Plus, DOSBox is open-source, and available on most of the major software-hardware platforms.

Its use is totally hassle-free. When you run the program a DOS window opens up. If you have DOS executables on your host system, just mount the directory. The command:

mount D /path/to/the/directory

will mount an arbitrary host directory onto the D: drive of the guest system. And there you go... Here is a screenshot of an educational program I developed in the mid-1990s, running in DOSBox on MacOS X Snow Leopard:

Resistor running in DOSBox