VOGONS


DOSBox 15 kHz/240p tips

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First post, by bjt

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(Crossposted from the Arcade Controls forum)

Spent a while playing around with various versions of DOSBox. DOSBox 0.74-3 (latest stable) seemed to work the best, the forked versions with VSync & Direct3D exhibited various issues.
My objective was to get pixel-perfect, unfiltered output with as smooth scrolling as possible and no tearing. Output at 320x240 @ 60Hz to a 15KHz display using CRTEmudriver on ATI 5450 under Win 7 Embedded.

fullscreen = false # prevents freeze on startup
fulldouble = true # needed to prevent tearing
fullresolution = original # selects 320x240
output = ddraw
machine = svga_s3
aspect = false
scaler = none
cycles = fixed 40000 # needed as max mode causes slowdown

I use multimonitortool to select 320x240 mode before starting DOSBox, and change back to 640x480 interlaced after DOSBox quits.
For some reason, setting fullscreen = true causes DOSBox to freeze on startup. For this reason I start DOSBox in windowed mode, then send ALT-ENTER after 5 seconds to select fullscreen mode. I use an AutoHotKey script for this.

It works surprisingly well, albeit with letterboxing as most DOS games are only 200 high. CGA and EGA games run completely smooth (as they were 60Hz refresh originally), 320x240 VGA mode X is smooth too. VGA 320x200 games have the odd small stutter, as they are 70Hz.

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Reply 2 of 8, by maxtherabbit

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Bat top sticks make me irrationally angry

Reply 3 of 8, by Anapan

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I made some TSR bios fonts for displaying text mode 80x25 correctly in 640x240 and 320x240 resolution:
Re: Force 320x200(ish) VGA text mode
I use these in my cocktail cabinet with a 36" CRT.

norefuge7.png
attitude1.png

Reply 4 of 8, by theelf

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bjt wrote on 2020-08-06, 15:16:
(Crossposted from the Arcade Controls forum) […]
Show full quote

(Crossposted from the Arcade Controls forum)

Spent a while playing around with various versions of DOSBox. DOSBox 0.74-3 (latest stable) seemed to work the best, the forked versions with VSync & Direct3D exhibited various issues.
My objective was to get pixel-perfect, unfiltered output with as smooth scrolling as possible and no tearing. Output at 320x240 @ 60Hz to a 15KHz display using CRTEmudriver on ATI 5450 under Win 7 Embedded.

fullscreen = false # prevents freeze on startup
fulldouble = true # needed to prevent tearing
fullresolution = original # selects 320x240
output = ddraw
machine = svga_s3
aspect = false
scaler = none
cycles = fixed 40000 # needed as max mode causes slowdown

I use multimonitortool to select 320x240 mode before starting DOSBox, and change back to 640x480 interlaced after DOSBox quits.
For some reason, setting fullscreen = true causes DOSBox to freeze on startup. For this reason I start DOSBox in windowed mode, then send ALT-ENTER after 5 seconds to select fullscreen mode. I use an AutoHotKey script for this.

It works surprisingly well, albeit with letterboxing as most DOS games are only 200 high. CGA and EGA games run completely smooth (as they were 60Hz refresh originally), 320x240 VGA mode X is smooth too. VGA 320x200 games have the odd small stutter, as they are 70Hz.

S3NAd7Xh.jpg
ARQyFKMh.jpg
faUZ76wh.jpg
GWIjJljh.jpg
lFwmyygh.jpg

Hi, my sony tritron can do up to 66hz, and vga 70hz dos games run almost perfect

did you try to push limits with modelines beyond 60hz? maybe you have luck too

Reply 7 of 8, by GnoM

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Is it possible to scale dosbox to 640x240 somehow?

Reply 8 of 8, by theelf

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GnoM wrote on 2022-12-14, 11:15:

Is it possible to scale dosbox to 640x240 somehow?

Hi, what kind of GPU you have?

If is new, you can use opengl,i think will fill screen

I have a thin client connected to CRT TV using scart, ati x1300 and i did a custom build of dosbox with custom scaling for surface, 2x width, 1x height