VOGONS


First post, by swaaye

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While playing with the Radeon 8500 on VGA output, I ran into the usual problem of fighting the monitor EDID. My LCD's EDID lacks useful things like 1600x1200 support and for some reason identifies its max resolution as 1920x1080 even though it's a 2560x1440 screen. I really like 1920x1440.

In XP the EDID can be overriden by a checkbox in the ATI drivers, but not in Win98.

I did some web searching and came across an old forum post on Rage3D saying there's an undocumented registry setting for the ATI driver to ignore DDC/EDID in Win9x.

HKLM/Software/ATI Technologies/Driver/0001/DAL
"DALRULE_CRTSUPPORTSALLMODES"
binary set to "01 00 00 00".

It works great. I was using Catalyst 6.2 at the time. Could be risky with a CRT though. Might want to assign refresh rates with HZtool first.

https://www.rage3d.com/board/showpost.php?p=1 … 989&postcount=1

Reply 1 of 13, by Tiido

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I hoped this would be able to defeat the "panning" I get from higher resolutions than 1600x1200 but unfortunately it didn't, I did get ability to use much higher refresh rates though ~

T-04YBSC, a new YMF71x based sound card & Official VOGONS thread about it
Newly made 4MB 60ns 30pin SIMMs ~
mida sa loed ? nagunii aru ei saa 😜

Reply 2 of 13, by swaaye

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Tiido wrote on 2020-07-28, 02:12:

I hoped this would be able to defeat the "panning" I get from higher resolutions than 1600x1200 but unfortunately it didn't, I did get ability to use much higher refresh rates though ~

I was getting the panning too. Even with the monitor INF installed that specifies 2560x1440 and the supported frequencies, the ATI driver prioritizes the 1080p EDID.

I wonder why it isn't entirely working for you. Is the "detect Plug and Play monitors" checkbox on the monitors panel in display properties checked or unchecked?

Reply 3 of 13, by Jorpho

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Last time I had to mess with something like that, I created an INF for my monitor and modified it accordingly, as in http://web.archive.org/web/20100906042110/htt … graphics-cards/ .

Reply 4 of 13, by darry

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I don't even get a picture on my 1920x1200 monitor (Acer VW257) at start in Windows 98SE if I don't run my FX 5900 through an EDID emulator with a simplified EDID . This is not due simply to the monitor supporting 1920x1200, as a Dell U2412M did not have that issue . The hardware EDID emulator route is more expensive, but more foolproof in the long run,

IMHO . It's definitely time somebody came out it with a home-brew, inexpensive and easily programmable EDID emulator design geared towards retro users . The closest commercial product that fits the bill is about 100 USD on a certain auction site (Aten VC060 and VC080) .

Alternatively, you can build your own, like cde did . See [HOWTO] Running DOS games natively with perfect 4:3 aspect ratio @ 70 Hz over DVI

Reply 5 of 13, by swaaye

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darry is that DVI? I think I remember your thread. Yeah DVI on old cards is troublesome. Some cards can't drive even 1280x1024. I do have a DVI EDID emulator because I use this 1440p monitor and that is often dead in the water with old cards.

My situation here is VGA though. I don't really need an emulator for that. NVidia and ATI usually let you override EDID and it will never come up blank. XP is easiest to deal with. Win9x was tricky until this registry tweak for ATI.

VGA is usually preferable to me unless I am using a dual link DVI card that can actually run 2560x1440. VGA supports higher resolutions than single link DVI (1920x1440 is nice!)

Last edited by swaaye on 2020-07-28, 04:30. Edited 4 times in total.

Reply 6 of 13, by swaaye

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Jorpho wrote on 2020-07-28, 02:46:

Last time I had to mess with something like that, I created an INF for my monitor and modified it accordingly, as in http://web.archive.org/web/20100906042110/htt … graphics-cards/ .

The problem here is ATI won't drive anything above the monitor's EDID unless you can disable that behavior. In XP they have a checkbox in the control panel. Nothing in Win9x though, which is where this registry tweak comes in.

I did spend a couple hours messing with INFs but I noticed it was always peaking at 1920x1080, which is what the EDID reports. It would do the panning 1600x1200 desktop at 1920x1080 for example.

Reply 7 of 13, by darry

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swaaye wrote on 2020-07-28, 04:21:

darry is that DVI? I think I remember your thread. Yeah DVI on old cards is troublesome. Some cards can't drive even 1280x1024. I do have a DVI EDID emulator because I use this 1440p monitor and that is often dead in the water with old cards.

