> ABIs are mostly a convention between operating system and CPU vendors, C compilers have to play by those rules just as any other compiler that wants to output

> ABIs are mostly a convention between operating system and CPU vendors, C compilers have to play by those rules just as any other compiler that wants to output code that can call (efficiently) into operating system APIs Yes and no. Unix has a very C-oriented ABI because it's written in and tied to C, and since Unix and C won other operating systems have felt pressure to make their ABI C-friendly. > we could just as well be stuck with Pascal calling conventions instead, which was used by 16-bit Windows versions If we'd gotten Pascal strings in the ABI that alone would have eliminated one major class of bugs.