I don't have *C* source for a PIC macro assembler, but I *do* have some example
technology for constructing assemblers using Tcl.  I don't know if Tcl will
run on your Archimedes, though.  Using Tcl has the advantage that you don't
have to build your own symbol table management routines, and you get immensely
powerful macro facilities, such as looping, optional parameters, conditional
assembly, etc. etc.

If you want to take a look, you can get a sort of ``demonstration'' kit
of our assembler by anonymous ftp from:

        ftp.dcs.aber.ac.uk:pub/SENDIT/ASSEMBLER/assembler.tar.gz

The README file in that archive contains a ``roadmap'' to the demonstration.

Bob Gautier,
Computer Science Department,
University of Wales,
Penglais,
Aberystwyth
SY23 3DB