern personal computers they can be recognized as an additional drive without the need for a special driver. Storage devices of this type are increasingly used for backup, data transfer, storage of photographs or MP3 files, etc.

USB • abbr. Comput. universal serial bus, a connection technology for attaching peripheral devices to a computer, providing fast data exchange.

USB flash drive • n. Comput. an external flash drive, small enough to carry on a key ring, that can be used with any computer with a USB port.

USB Computing universal serial bus