How to run old x86 DOS assembly programs in 64-bits Windows?

Answer 1

Use a DOS emulator, like DOSBox, which can be downloaded, for free, from here: https://www.dosbox.com/

However, DOSBox is more geared toward running DOS games. If you can't get your old DOS program to run in DOSBox, try the more sophisticated, general-purpose VirtualBox, which can also be downloaded, for free, from https://www.virtualbox.org/

One caveat, though, with VirtualBox: MS-DOS is NOT free, and DOES NOT come with VirtualBox! You either need to have a licensed copy of MS-DOS (likely on floppy disks!), and install it ... OR, you can try running your DOS program under FreeDOS (which can be downloaded, for free, from http://freedos.org/). You would have to install FreeDOS in VirtualBox, but you wouldn't have to worry about those pesky, old copyrights or floppy disks!

Best of luck to you, fellow DOS user!