[izacus]

Exist 20 years ago when the OS was written.

[Someone]

Even ColorSync, which the top of this thread mentioned, is older than that. It was first released in 1993 (https://en.wikipedia.org/wiki/List_of_macOS_components#Color...)

The work to remove all AT&T code from BSD started in 1989, so other parts of MacOS probably are over 30 years old, too.

I don’t think anything of the original Mac OS remains, lots of it being written in 68k assembly and pascal.