darry wrote on 2020-06-02, 20:36:

I tried changing the preferred modeline to 1280x960 60Hz and machine will not post if that resolution is available in EDID .

Next I will try setting 1024x768@70Hz as preferred resolution . If that works, it avoids need for EDID emulator and preserves 4:3 aspect ratio.

Darry, I have hacked a HDMI cable to force 1280x960 in the EDID and it works fine at 60 Hz, 70 Hz and even 120 Hz. See this post for more information: [HOWTO] Running DOS games natively with perfect 4:3 aspect ratio @ 70 Hz over DVI

EDIT: just to mention in case someone stubles 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

darry wrote on 2020-06-02, 23:25:

darry wrote on 2020-06-02, 20:36:

I tried changing the preferred modeline to 1280x960 60Hz and machine will not post if that resolution is available in EDID .

Next I will try setting 1024x768@70Hz as preferred resolution . If that works, it avoids need for EDID emulator and preserves 4:3 aspect ratio.

1024x768@70Hz works without an EDID emulator on my monitor with this change .

Could you be more specific? I have 9600 PRO and vbios is almost identical to the one cde posted. So it's easy to do the modification from the first post (for 1280x1024@70), but otherwise I'm kind of lost. I would like to try and do your mod for correct aspect ratio (1024x768@70Hz ) but I have no idea what to find and change. I think maybe modded bios itself would suffice along with the original for comparison if you don't remember details. Thanks.

elcrys wrote on 2020-11-12, 20:43:

darry wrote on 2020-06-02, 23:25:

darry wrote on 2020-06-02, 20:36:

I tried changing the preferred modeline to 1280x960 60Hz and machine will not post if that resolution is available in EDID .

Next I will try setting 1024x768@70Hz as preferred resolution . If that works, it avoids need for EDID emulator and preserves 4:3 aspect ratio.

1024x768@70Hz works without an EDID emulator on my monitor with this change .

Could you be more specific? I have 9600 PRO and vbios is almost identical to the one cde posted. So it's easy to do the modification from the first post (for 1280x1024@70), but otherwise I'm kind of lost. I would like to try and do your mod for correct aspect ratio (1024x768@70Hz ) but I have no idea what to find and change. I think maybe modded bios itself would suffice along with the original for comparison if you don't remember details. Thanks.

I will try to find my notes or the last modded BIOS that I used and post back here .

EDIT : Apparently I no longer have a copy of my notes and test BIOS. I must have gotten rid of all that when I decided that I was not going to use a Radeon 9700 for DOs purposes . I am pretty sure that I do still have the modded BIOS on my Radeon 9700 . It will take me a few days to dig that out and dump it . It should be easy to find the original BIOS on techpowerup.com and find the differences which should allow you to replicate the mod .

If you do not see an update here within a week or so, post a reminder so I don't forget .

I just couldn't wait to brick my card so I went ahead with experiments 😀 Based on information from this thread I was able to identify complete "table" with resolutions (modelines). It begins with preferred resolution (as cde wrote) and the whole block is like this (AFAIK):

1BC 34 00 98 51 00 2A 40 10 90 13 00 00 00 00 00 00 1E - 1280x1024@75Hz
264 19 00 40 41 00 26 30 18 88 36 00 00 00 00 00 00 18 - 1024x768@60Hz
34C 1D 00 30 41 00 26 30 18 88 36 00 00 00 00 00 00 18 - 1024x768@70Hz
4C3 1E 00 20 41 00 20 30 10 60 13 00 00 00 00 00 00 1E - 1024x768@75Hz
5A0 0F 20 00 31 58 1C 20 28 80 13 00 00 00 00 00 00 1E - 800x600@60Hz
688 13 20 F0 30 58 42 20 38 78 56 08 00 00 00 00 00 1E - 800x600@72Hz
756 13 20 00 31 58 19 20 10 50 13 00 00 00 00 00 00 1E - 800x600@75Hz
8D6 09 80 A0 20 E0 2D 10 10 60 A2 00 00 00 00 08 08 18 - 640x480@60Hz
94E 0C 80 C0 20 E0 28 10 18 28 93 00 00 00 00 08 08 18 - 640x480@72Hz (VGA)
104E 0C 80 C8 20 E0 14 10 10 40 13 00 00 00 00 00 00 18 - 640x480@75Hz (VESA)

Then it was just a matter of re-writing of the first line with selected resolution/line. I successfully tested 1024x768@70Hz and 640x480@60Hz. Lower resolutions don't look very good since scaling of the monitor is much worse than internal scaling of Radeon 9600 so it's better to use the highest resolution possible. Since my AOC can do 3 types of 4:3 corrections the best looking (in terms of sharpness) is 1280x1024@70Hz - the original mod from cde. Originally I had huge problems with default 1280x1024@75Hz with my monitor - there was color noise all over the screen, picture was stretched to 2560x1024 and signal was highly unstable. Also some of the games caused monitor to show "no signal" message. This is all resolved with 70 Hz. I will try to do one more mod - force default resolution to 1600x1200 (integer-like scaling), but since I don't know how exactly is each modeline defined I will try to find something in other R3xx bioses.

I would recommend you use the second patch (see Re: Outputting 720x400@70Hz with the ATi R300 DVI output in DOS) which forces the use of the first entry of the internal table. Otherwise there's a possibility the VBIOS will decide it likes the modes from the monitor's EDID better. Have a look at https://www.analogway.com/americas/products/s … aw-edid-editor/ to determine the correct timings for your mode. By the way, you should look into making your own hacked HDMI cable with custom EDID (see [HOWTO] Running DOS games natively with perfect 4:3 aspect ratio @ 70 Hz over DVI). It's not terribly hard and you'll get the ability of using NVIDIA cards instead of ATi (as darry mentioned NVIDIA has better DOS compatibility for certain apps and games).

Thanks for the tips. I looked at that EDID editor and it looks interesting - it would be easy to modify EDID for any resolution a load it back using the tools you posted in the other thread. Problem is I want to use my monitor for other things than dos gaming and it could be problematic to have the native resolutions modified. Of course you can add certain mode into extension block of EDID, but then there is a question of forcing the graphics card to use this specific mode. I also tried 1600x1200@60Hz (R9600, DVI, Win 98) with my AOC Q3279VWFD8 and was unsuccessful - on the other hand 1920x1080@60Hz works. Anyway I have lots to think about, maybe the proper solution can be achieved only with something like OSSC or your cable.

Indeed, I don't recommend you modify your monitor's EDID, that's kindof risky and most likely would not be possible. Instead, the DVI cable hack replaces the I2C signal you get from your monitor with the own from the soldered flash. In this way, you can have a HDMI-DVI extender like pictured below for DOS gaming, and still retain your monitor's EDID for other uses. More info in [HOWTO] Running DOS games natively with perfect 4:3 aspect ratio @ 70 Hz over DVI . I would say OSSC is a better long-term solution, albeit more expensive.

I have ported the VGA BIOS 70 Hz hack for the HIS Radeon 9250 PCI, it works as expected (here with the Viewsonic VX2418-P-MHD; it has a 4:3 mode that "sticks", which is handier than monitors that reset to wide at every resolution change) . Also attached is the original (60 Hz) and new (70 Hz) ROM, as well as ATIFLASH and RaBiT.