A History of the USB Standard

A History of the USB Standard

Universal Serial Bus (USB) is a serial bus standard for connecting peripherals to a host. It was designed to allow peripherals to be connected using a single standardized interface and to improve plug and play capabilities by allowing peripherals to be connected or disconnected without having to reboot the computer or turn the device off. This bus can connect devices including mice, keyboards, gaming controllers, scanners, digital cameras, printers, digital media players, flash drives and external hard drives. USB has become the standard connection method for the majority of consumer electronic devices. To date, billions of these devices have been introduced into the consumer electronics market.

The USB Implementers Forum, Inc. (USB-IF) is a non-profit corporation founded by leading companies in the computer and electronics sectors. The organization was formed to provide a support group and forum for the advancement and adoption of USB technology. The Board of Directors is currently comprised of the following companies: Hewlett-Packard Company, Intel Corporation, LSI Corporation, Microsoft Corporation, NEC Corporation and ST-Ericsson.

USB 1.0 and 1.1
The USB 1.0 specification was introduced in 1994 with two data rates, Low-Speed (1.5 Mbps) and Full-Speed (12 Mbps). It was designed to replace the myriad of connectors at the back of PCs and simplify software configuration of communication devices. The 1.1 specification was released in 1998 and was the earliest revision to be widely adopted.

USB 2.0
The USB 2.0 specification was released in 2000 and was standardized by the USB-IF in 2001. Several companies led the initiative to develop a higher data transfer rate of 480 Mbps, about 40 times faster than the 1.1 specification. Also known as Hi-Speed USB, 2.0 expanded the range of external devices that could be used on a computer. And, offered backward compatibility with previous generations.

USB On-The-Go
Many USB devices are portable, and there is an increasing need for devices to communicate directly with each other without a computer. The On-The-Go Supplement makes it possible for peripherals to communicate directly with each other. On-The-Go features include:

- Limited host capability to communicate with selected USB peripherals
- A small connector appropriate for the mobile form
- Low power requirements for preserving battery life
- Ability to be either host or peripheral and to dynamically switch between the two.