Long, long ago, Ward Christensen mentioned that someone at work (IBM) told him "You can't write OS/2 programs in Assembler". Discussions followed, and eventually he gifted me the entire C programming suite for OS/2. It was quite a hefty package. I used the Macro Assembler included therein to write Forth/2, a direct threaded Forth for OS/2 written in assembler.[1]

Later, Brian Mathewson from Case Western wrote up a really good manual for it, and I actually got paid a few times for it. (Shareware, back in the day)

At one point, I had a self contained boot floppy with OS/2 minus it's GUI, Forth/2, and a bit of room left. You could load up Forth/2 and do a directory and play Bach's Toccata and Fugue in D minor simultaneously. I thought that was pretty cool.

[1] https://sourceforge.net/p/forth2/code/HEAD/tree/