Unified Display Interface

On December 20, 2005, the UDI Special Interest Group (UDI SIG) was announced, along with a tentative specification called version 0.8. The group, which worked on refining the specification and promoting the interface, was led by Intel and included Apple Computer, Intel, LG, NVIDIA, Samsung, and Silicon Image Inc. The announcement of UDI lagged the DisplayPort standard by a few months, which had been unveiled by the Video Electronics Standards Association (VESA) in May 2005. DisplayPort was being developed by a rival consortium including ATI Technologies, Samsung, NVIDIA, Dell, Hewlett-Packard, and Molex. Fundamentally, DisplayPort transmits video in packets of data, while the preceding DVI and HDMI standards transmit raw video as a digital signal; UDI took an approach closer to DVI/HDMI. Again, UDI lagged DisplayPort by a few months, which had released its finalized version 1.0 specification in May 2006. The group changed its title in late 2006 from "special interest group" to "working group" In early 2007 Intel started supporting the rival DisplayPort standard; anonymous sources stated the licensing fees associated with HDMI and incorporation of HDCP into DisplayPort swayed Intel's support. Other vendors started to use HDMI version 1.3, and it appears the UDI standard was abandoned before products were released. == Technical ==

There were two UDI implementations: "external profile" (for desktop computers and displays) and "embedded profile" (for the internal display of a laptop computer). Under the external profile, data was transmitted using three differential data pairs and one differential clock pair using the TMDS encoding scheme. Connector The external and embedded connector implementations were electrically compatible and physically similar, each with a single row of contacts, but they had different form factors and contact counts. The "embedded" implementation was only specified for the display panel interface and had a single row of 26 contacts, while the "external" implementation had a single row of 22 contacts inside a metal shield with a physically keyed rectangular cross-section, resembling the USB Type A connectors. The contacts were spaced on a pitch of (external) and (embedded). Three of the contacts were reserved for future upgrade possibilities. Transmit and receive plugs and receptacles were different physically, similar to peripheral cables with USB-A and USB-B on each end, requiring the UDI cable to be plugged in one way only. Bidirectional communication worked at a much lower data rate than that available for the single direction video datastream. ;Notes ==References==