I found this collection recently by accident, but it’s certainly worth sharing. I was a SUPER big fan of Watcom C/C++ 10.0 back in the day as it includes not only so many targets, but also host setups making it a really great compiler for the day to target 16-bit MS-DOS, 32bit extended DOS, OS/2 16bit & 32bit, Win16, Win32, a custom 32bit Windows extender, 32bit Novel NLM’s, Autocad extensions, and no doubt many more I’m forgetting.
Head on over, and just search for Watcom:
https://archive.org/search.php?query=Watcom
Or for the heck of it:
This is great for things like trying to build Duke Nuke’m 3D, and other vintage era stuff.