> I'm not saying Windows 9x in particular had anything super interesting going on.

Oh it did though, it is a very interesting OS. Much more interesting than it usually gets credit for.

It's a proper 32 bit OS with pre-emptive multitasking and demand paging that is enough of a chimera with DOS that it still supports DOS programs, 16 bit Windows apps, and even your old DOS drivers - side-by-side with all the new 32 bit stuff.