Sunflux wrote on 2022-03-15, 21:11:
I guess I was led off the mark by this old thread: […]
I guess I was led off the mark by this old thread:
Geforce 2 recommendation request
the problem is that the video signal from the DVI is general very poor because its goes through the RAMDAC and then to the SiliconImage Chip to get Digitalized again. like on most other cards from this time
My searches didn’t lead to anything more informative.
That guy has an issue with information literacy.
The typical Panellink/DFP/DVI tmds encoder of the day was the Sil164, and its datasheet was publicly available even in 2010. He could have just gone and looked it up and seen that it uses a 24bit parallel bus. My earliest card with a DFP connector is a savage 4 with a SIL140. You can find a VT8501(MVP4) datasheet where the 24bit connection to the encoder is listed as well.
The same is true for older cards, those with an external VGA ramdac. Something which vanished in the mid 90s with the introduction of the Trio64V. My Tseng ET4000s have either an ST micro ST1703, chrontel CH8398 or ICS Gendac ICS5342 which all have 8/16bit parallel pixel busses. Again datasheets are available.
_All_ external TV, DFP and DVI encoders, as TV/VGA decoder chips, all talk to the display engine over a digital bus. The same is true for directly attached LCDs, and for the VIP port, or VESA feature connector. Back in the 2000s, this was a parallel bus, usually 8/16/24bits wide. It's only in the last 15-20years, with PCIe and MIPI, that this turned into digital serial busses.
Digital parallel busses are easy, especially for the 100 or so MHz that you need if your bus is full width and you are not using higher than 1920x1200 resolutions (single link DVI is FullHD with reduced blanking at 165MHz max). Analog busses are hard to route and shield, as any interference directly influences the displayed colours. Internally, on the die, it is the same. All is digital and it is the DAC part that is hard to keep linear and clean as processes shrink.
-- The guy who came up with modesetting, a misnomer for structured display driver development, which was borne out of a desire to rid linux display drivers of BIOS/Int10 dependence.