The pads are for external TMDS encoders from Silicon Image . AFAIK, the signal path to those encoders was digital . Later on, GPU manufacturers integrated TMDS encoders, so an external TMDS was usually no longer required .

The spec sheet for one such transmitter makes no mention of an ADC, so the signal path was most likely digital .
https://www.semiconductorstore.com/pdf/newsit … e/SiI164_PB.pdf

Great Hierophant wrote:

So on the early cards, are these DVI ports being sent true digital signals? Or are they being converted from an analog signal by a special chip? Can these DVI ports display VGA-DOS style resolutions like 320x200?

I confirm that the DVI ports are sent from digital signals, not converted from analog.
The TMDS link is completely transparent, it will just pass on anything sent to it, as long as it comes from a source with a pixel clock greater than 25.0 MHz, 24 bits per pixel (8 per R,G and B), HSYNC, VSYNC and DATA ENABLE signals. So basically it could replace the DAC.

So yes, 320x200 should be supported by the TMDS portion of the system, if the card allows it (I am sure you already know this, but it is sent as 640x400 format just like over the DAC so pixels and scanlines are doubled).

More interesting thing is replacing external ramdac with tmds encoder. Will try it one day

So in theory you could get perfect digital captures of SVGA, VGA and any lesser standard supported by the card in question. A few games and many demos may not work because they tweak or manipulate the VGA registers in a non-standard way, but most should be fine.

All Matrox G400 cards have an expansion header that can take a DVI daughter card. I have one on my Marvel G400TV and yes, it supports 320x200 modes.

NJRoadfan wrote:

All Matrox G400 cards have an expansion header that can take a DVI daughter card. I have one on my Marvel G400TV and yes, it supports 320x200 modes.

Elza has some models with external dvi module as well. Gf2 based afaik

Great Hierophant wrote:

So in theory you could get perfect digital captures of SVGA, VGA and any lesser standard supported by the card in question. A few games and many demos may not work because they tweak or manipulate the VGA registers in a non-standard way, but most should be fine.

The most interesting cards for me is voodoo 1. So lowres modes is not issue