I'm guessing just about all monitors support 640x400 for legacy purposes, but they don't necessarily display it correctly.

No one talks about the lowest resolution monitors can display, because there is no reason to. There's just never a good reason to give a LCD a that low resolution signal.

I'm also guessing testing this isn't straightforward; regardless of what the monitor supports then GPU drivers won't necessarily output that, and for low resolutions might even scale it before it gets to the monitor without you even knowing.

I mean 320x200 gets line doubled, why would you think 100x100 being a lower resolution, wouldn't be? How can you be sure your monitor is really what supports 100x100?

I have been running into this issue twice now in my past hardware projects:
- connecting Raspberry Pi HDMI output to a flat panel, then wanting to output a small video size (320x200 or 320x240 or 480x320) in order to match a specific software/game.
- producing a small HDMI output image from a FPGA that does not support high pixel clocks for higher resolutions

My 32" BenQ BL3201PT does support 320x240 and 640x480. Other flat panels I have (another BenQ, another Asus, and a third
Asus ProArt PA248QV 24") do support DOS 720x400, and 640x480, but not smaller 320x200.

Supporting nonsquare pixels with 4:3 aspect ratio is also a bit of a hit and miss. Some displays seem to support 4:3 scaling only on some specific input resolutions, but if an odd resolution is specified (e.g. EGA 640x350), they revert to a "stretch to 16:9" and disable the 4:3 option from the menu.

Yes, ideally you want square pixels instead of rectangular (stretched) ones.

ZellSF wrote on 2022-06-15, 14:30:

I'm guessing just about all monitors support 640x400 for legacy purposes, but they don't necessarily display it correctly. […]
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I'm guessing just about all monitors support 640x400 for legacy purposes, but they don't necessarily display it correctly.

No one talks about the lowest resolution monitors can display, because there is no reason to. There's just never a good reason to give a LCD a that low resolution signal.

I'm also guessing testing this isn't straightforward; regardless of what the monitor supports then GPU drivers won't necessarily output that, and for low resolutions might even scale it before it gets to the monitor without you even knowing.

I mean 320x200 gets line doubled, why would you think 100x100 being a lower resolution, wouldn't be? How can you be sure your monitor is really what supports 100x100?

Maybe the minimum resolution supported is 640x480 instead. Windows control panel displays resolutions above 800x600 and the driver control panel lists resolutions above 640x480.

I am pretty sure it isn't scaled. A Radeon GPU has scaled smaller resolutions to 1080p, but NVIDIA desktop ones at least, can output the smaller video modes (Activate windows takes more than half of the screen)

AFAIK no VGA card outputs a 320x200 or 320x240 signal. 350 scanlines is the minimum output. 320x200 and 320x240 modes are doubled to 320x400 and 320x480 output.

I prefer to have the pixels in the correct aspect ratio for the original display. 320x200 and 640x350 don't have square pixels on a 4:3 CRT.

720 x 400 for my Philips BDM4037UW, but I only use it for modern stuff.

Plasma wrote on 2022-06-15, 16:26:

AFAIK no VGA card outputs a 320x200 or 320x240 signal. 350 scanlines is the minimum output. 320x200 and 320x240 modes are doubled to 320x400 and 320x480 output.

I prefer to have the pixels in the correct aspect ratio for the original display. 320x200 and 640x350 don't have square pixels on a 4:3 CRT.

I need to say I use a HDMI to VGA convertor (which I didn't have to)

Those legacy things are probably still implemented even over HDMI. Even if it wasn't, how would you know your HDMI to VGA converter itself doesn't linedouble?

Actually with VGA a OSSC would tell you that, but most people don't have one of those lying around.

ZellSF wrote on 2022-06-15, 20:01:

Those legacy things are probably still implemented even over HDMI. Even if it wasn't, how would you know your HDMI to VGA converter itself doesn't linedouble?

Actually with VGA a OSSC would tell you that, but most people don't have one of those lying around.

I have an OSSC and a Philips 252B9 monitor. The lowest analogue RGB resolution I ever tried feeding directly (over its VGA input) to this monitor was 512x384 from a Mac IIvx and it did not work.

Running that resolution through an OSSC in passthrough mode to the monitor's HDMI input did not work either.

Line doubling that resolution to 1024x768 using the OSSC works fine on the monitor through HDMI .

ZellSF wrote on 2022-06-15, 20:01:

Those legacy things are probably still implemented even over HDMI. Even if it wasn't, how would you know your HDMI to VGA converter itself doesn't linedouble?

Actually with VGA a OSSC would tell you that, but most people don't have one of those lying around.

I don't know what linedoubling is and how it works. My information was based on the information that, when Windows is set to 100x100 resolution and a PrintScrn in pressed, the pasted screenshot comes at 100x100 resolution.

Line doubling means what it sounds like. You set a 100x100 resolution, you're outputting 100 lines of pixels (left to right). The GPU might line double that to 200 lines of pixels. This will be transparent to Windows, it will still believe it's outputting 100 lines and any screenshots will be 100 lines. But the display itself is getting 200 lines, and might not support 100 lines at all.

I'm not an expert on this, but I believe this was done to allow for using lower resolutions (for performance) on CRTs that did not support them. It's very much a legacy thing, but since there's no reason to output 100x100 as is anyway, why drop an old safety feature?

Whatever monitor I have will support whatever resolution / refresh rate I want it to with my fully programmable scaler.

Input whatever signal and convert it to something that the monitor supports.

