Unconfirmed speculation: The linker at the time ignored letters past the first 6. The compiler prefixed the symbols with '_' to namespace them, to separate user

Unconfirmed speculation: The linker at the time ignored letters past the first 6. The compiler prefixed the symbols with '_' to namespace them, to separate user code vs compiler internals. People started writing only the part that mattered. Since either short or long name worked, it wasn't a hard rule that everything had to be shortened, but that still tended to happen. https://news.ycombinator.com/item?id=34814268 https://news.ycombinator.com/item?id=34814268