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MiSTer-devel / ao486_MiSTer

ao486 port for MiSTer
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No VGA output? #6

Open cr4zymanz0r opened 5 years ago

cr4zymanz0r commented 5 years ago

ao486 v190308

I connected to a Dell CRT monitor to the VGA port on the IO board. This monitor works fine in DOS games on a PC. It work on the menu and other low res cores when I enable the 'forced_scandoubler' option. Once the load the ao486 core it the monitor loses signal. I even tried with the 'forced_scandoubler' off and it was the same result once the core was loaded

sorgelig commented 5 years ago

ao486 outputs HDMI resolution through VGA on this core. So you need to set a compatible to your monitor video mode in MiSTer.ini

cr4zymanz0r commented 5 years ago

Oh, I assumed that would only be the case if 'vga_scaler' in MiSTer.ini was enabled. However using the HDMI resolution isn't true to original hardware over VGA. No scaling is needed when using a CRT PC monitor. Also, most (all?) things in DOS run at 70hz which there appears to be no option for in the HDMI resolutions since they cap at 60hz.

elexor commented 3 years ago

With the newest updates this core seems to output an offspec vga signal that works with my pc crt 31.5khz. https://www.youtube.com/watch?v=WaDTQ3TU_rc

it's not hdmi resolution the signal is not working 100% correctly. dark bands in some 2d dos games. fuzzy video. when you switch core frequency the signal is effected in strange ways.

Could this output be fixed up? would be nice to use ao486 with vga monitors at native resolutions. vgascaler never gets you perfectly scaled pixels on a pc crt.

sorgelig commented 3 years ago

This core doesn't officially output VGA if vga_scaler isn't enabled. Due to variable video clock pixels will be uneven on VGA if original video is output. Blanking are not normalized as well since it's not supposed to be output directly.

elexor commented 3 years ago

Any plans for a proper vga output? or is it not possible or practical?

sorgelig commented 3 years ago

only with vga_scaler=1

thorr2 commented 3 years ago

If we have to go through the scaler, can you add a feature that detects the signal that it is trying to do (640x480, 640x400, 800x600, etc.) and tell the scaler to set that resolution on the fly? Using one scaled resolution for everything does not look right and this would fix that I would think. Thanks!

thenoble1 commented 3 years ago

Been struggling to deal with this issue for days now as some cores are not working properly if I turn VGA scaler on so I have to constantly swap back and forth between ini files to make this work.

thorr2 commented 3 years ago

You can turn it on and off for each core in the INI file under a [section] with the core name in the brackets.

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Been struggling to deal with this issue for days now as some cores are not working properly if I turn VGA scaler on so I have to constantly swap back and forth between ini files to make this work.

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elexor commented 3 years ago

There needs to be an option to disable the scaler and just output native resolution over hdmi this will make vga_scaler useful for crt monitors the scaler is always trying to correct aspect ratio this is not needed and does not perform well at low resolutions like 640x480.