CMOC is a 6809-generating cross-compiler for a large subset of the C language.
It generates assembly language code for the Motorola 6809 processor and
targets the Tandy Color Computer, the Dragon computer, the Vectrex video game
console, the Thomson MO and TO computers, and the OS-9 and FLEX operating
systems. It runs under GNU/Linux and other Unix-like environments like Darwin
and Cygwin. It requires the LWTOOLS assembler (lwasm) and linker, by William
Astle.

The most significant difference between CMOC and a complete C compiler is the
absence of a complete C standard library. Floats are only usable under Color
Basic. CMOC comes with a small library that serves as a starting kit.