Nice chunk of historic C code to study. This is what RMS used as a base when he moved from TECO to C. So, if you want to study Emacs without all of the clutter of the modern Emacs repo this is a great place to start.
1) unexec does not work -- the Titan version of unix is different
and I have not fixed unexec.
The more things change...
I have just fixed it recently for perl. Until libc will break it again, as announced
My current .emacs has bits that go back to my gosling emacs init file. Was it called .gosmacs? Been too long for me to remember.