TFT Guide Part 3 - Digital Interfaces

Comparison And Summary

Standard P&D
Digital Flat Panel
Digital Visual Interface
Owner VESA (V ideo E lectronics S tandards O rganization) DFP Group (D igital F lat P anel Group) and later VESA DDWG (D igital D isplay W orking G roup)
Revision / Date 1.0 / Jun 06, 1997 1.0 / Feb 14, 1999 1.0 / Apr 02, 1999
Web page
Workgroup leader VESA Compaq Intel
Compatibility Own standard P&D compatible (adapter possible) P&D and DFP compatible (adapter possible)
Transfer protocol TMDS (PanelLink) TMDS (PanelLink) TMDS (PanelLink)
Max. pixel rate (Dot Clock) 165 MHz x 1 165 MHz x 1 165 MHz x 2
Max. number of channels 3 channels (single link) 3 channels (single link) 6 channels (dual link)
Color depths 12 or 24 bit 12 or 24 bit 12 or 24 bit
Max. Resolution SXGA (1280 x 1024) SXGA (1280 x 1024) HDTV (1920 x 1080)
Optional transfer of other signals possible using the same connector Analog VESA video, USB, IEEE 1394-1995 No, only digital video Analog VESA video
Digital Connector P&D-D (30 pin) MDR20 (20 pin) DVI-V (24 pin)
Analog/Digital combination connector P&D-A/D (30 + 4 pin) No DVI-I (24 + 4 pin)
Connector width 40.6 mm 33.4 mm 37.0 mm

Table 2: Comparison of the three most important digital interfaces.

If you compare P&D, DFP and DVI carefully, the conclusion is fairly simple: The expensive Plug&Display standard is practically obsolete and DFP limits the resolution to 1280 x 1024 pixels and only allows the connection of digital TFT displays. This means that monitors with analog VGA connectors can't be connected because a digital-analog connector is far too complicated). Matrox, ATI and Number Nine have already announced products with DVI connectors. DVI uses not only the same protocol as P&D and DFP, it is also electrically compatible. This means that adapters are possible to use all three digital standards, although the maximum resolution may not exceed 1280 x 1024 pixels. This would require a second link (dual link ), which, of course, only DVI incorporates. Graphic board manufacturer Number Nine has eccectively demonstrated the inherent level of 'interconnectivity' with its SR9 card that is based on a Savage4 chip from S3 . The user can select which of the three connections - P&D, DFP or DVI - he wishes to use as an optional extra. In our opinion, the future belongs to the Digital Visual Interface (DVI) interface. DVI not only allows high resolutions, it also enables the connection of analog devices (using an adapter if necessary). Beyond that, DVI has enough support from the industry to prevail on a long-term basis.

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