USB is a fast, bi-directional,
isochronous serial bus designed to ease the connection of multiple peripherals including
telephony, digital communications, multi-media, and gaming devices. USB provides a simple
and inexpensive way to connect up to 127 devices to a single computer port. Keyboards,
mice, tablets, digitisers, scanners, bar-code readers, modems, printers and more can all
run at the same time. USB devices plug into any pl1atform that supports the standard, from
notebooks to desktop PCs to workstations.
the USB specification is at version 2.0 (with revisions) with a maximum
transfer rate of 480 Mbit/s. Hewlett-Packard, Intel, Lucent, Microsoft,
NEC, and Philips jointly led the initiative to develop a higher data
transfer rate than the 1.1 specification. The USB 2.0 specification was
released in April 2000 and was standardised by the USB-IF at the end of
2001. Previous notable releases of the specification were 0.9, 1.0, and
1.1. Equipment conforming with any version of the standard will also
work with devices designed to any previous specification.
The latest specification of USB is USB On-The-Go (USB-OTG).
This allows USB enabled products to be connected directly together without the need for a
PC host. New electrical specifications have been defined as well as changes to the
USB plugs and receptacles, called Mini-A and Mini-B, are also
available, as specified by the On-The-Go Supplement to the USB 2.0
Specification. As of 2006, the specification is at revision 1.2.