So, problem solved. In case somebody else is interested, here's the solution: - compute appropriate 720x350 modeline using eg. this calculator: http://www.arachnoid.com/modelines/ - paste the modeline into /etc/X11/xorg.conf , Section "Monitor" - (re)start X11, and that's all Works fine with my CRT …

OK, had some closer look, and things seem to look like this: - DOSBox doesn't emulate 9x14 character box, instead it displays 8x14, ie. Hercules text mode is actually rendered using 640x350 - Hercules graphics mode is rendered using 720x348, and the closest mode supported by SDL and/or X11 on my …

OS: Linux Fedora 6, with pretty standard set of packages, including kernel-2.6.18-1.2798.fc6 and SDL-1.2.10-6.2 DOSBox version 0.74, but saw this little problem in earlier versions as well The problem is that in full-screen mode Hercules graphics mode (720x348) is rendered using 400-line mode ( …