Ok, so I got interested in poking 3Dfx Voodoo cards programmatically without drivers. So far I'm working with the Voodoo 1 emulation in DOSBox, but later on I intend to collect and experiment with real physical cards.

One thing is that to properly set up the Voodoo card, I need to query and/or configure the DAC, which is not part of the 3Dfx specification. Instead they have some sort of passthrough interface to access it.

What DACs were used in early Voodoo cards? For my specific needs right now, I only need to know about the DAC implemented in the DOSBox emulator (to find out I can experiment and/or read the source code) but that won't fly for real hardware. I have found no list of DACs in the various Voodoo cards; in particular this list does not mention it: http://tdfx.de/eng/grafikkarten_alle.shtml#Voodoo_Graphics.

Source code example (from a proof of concept code that probably incorporates constants from early Linux drivers) I've seen, mentions TI and ATT as manufacturers, and one device each; DAC_DEVICE_ATT20C409 and DAC_DEVICE_TITVP3409. The former is AT&T and I don't know if the latter is Texas Instruments. Is that all of them? I don't know if these constants are meant for Voodoo 1 or 2 or both.

I've been able to find data sheets for the AT&T one, which apparently came in two flavours [I haven't read the datasheets yet] but not TI.