Tandy/Radio Shack licensed a BASIC for the 6809 from Microsoft called Color BASIC. Later there was Extended Color BASIC and Disk Color BASIC. All of these programs came in ROM with the Color Computer. When the Color Computer 3 came out Microware created a patch called Super Extended Color BASIC.
The Color Computer Unravelled series of books published very good commented disassembles of these programs. In 2009 I transcribed those disassembles to reassemble to perfect binary copies of the original ROMs. I used the Mamou assembler, but these source files should be able to be massaged to work with any assembler.
Click here to download the source.