you probably have to use a scaler and/or set a higher default resolution for Dosbox. Many LCDs can't handle the default Dos resolution at fullscreen and either display black or a warning or both 😀

And how do I change the default resolution in Dosbox?

Thankss

magnifico - somewhere in the folder where you installed the main DOSBox executable (dosbox.exe) there is a file called dosbox.conf. Open it from Notepad and you should be able to change all the DOSBox settings.

But I recommend that instead of fiddling with the settings using Notepad, that you download and install one of many front-ends for DOSBox. They make it much easier to change all the settings. I recommend you try the one calld DOSBox Game Launcher.