[guenthert]

I don't think the Small-C compiler was all that popular with professionals (or even hobbyists). It was incomplete, slow and produced (on the Z80) poor code.

C was indeed not ideal for 8 bitter (hence the astonishment around this topic). CP/M istself was written in PL/0 (I suppose with a sprinkle of assembler). Macro assemblers were popular then for shrink-wrap software. Custom software was often done in BASIC.

Professionals used cross compilers (or cross assemblers) when they had a chance. Microsoft BASIC e.g. was developed on a PDP-10.