Introl C Compiler
In the early 1980s Introl released a C Compiler for the Motorola 6809 processor. The early versions were a subset of the standard "UNIX" compilers but by version 1.5 it was a very capable compiler.
Here are some quotes from the Introl data sheet
"Introl-C/6809 is a powerful C language compiler system that is designed to facilitate the development of high-efficiency software for the 6809. The Introl-C package includes a C Compiler, 6809 Relocating Assembler, Linker, Loader, Library Manager, and Standard Library. It has been in the field since early 1982 and has gained widespread acceptance among users for its reliable and comprehensive support of the C language as well as its ease of use."
"Introl-C is designed to the standard C language specification defined by Kernighan & Ritchie and supports all features of the language except fields, doubles, and the #if and the #line preprocessor directives (all other preprocessor directives, including #ifdef and #ifndef, are fully supported)."
Joel Setton scanned the following documents
Introl Data Sheet (10 Pages PDF 36K)
Command Line Arguments (2 Pages PDF 13K)
Compiler Reference Manual (86 Pages PDF 170K)
Linker and Loader Reference Manual (39 Pages PDF 71K)
Standard Library (FLEX) Reference Manual (86 Pages PDF 115K)