I dug out a Matrox G450 PCI and Radeon 9200 PCI .
Heres what they did in DOS over DVI .

G450 : 640x480@60Hz over DVI with EDID emulator in line
Radeon 9200: 1280x1024@75Hz with EDID emulator in line .

Note: in all tests except the extended ones with the Radeon 9700, the EDID used has always been the same (Samsung 204B based with 1600x1200 forced at 70Hz reduced blanking) in order to avoid introducing extra variable .

I used a Matrox G200 with flat panel daughterboard before: it seems to stick to its supported VESA modes and sticks with 640x480 with borders when going lower. It did set a resolution of 656x414@70Hz when running the Triton Gravis UltraSound demo on my flatscreen TV, which isn't in the list of supported resolutions. Chasm: The Rift might also be of interest, it seems to force 70Hz (a bit off though) in 320x200 chained mode, at least on my Savage4.

Rawit wrote on 2020-06-04, 14:07:

I used a Matrox G200 with flat panel daughterboard before: it seems to stick to its supported VESA modes and sticks with 640x480 with borders when going lower. It did set a resolution of 656x414@70Hz when running the Triton Gravis UltraSound demo on my flatscreen TV, which isn't in the list of supported resolutions. Chasm: The Rift might also be of interest, it seems to force 70Hz in 320x200 chained mode, at least on my Savage4.

Thanks for the info. At this point , I have started eyeing the OSSC for my Voodoo 3 . Considering cost, i am still internally debating whether it brings enough to the table compared to my current setup (FX 5900 70Hz DVI and Voodoo 3 Extron RGB-300 DVI with 70Hz-->60Hz conversion).

The angle I wanted to pursue was looking at tools like VGA240 (https://github.com/joncampbell123/doslib/blob … hw/vga/vga240.c) and performing something likewise in reverse. Knowing that some games like Chasm can force 70Hz, I went and investigated related hardware registers of the Savage4 to see if it's possible to write a TSR that forces 70Hz output (at preferably the actual resolution). I managed to influence scaling and refresh rates through debug.com but there is where I stopped.

Rawit wrote on 2020-06-04, 14:36:

The angle I wanted to pursue was looking at tools like VGA240 (https://github.com/joncampbell123/doslib/blob … hw/vga/vga240.c) and performing something likewise in reverse. Knowing that some games like Chasm can force 70Hz, I went and investigated related hardware registers of the Savage4 to see if it's possible to write a TSR that forces 70Hz output (at preferably the actual resolution). I managed to influence scaling and refresh rates through debug.com but there is where I stopped.

That's interesting and obviously cheaper than an EDID emu . I might actually buy a cheap Savage 4 and experiment with it . I do not (yet) have the skill set to try writing to registers directly, (beyond some novice dabbling with rweverything).

At this point, I have a 70Hz solution, so I am doing this for fun, for the learning experience and to potentially generate data that could be helpful to other people's setups . So spending too much dough on this is not in my plans. That OSSC looks more and more tempting, though . 😀

Many thanks Darry for your tests. Am I correct to assume the Geforce FX 5500 should be able to accept 1600x1200@70 Hz, considering the max. resolution is 2048x1536? If so, then I suppose the BIOS is for some reason rejecting this custom resolution even though the hardware is capable of handling it.

I'm also sad the Radeon 9200 refused it. Do you have by any chance have an AGP 9250 to test this resolution with? In my case it accepted 1280x960@70Hz, although I admit it's a much lower pixel clock. 1600x1200 is an interesting resolution since it's a perfect scale from 320x200. I also tend to prefer the Radeon, as they don't have that blur effect that most GeForce 4 & 6 cards apply (with GeForce 4 being the worst).

cde wrote on 2020-07-10, 19:21:

Many thanks Darry for your tests. Am I correct to assume the Geforce FX 5500 should be able to accept 1600x1200@70 Hz, considering the max. resolution is 2048x1536? If so, then I suppose the BIOS is for some reason rejecting this custom resolution even though the hardware is capable of handling it.

I'm also sad the Radeon 9200 refused it. Do you have by any chance have an AGP 9250 to test this resolution with? In my case it accepted 1280x960@70Hz, although I admit it's a much lower pixel clock. 1600x1200 is an interesting resolution since it's a perfect scale from 320x200. I also tend to prefer the Radeon, as they don't have that blur effect that most GeForce 4 & 6 cards apply (with GeForce 4 being the worst).

I was expecting the FX 5500 to work and 1600x1200@70Hz, but it unfortunately did not . The hardware is capable, AFAIK . The FX 5500 and FX 5900 have one major difference in terms of DVI output in that the FX 5900 (also the FX 5900XT and possibly all other FX 5900s) uses a discrete TMDS chip (usually from Silicon Image or Thine) and likely has different resolution selection logic in its BIOS than the FX 5500 has in its BIOS .

