What does the 26 pin connector on S3 cards do?

[cchisholm]

I know these are called "feature connectors" but im unable to find proper information on what exactly they do, what they connect to or specifically what i can attach to my S3 Virge.
I just bought this card off of russian ebay and im gonna be using it for a weird super socket 7 type of system, idea is bare minimum for windows XP so i can still browse the web from it for the lulz with minimal issues installing a functional browser.
Ive got a blacktop cyrix m2-233gp and 384mb of pc100, turtle beach santa cruz, etc.

If anyone knows what this can be used for, let me know. Pics included

 

[Chuck(G)]

See here for details. It's not just S3--the feature connector was present on most early VGA cards.

Mostly used for video overlay or high-end video accelerators. There were also TIGA cards that could use the connector.

 

[Unknown_K]

Some PCI graphics cards had connectors for DVD decoding cards.

 

[gertk]

I once had a Sharp TFT 640x480 LCD with 9 bit color interface (3 bit red, 3 bit green and 3 bit blue) connected to the feature connector of an PCI S3 VGA card.
The feature connector supplied 8 bits data, which normally would enter the DAC, and sync signals for the display and with some fiddling in the X windows settings I managed to get it to display direct color 8 bit RGB (connected the two lowest bits of blue together)
The display came from an old TI laptop.

 

[NeXT]

I have a TV tuner card, a frame grabber, an MPEG1 decoder and one EISA TIGA graphics card which all use the feature connector. As mentioned above the connector is limited to an 8-bit color bus, so your max color depth is 256 colors. For the above mentioned cards this was totally fine at the time but for a specialty card like the VIP interface board for the VFX1 VR headset this is a major issue due to games by the late 90's requiring 16-bit color.
Later cards like the Dxr2 MPEG2 decoder or the Voodoo 3D accelerators worked around this by using VGA passthrough instead.