Zuofu wrote on 2026-09-07, 17:41:

I was building a late Windows 98 early XP era computer (e.g. from around 2003) and I noticed that connected to my RetroTink 4K, the ATI Radeon 9800 Pro I was using reports all the DOS modes (480p, 400p, mode X and mode Y) as 1024x768.

1) Check with other ATI 96xx/97xx/98xx card
2) May be problem is RetroTink 4K(config ?), it doesn't report legacy videomodes, so VBIOS made decision to enable zoom anything to 1024x768 like all modern PCI-E video cards

What way you see "reports current mode" ?

Mov AX, 0xDEAD wrote on 2026-09-07, 18:15:

1) Check with other ATI 96xx/97xx/98xx card 2) May be problem is RetroTink 4K(config ?), it doesn't report legacy videomodes, so […]
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Zuofu wrote on 2026-09-07, 17:41:

I was building a late Windows 98 early XP era computer (e.g. from around 2003) and I noticed that connected to my RetroTink 4K, the ATI Radeon 9800 Pro I was using reports all the DOS modes (480p, 400p, mode X and mode Y) as 1024x768.

1) Check with other ATI 96xx/97xx/98xx card
2) May be problem is RetroTink 4K(config ?), it doesn't report legacy videomodes, so VBIOS made decision to enable zoom anything to 1024x768 like all modern PCI-E video cards

What way you see "reports current mode" ?

It's not really a problem, in fact I want to duplicate this behavior on an older period-correct VGA card (e.g. one from 1995). I think I know what the Radeon 9800 is doing though, it's remapping all the DOS modes to XGA (1024x768x60Hz), probably because it didn't trust the built in scaling for monitors of the time. For example, here's Quake running at 320x200 on the 9800 Pro:

Here's quake running on a period correct VGA card (S3 Vision 968):

It's hard to tell, but my VGA->SDTV encoder cannot center the proper 320x200x70 Hz image, but it can center the 1024x768x60Hz image. Therefore, I would like to replicate this behavior with the PCI video card as well.

Now that I look at it some more, it seems that merely remapping 70Hz to 60Hz is probably sufficient for my TV encoder to be centered.

Zuofu wrote on 2026-09-07, 19:07:

Now that I look at it some more, it seems that merely remapping 70Hz to 60Hz is probably sufficient for my TV encoder to be centered.

I tried an experiment using 'VGA60HZ.COM', which although it works, still doesn't allow the image to be centered/full screen on my PVM. It basically treats it as a 640x480 image now, but the vertical scaling doesn't make up those 40 missing lines (e.g. it's always treating it as 320x240 with 40 black lines). I think somehow the Radeon 9800 is internally scaling all DOS video modes to 1024x768x60.