IIR, C wasn't even available for most of these systems as they probably didn't have the local resources to compile their own code.

On what concerns the Spectrum range, there were some pseudo C compilers that you could type in, but there were basically toys given the 48KB space.

With the 128KB +3A model you could use CP/M, which had a better compiler available, still a pseudo C toy compiler versus the real thing on UNIX.

We only used such compilers for homework assignments.

Kids these days. If you want real control, learn to move the patch cords. Otherwise, you're stuck with only one set of opcodes.

;-)

(No, I never worked on such a system... but my mother did.)