ASL STEM

Definition

(Universal Serial Bus) a standard way of connecting peripherals to computers, designed to replace serial, parallel, SCSI, and other kinds of ports. USB 1.0 provides a data rate of 12 million bits per second (Mbps), slower than its rival, Firewire (IEEE 1394), but cheaper to implement. USB 2.0 (“Hi-Speed USB”) achieves 480 Mbps and is fully compatible with the previous version. The maximum cable length is 5 meters (16 feet). Any USB port can be expanded into many ports by using a USB hub, and long cable runs can be achieved by inserting a hub every 5 meters (5.5 yards). Unlike parallel, serial, and SCSI ports, USB ports allow devices to be plugged in and unplugged while the computer is running. Also, USB ports provide a limited amount of electric power to external devices, so that in many cases the peripherals do not need their own power connectors. USB ports are even used to power lights and speakers.

Source: Downing, Douglas, et al. Dictionary of Computer and Internet Terms. 10th ed. New York, 2009. Print.