Ao486 optimal configuration for a Svga 17" CRT Monitor

[AmintaMister]

Hi there, in last days I've test the "optimal" configuration for a0486 on my 31khz CRT 17" SVGA Monitor (Lg Studioworks 700S Svga, h 30 ~ 70 kHz, v 50 ~ 160 H, resolution: 1280 x 1024 / 60Hz).

My goal is to most possible close to the original Dos experience, so I've connected my MiSTer to the monitor via analog output and I've set in my mister.ini this settings:

Code: Select all

[ao486]
video_mode=1
forced_scandoubler=1
direct_video=0 ; use the scaler
vsync_adjust=2 ; minimal lag
vscale_mode=1 ; integer scaling
video_info=0 ; show resolution information for X seconds
hdmi_limited=2 ; 1 - use limited (16..235) color range over HDMI ; 2 - use limited (16..255) color range over HDMI, for VGA converters.

[video=320x200@70.1]
;video_mode=320,24,49,38,200,2,2,20,13535,0,1 ; 320x200@140.2Hz@31.4kHz DOS CGA/EGA/Adventure games with scanlines
video_mode=640,7,108,30,400,13,2,34,24708,0,1 ; 640x400@70.1Hz@31.48kHz VGA era games including 320x200, 320x400, 640x400 @70.1Hz
[video=320x400@70.1]
video_mode=640,7,108,30,400,13,2,34,24708,0,1 ; 640x400@70.1Hz@31.48kHz VGA Games including 320x200, 320x400, 640x400 @70.1Hz
[video=720x400@70.1]
video_mode=720,15,108,46,400,13,2,34,27983,0,1 ; 720x400@70.1Hz@31.48kHz DOS Text
;experimental modes
; [video=320x199@59.7]
; video_mode=640,25,130,75,398,50,29,50,27370,0,1 ; 640x398@59.7Hz@31.46kHz Jazz Jackrabbit
[video=320x240@59.7]
video_mode=640,40,96,64,480,14,2,31,26430,0,1 ; 640x480@59.7Hz Epic Pinball (temp modeline, still under development)
[video=640x480@60.0]
video_mode=640,16,64,80,480,1,3,13,23860;
[video=320x199@60.0]
video_mode=640,16,96,48,400,12,2,35,25175,0,1
; video_mode=320,-16,24,8,199,1,3,4,4170

I've also set to "variable" the frequency setting in the video settings in the menu of the core.

Then I've installed MsDos 6.22 in drive C: that auto starts mymenu.exe by Flynnsbit in drive D:

Settings the screen size to "original ratio" in the menu of the core, I get this small image with "weird" shape of texts:

C48-C05-C5-0640-479-F-9722-1955-D2-BE1418-1-102-o.jpg (118.29 KiB) Viewed 1970 times

I face this problem of "shapes distortion" also in the games. See below a "original ratio" Secret of Monkey Island with an oval clock and the "fullscreen" version with the correct circle and see also the "moon" example from Monkey Island too:

IMG-8749.jpg (223.34 KiB) Viewed 1969 times

IMG-8750.jpg (206.01 KiB) Viewed 1968 times

IMG-8747.jpg (101.21 KiB) Viewed 1968 times

IMG-8748.jpg (95.01 KiB) Viewed 1968 times

Another problem I have is that, when the core switch a resolution via the new mode changing https://github.com/MiSTer-devel/Main_Mi ... uide#ao486, I got 1-2 seconds of black screen at each change, and this is very annoying...

So, what is, with my monitor, the best strategy to achieve the original Dos resolutions with Ao486? Have I always to set "original ratio" instead of "fullscreen"? What is the difference in using "forced_scandoubler" or the "via_scaler"? Connecting the MiSTer to the monitor via direct video (I own a Hdmi to VGA dongle) would do any good?

Thanks in advance for your help!

[thorr]

I am not in front of my MiSTer right now, but my guess is you don't want Original Ratio. Try the other setting (Fullscreen). Also, you may need to adjust your monitor's sizing controls to make it fill the screen properly.

I don't recall at the moment if I solved the 1-2 seconds of black screen issue. I can't test at the moment. Probably that is the time that is needed to detect the new frequency and change the scaler settings according to the new mode.

forced_scandoubler takes the native frequency and doubles it with essentially no added lag. This works well for cores designed for regular TV's and displaying them on VGA monitors. Duck Hunt works on VGA monitors using forced_scandoubler. ao486 is not a good core to use this with. I don't know what "via_scaler" is. Maybe that is new. In general, the scaler will take any input resolution and scale it to whatever resolution you want.

I am using direct video, but it should be the same with analog. The color might be better with direct video.

[FDA]

try with max monitor resolution and vscale_mode=4 (or 5)

[mist-rich]

I can't help with your issue but just looking at the Monkey Island shots above (albeit with ratio issue), what a stunning game that was for the time Aged like a fine wine I think

[FoxbatStargazer]

It looks like you're trying to have the output resolution = input resolution. (i.e. show 640x400 in 640x400) In that case you want full aspect ratio, shaders and masks disabled.

vsync_adjust=1 might help with some of the downtime when switching resolutions, although I'm not sure how that works with every video mode having its own resolution.