Hi Dubby,
there's really no need for apologies. It was my fault not to read the manual careful.
By the way, I've configured DOSBOX now for my needs. The PowerBASIC compiler works fine, several assemblers, too. The only thing is that some VESA modes doesn't work with my AMD Radeon 7570. That's a bit strange, because under a clean DOS (started from USB stick) they work properly. I think it's aproblem with Windows 7.
Gunther