UDI: The Unified Display Interface Standard is a lower cost version of DVI/HDMI video interfaces. However after the initial standard was released in 2005 and upgraded in 2006, support for the interface was dropped in 2007 in favor of the DisplayPort interface. No products were ever produced using the UDI specification and as of 2010 appears to be unsupported.
UFS Bus: The Universal Flash Storage card is an external Flash card with a estimated speed of 3Gbps (per lane), and was released by the end of 2010.
UICC: The Universal Integrated Circuit Card; a SIM card for a different application
USB Bus: The Universal Serial Bus provides two-way communication between the PC and peripheral devices, over a Differential 4-wire serial interface cable [Differential data, and Power/Ground] up to 3-5 meters away. A Slow-Speed mode of 1.5Mbps is used for devices such as mice. Full-Speed mode is used by most devices and allows a transfer rate of 12Mbps. High-Speed mode allows rates of 480Mbps.}
Utopia Bus: The Utopia Bus Standard is the Test & Operations Physical Interface for ATM [Asynchronous Transfer Mode].
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An alphabetic listing of released interface buses.
The links point to pages that describe the physical and electrical interfaces.