VGA=Video Graphics Adapter or Video Graphics Array. VESA=Video Electronics Standards Association. DDC=Display Data Channel.
15 pin HIGHDENSITY D-SUB FEMALE connector at the videocard
|1||RED||Red Video (75 ohm, 0.7 V p-p)|
|2||GREEN||Green Video (75 ohm, 0.7 V p-p)|
|3||BLUE||Blue Video (75 ohm, 0.7 V p-p)|
|11||ID0||Monitor ID Bit 0 (optional)|
|12||SDA||DDC Serial Data Line|
|13||HSYNC or CSYNC||Horizontal Sync (or Composite Sync)|
|15||SCL||DDC Data Clock Line|
DDC1 - A unidirectional (display to host only) serial comm system which provides basic display ID and feature support information (including supported timings, display size, colorimetry and gamma, etc.) to the host. This uses pin 12 on the 15-pin "VGA" connector as a data line.
DDC2B - Adds clock (pin 15) and return (pin 11) to enable at least ID information to be obtained via an I2C interface. I2C is a bidirectional interface, but display control via DDC2B is not defined at this time.
DDC2AB - Full ID and control of the monitor via ACCESS.bus. As ACCESS.bus is basically a command and protocol definition on top of the I2C hardware interface, this uses the same lines as DDC2B. Note: Direction is Computer relative Monitor.