One of my favourite DOS things was the DEBUG.EXE command. As far as I know, it was the only debugger that allows for the creation of debug files where you could do things like debug.exe < script.dbg to do low level things like replacing a disk partition table.<p>It was a very handy method of passing around binaries in text-oriented chat systems.
I made a very in-depth video that shows 86-DOS version 0.11 being used in-context to port a piece of code from CP/M-80 2.2, to 86-DOS using RDCPM, TRANS, and the ASM. I also directly address the elephant in the room "Was CP/M code stolen for MS-DOS?" <a href="https://www.youtube.com/watch?v=Zd7T5euID1E" rel="nofollow">https://www.youtube.com/watch?v=Zd7T5euID1E</a>