ZellSF wrote on 2022-06-16, 13:26:

Line doubling means what it sounds like. You set a 100x100 resolution, you're outputting 100 lines of pixels (left to right). The GPU might line double that to 200 lines of pixels. This will be transparent to Windows, it will still believe it's outputting 100 lines and any screenshots will be 100 lines. But the display itself is getting 200 lines, and might not support 100 lines at all.

I'm not an expert on this, but I believe this was done to allow for using lower resolutions (for performance) on CRTs that did not support them. It's very much a legacy thing, but since there's no reason to output 100x100 as is anyway, why drop an old safety feature?

This was done on CRTs, but was it transported to LED/LCDs? I don't know. Still I see 200x200 is quite a low resolution.

BEEN_Nath_58 wrote on 2022-06-16, 18:22:

ZellSF wrote on 2022-06-16, 13:26:

Line doubling means what it sounds like. You set a 100x100 resolution, you're outputting 100 lines of pixels (left to right). The GPU might line double that to 200 lines of pixels. This will be transparent to Windows, it will still believe it's outputting 100 lines and any screenshots will be 100 lines. But the display itself is getting 200 lines, and might not support 100 lines at all.

I'm not an expert on this, but I believe this was done to allow for using lower resolutions (for performance) on CRTs that did not support them. It's very much a legacy thing, but since there's no reason to output 100x100 as is anyway, why drop an old safety feature?

This was done on CRTs, but was it transported to LED/LCDs? I don't know.

What kind of signal GPUs output to displays are kept from CRT days for compatibility reasons. There's not any good reason to change it.

Even if a GPU manufacturer did it, can you be sure all did? I mean I have no idea how you hope to get any reliable answers to your original question.

ZellSF wrote on 2022-06-16, 22:51:

BEEN_Nath_58 wrote on 2022-06-16, 18:22:

ZellSF wrote on 2022-06-16, 13:26:

Line doubling means what it sounds like. You set a 100x100 resolution, you're outputting 100 lines of pixels (left to right). The GPU might line double that to 200 lines of pixels. This will be transparent to Windows, it will still believe it's outputting 100 lines and any screenshots will be 100 lines. But the display itself is getting 200 lines, and might not support 100 lines at all.

I'm not an expert on this, but I believe this was done to allow for using lower resolutions (for performance) on CRTs that did not support them. It's very much a legacy thing, but since there's no reason to output 100x100 as is anyway, why drop an old safety feature?

This was done on CRTs, but was it transported to LED/LCDs? I don't know.

What kind of signal GPUs output to displays are kept from CRT days for compatibility reasons. There's not any good reason to change it.

Even if a GPU manufacturer did it, can you be sure all did? I mean I have no idea how you hope to get any reliable answers to your original question.

Supposing linedoubling still exists, still AMD render screens at native resolution for application resolution < 640x480. They could've used linedoubling, but they didn't! Can it mean linedoubling isn't supported on displays anymore or are they too afraid they'll lose users after they see an "Input out of range" for unsupported resolutions or are they lazy to support that resolution in driver (they don't support less than 640x480 as I said) ?

Anywys while I use an Nvidia GPU, it supports in the driver as well as the monitor to support 100x100. Again considering linedoubling posteffects occur, it's still rendering at 200x200, which is still quite low. This resolution, while not being a standard (lowest standard resolution is 160x100), will ensure legacy application compatibility, which is what I wanted to record from this thread (how low GPUs can display on monitors).

Which monitor are you using? Can't you check in the status menu of the monitor which resolution it currently thinks it is at, in stead of relying on a windows printscreen screen capture ?

weedeewee wrote on 2022-06-17, 05:42:

Which monitor are you using? Can't you check in the status menu of the monitor which resolution it currently thinks it is at, in stead of relying on a windows printscreen screen capture ?

It just reports the connection I am using, i.e. Analog

BEEN_Nath_58 wrote on 2022-06-17, 04:15:

Supposing linedoubling still exists, still AMD render screens at native resolution for application resolution < 640x480. They could've used linedoubling, but they didn't!

Again, you do not know that. Without any measuring equipment, you have no idea what the GPU does internally with the signal before sending it to your screen.

BEEN_Nath_58 wrote on 2022-06-17, 04:15:

Can it mean linedoubling isn't supported on displays anymore or are they too afraid they'll lose users after they see an "Input out of range"

1) Linedoubling itself doesn't need support on displays. As far as the display is concerned, it's just getting a higher resolution image from the GPU. More compatibility problems ("Input of range") would be caused by the GPU outputting low resolutions without linedoubling.

2) Linedoubling lower resolutions have always been the standard. There's literally no reason to drop it.

There of course a possibility that a GPU sends the signal straight to the monitor (who knows what the internal logics are for which resolutions to linedouble), but the crux of the issue here is: you don't know and neither will most people submitting data to answer you. If you really want to know the lowest resolutions many modern displays support, you need a thorough testing methodology.

BEEN_Nath_58 wrote on 2022-06-17, 04:15:

(they don't support less than 640x480 as I said) ?

Aren't you claiming you're getting 100x100 output? And you're also claiming they don't support less than 640x480? That seems rather contradictory.

There are no presets setting less than 640x480 in Windows itself of course, but I'm fairly sure that's because of recommendations by Microsoft. Nvidia doesn't show any less than 800x600, but 640x480 is supported just fine when set by an application.

BEEN_Nath_58 wrote on 2022-06-17, 06:26:

It just reports the connection I am using, i.e. Analog

That's annoying.