VGA Feature Conector

Does anyone know how the VGA video feature connector operates? I would like to know which of the pins are inputs, which are outputs, and which are bidirectional (if any - and how the direction is selected).

I have found a pinout for the connector:

Video Feature Connector Pinouts.

Pin     Name   Function 1       PD0    Dac Pixel data bit 0 2       PD1                   bit 1 3       PD2                   bit 2 4       PD3                       3 5       PD4                       4 6       PD5                       5 7       PD6                       6 8       PD7                       7 9       -      Dac Clock 10      -      Dac Blanking 11      -      Horizontal Sync 12      -      Vertical Sync 13      -      Ground  14      -      Ground 15      -      Ground 16      -      Ground 17      -      Select Internal Video 18      -      Select Internal Sync 19      -      Select Internal Dot Clock 20      -      Not Used 21      -      Ground 22      -      Ground 23      -      Ground 24      -      Ground 25      -      Not Used 26      -      Not Used 

And I assume that pins 1 - 12 are outputs, and 17 - 19 are inputs. Is this correct?

The reason is this - I have a Rombo Media Pro+ video digitising card. It chroma keys its output into the vga monitor signal. However, although it is supposed to work with an ET-4000 with Hi-colour RAMDAC, the colours on screen behave as if the top 2 bits of colour information are missing, and red, green, blue signals are swapped around. Rombo has suggested that this may be due to insufficient buffering on the feature connector outputs, and is happy to sell me a buffer device for 50 pounds. I would rather save about 45 pounds, and build my own. I assume it would require (for example) a 74F244 buffer IC (or two).