So I recently took at broad look at some of the old C compilers and wrote an article about it. One interesting thing of note is a lot of compilers in the mid 70s compilers like the Small-C compiler actually only compiled a subset of the C programming language. This was because the 8-bit systems were much more resource constrained the then PDP-11s that C was developed on, and C was difficult to compile. It's hard to believe computers once struggled to run C code, and that definitely contributes to why you see more Pascal, Assembly, and Basic during that time period