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LCD not accepting VESA modes over 800x600

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First post, by Ampera

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Using a DELL LCD panel, this is probably an exhaustive question, but the interesting thing I have noticed is that when displaying VESA modes of 320x200 or 400x300, it will say in the panel's menu that the video mode is 740x400 or 800x600 respectively, even thought the video mode selected is not. I have tried 3 separate panels and they are all unable to display VESA modes over 800x600, EXCEPT for the mode 1152x864. This mode, for
some strange reason works on all 3 panels.

This mode is only available through the Trio32 (On my Diamond Multimedia Stealth SE) S3 drivers for Windows 3.11 and can not be found on any other systems, not even Win9x (Although it is available on my modern computer). And when looking here: https://en.wikipedia.org/wiki/VESA_BIOS_Extensions it doesn't appear to even be a VESA mode. I don't get it. It appears to be an XGA+ mode though.

I am confused by this, is it the refresh rate that is the issue? It's accepted LITERALLY everything else, and this panel is fairly good with odd refresh rates. Apologies for the tired question, but what could I do to rectify this? This also happens on my Mach64 integrated from a couple IBM servers. On SOME video modes (Not when a proper Linux environment is installed) this happens there too, like when trying to install Ubuntu.

Strange.

Reply 1 of 5, by yawetaG

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Which Dell LCD panel? The model number should be written on a sticker on the back of the screen.

I know my Dell flatscreen fails to display certain VESA modes properly. 1152x864 might be the LCD's native resolution, by the way.

Reply 2 of 5, by Ampera

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yawetaG wrote:

Which Dell LCD panel? The model number should be written on a sticker on the back of the screen.

I know my Dell flatscreen fails to display certain VESA modes properly. 1152x864 might be the LCD's native resolution, by the way.

It's not. It's 1280x1024 @75Hz : 1908FP

Reply 3 of 5, by yawetaG

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Found the manual: 1152x864 is one of the preset display modes (page 6 in the manual).

I assume the higher resolutions work properly on newer systems?

Reply 4 of 5, by Ampera

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But the issue isn't a higher resolution, it's ANY resolution except 1152x864 including 1024x768. That is the strange thing.

And yes, all resolutions work on Digital and modern analog systems.

Reply 5 of 5, by Jepael

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On old systems 1024x768 was interlaced at 43 frames per second (86 fields per second), I don't think monitors handle this, unless they specifically say they support the interlaced mode. TVs support it rather well. When you have correct drivers the of course it should detect the monitor supports 1024x768 @ 60 Hz progressive scan and use that resolution, or with correct drivers it forces it to that resolution.

And there is very simple reason the 320x200 mode looks like 720x400 to the monitor : the horizontal and vertical timings are identical as the 200-line mode is double scanned to 400 lines and pixels are wider, and the monitor cannot tell how many pixels you have per line. It cannot possibly know the difference between 320x200 graphics mode and 720x400 text mode, and it has to assume you are in 720 wide mode to display DOS text mode correctly without skipping pixels.

Same thing with 320x240 tweaked mode, to the monitor it looks like 640x480 mode.

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