I unfortunately do not have an AGP Radeon 9250 to test (as far as I know, I have some stuff in storage) . I am not crazy about Nvidia scaling either .

The reason I am not running more tests on Radeons is because the have issues in certain demos, like Second Reality .

My current "best" solution for running 70Hz in DOS is a Voodoo 3 connected to the VGA input of an OSSC, which outputs 720x400@70Hz over DVI into a CYP CP-254 that scales it to 1024x768@70Hz which is in turn scaled to 1600x1200@70Hz by my monitor (Unfortunately, the CYP CP-254 does not accept 640x400@70Hz) . This is not optimal, but preserves aspect ratio (which my monitor does not do for 640/720x400@70Hz) and still gives a sharper picture than the Geforce FX's scaling . I am waiting for a CYP SY-P293 as possible short term improvement. The long term solution is an OSSC Pro .

Thanks Darry. About the Voodoo 3, I've recently received a Voodoo 3000 2000 and I'm noticing something strange: a couple games (like Worms) and DOS text programs cause what seems like bits flipping in the VGA output (it appears as random pixels turning on and off, rather distracting). It's rather strange and I'm wondering, since this is my first Voodoo 3000, if this is caused by a fault or is this the behavior to be expected from this line of cards? Most 320x200 games and text programs do not exhibit this behavior however.

cde wrote on 2020-07-26, 08:19:

Thanks Darry. About the Voodoo 3, I've recently received a Voodoo 3000 2000 and I'm noticing something strange: a couple games (like Worms) and DOS text programs cause what seems like bits flipping in the VGA output (it appears as random pixels turning on and off, rather distracting). It's rather strange and I'm wondering, since this is my first Voodoo 3000, if this is caused by a fault or is this the behavior to be expected from this line of cards? Most 320x200 games and text programs do not exhibit this behavior however.

What a strange coincidence. I had a very similar sounding problem and fixed it with a BIOS update for my Voodoo 3 3000. Let me get back to you .

EDIT: See this thread . Voodoo 3 snow/glitches and AGP vs PCI BIOS questions I hope you can find a similar solution . Let me know if you have questions .

EDIT2: More in line with my last post in this thread, I received my CYP SY-P293 , but it was not really what I hoped for . See Re: VGA Capture Thread

cde wrote on 2020-07-26, 08:19:

Thanks Darry. About the Voodoo 3, I've recently received a Voodoo 3000 2000 and I'm noticing something strange: a couple games (like Worms) and DOS text programs cause what seems like bits flipping in the VGA output (it appears as random pixels turning on and off, rather distracting). It's rather strange and I'm wondering, since this is my first Voodoo 3000, if this is caused by a fault or is this the behavior to be expected from this line of cards? Most 320x200 games and text programs do not exhibit this behavior however.

I had the a similar issue and only managed to solve this by using MTRRLFBE.EXE in WP or WT mode.
I ended up going back to my machine's on-board Rage Pro Turbo for DOS as it didn't need anything special. However even 2D output in Windows is notably worse with the Rage unless I mess around with driver settings.

Thanks Darry and Oetker. By the way, I was mistaken: it is a Voodoo 3 3000 (not a 2000). Anyhow using MTRRLFBE did not fix it unfortunately, but flashing the BIOS to version 2.5.12SD fixed the problem completely, so that's great 😀

cde wrote on 2020-07-29, 11:36:

Thanks Darry and Oetker. By the way, I was mistaken: it is a Voodoo 3 3000 (not a 2000). Anyhow using MTRRLFBE did not fix it unfortunately, but flashing the BIOS to version 2.5.12SD fixed the problem completely, so that's great 😀

That's great news . The issue probably was not noticed much back in the day when people were mostly running 3D and SVGA resolutions on these cards .

darry wrote on 2020-06-04, 14:18:

Thanks for the info. At this point , I have started eyeing the OSSC for my Voodoo 3 . Considering cost, i am still internally debating whether it brings enough to the table compared to my current setup (FX 5900 70Hz DVI and Voodoo 3 Extron RGB-300 DVI with 70Hz-->60Hz conversion).

Just to mention in case someone stumbles upon this thread that the OSSC + a monitor with a 4:3 option & accepting 70 Hz without frame dropping (here the AOC G2590PX) has completely solved my issues. For more details see Re: Widescreen monitors and 4:3 aspect ratio compatibility thread

I was able to capture the output of a Geforce FX 5900 outputting 1600x1200 in DOS over DVI . See Re: VGA Capture Thread

The OSSC approach is really much sharper .

Indeed 😀 The OSSC approach also has the advantage of being able to switch at will between 640x480@60 Hz and 720/640x400@70 Hz, which is not possible with the EDID hack without switching EDIDs and rebooting the PC.