Sorry for playing 20 questions on this forum, but I am inept with Dosbox. What does it mean DOS mode?

Is there some way to tell Dosbox what disk drive to look in? I haven't managed to do that, if it is even possible of course.

Thank you. It has worked 😀 Much appreciated.

Is the program I want to open the wrong file type, have I made a mistake in the script, or have I done something else wrong? Thanks.