"Only text-based “standard I/O” DOS programs are usable in this environment, so if you run a program that switches to graphics mode or writes directly to video

"Only text-based “standard I/O” DOS programs are usable in this environment, so if you run a program that switches to graphics mode or writes directly to video memory, don’t expect to see anything." OK. Let's test some DOS-based develpment tools (e.g DJGPP) with it...