My situation here is VGA though. I don't really need an emulator for that. NVidia and ATI usually let you override EDID and it will never come up blank. XP is easiest to deal with. Win9x was tricky until this registry tweak for ATI.

VGA is usually preferable to me unless I am using a dual link DVI card that can actually run 2560x1440. VGA supports higher resolutions than single link DVI (1920x1440 is nice!)

Sorry I did not notice your initial post was about VGA, not DVI . That said, VGA EDID emulators do exist as well, but a registry entry is both simpler and cheaper .

I personally have not yet moved above 1600x1200 on retro hardware and I don't know if I will any time soon . My hope is that OSSC Pro, when it comes out, will give us the best of all worlds and eliminate any reliance on VGA monitor inputs, monitor aspect ratio controls, any EDID issues and scaling compromises .

EDIT: 1920x1440 at 60Hz may be possible under single link DVI with custom timings using a reduced blanking interval .

Reply 8 of 13, by Tiido

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swaaye wrote on 2020-07-28, 02:33:

I was getting the panning too. Even with the monitor INF installed that specifies 2560x1440 and the supported frequencies, the ATI driver prioritizes the 1080p EDID.

I wonder why it isn't entirely working for you. Is the "detect Plug and Play monitors" checkbox on the monitors panel in display properties checked or unchecked?

The box used to be unchecked, but I found it had got checked again. Unchecking it (and restarting) didn't seem to make a difference. I do have a monitor INF made that specifies all imaginable resolutions and refresh rates being usable. Only way I have got past the panning has been through making custom resolutions using PowerStrip, it seems to do what is necessary to defeat the panning. I haven't looked much into what it changes in the registry, especially since I have no vanilla setup at hand to play with.

T-04YBSC, a new YMF71x based sound card & Official VOGONS thread about it
Newly made 4MB 60ns 30pin SIMMs ~
mida sa loed ? nagunii aru ei saa 😜

Reply 9 of 13, by swaaye

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Tiido wrote on 2020-07-30, 01:41:

The box used to be unchecked, but I found it had got checked again. Unchecking it (and restarting) didn't seem to make a difference. I do have a monitor INF made that specifies all imaginable resolutions and refresh rates being usable. Only way I have got past the panning has been through making custom resolutions using PowerStrip, it seems to do what is necessary to defeat the panning. I haven't looked much into what it changes in the registry, especially since I have no vanilla setup at hand to play with.

It is mysterious. I actually found that I don't even need a INF once that registry tweak is applied. The PNP detected monitor works with all resolutions. I deleted the INF out of Windows/INF/Other and removed monitor entries from device manager.

Reply 10 of 13, by swaaye

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darry wrote on 2020-07-28, 04:52:

EDIT: 1920x1440 at 60Hz may be possible under single link DVI with custom timings using a reduced blanking interval .

I got it working indeed. I had to use Powerstrip to add it, at which point I got an image but it wasn't working right. The NVidia control panel let me get CVT-RB configured though and now it's perfect. Very nice!

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Last edited by swaaye on 2020-08-02, 03:49. Edited 1 time in total.

Reply 11 of 13, by jakethompson1

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This may be a bit of an abrasive solution, but in the days of onboard ProSavageDDR VGA, and Linux X.org, I had issues with how it was detecting modes from a widescreen LCD monitor, and my ultimate solution was to "pluck" the DDC pin out of the VGA cable so that it had no choice but to obey my modelines.

Reply 12 of 13, by swaaye

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jakethompson1 wrote on 2020-08-02, 03:49:

This may be a bit of an abrasive solution, but in the days of onboard ProSavageDDR VGA, and Linux X.org, I had issues with how it was detecting modes from a widescreen LCD monitor, and my ultimate solution was to "pluck" the DDC pin out of the VGA cable so that it had no choice but to obey my modelines.

I was planning to do that but then had the thought to do some searching on whether anyone had figured out how to unlock all modes on Win98 with ATI cards. And I found that registry tweak.

On XP it's easy to override the EDID. And with NVidia cards it's easy in both 98 and XP. ATI makes it hard in Win9x.

That's with VGA of course. DVI is more tricky.

Reply 13 of 13, by darry

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swaaye wrote on 2020-08-02, 03:38:
darry wrote on 2020-07-28, 04:52:

EDIT: 1920x1440 at 60Hz may be possible under single link DVI with custom timings using a reduced blanking interval .

I got it working indeed. I had to use Powerstrip to add it, at which point I got an image but it wasn't working right. The NVidia control panel let me get CVT-RB configured though and now it's perfect. Very nice!

Nice! It's remarkable how flexible those nearly 20-year old TMDS chips and their Nvidia implementations can be .