This is a very old piece of software found in the C User's Group Archive.

Located here:
   https://archive.org/details/C_Users_Group_Library_Walnut_Creek_August_1994

The vast majority of this Git repo is taken directly from there.  The first
commit is an exact copy from the CUG archive, with the second commit removing
trailing characters leftover from the CP/M filesystem.  Later commits make
the code compile without warning on GCC, and add some new features.

I have contacted William Colley, and he has granted permission for his code to
be released under GPL.  My modifications are licensed the same.  The GPL
supercedes all other copyright notices noted in the code or manuals.  (Other 
versions of the assembler that exist that were derived from other copies
of CUG-149 are, of course, not bound by the GPL. )

Herb Johnson maintains an different (non-GPL) version on his webpage here:
    http://www.retrotechnology.com/memship/a18.html

Notes:

- My interest in this code centers around the 1802 processor.  I have not tested
  the 68xx assembler, but provide the original source here, as this is hard to 
  find.  These files have been moved to 68xx.

- This code is written in K&R C.  Some minor things have been changed to make it
  compile on gcc without a lot of complaint.

- To build type 'make' and it should build if you have GCC available.  I have't
  created a 'configure' script, or anything like that, but my guess is if you
  are trying to assemble code for a 40 year old CPU, you probably know how to 
  modify the Makefile.

- I have not tried to build or use the hextos utility, as I currently have no
  use for SREC format, and would be unsure if it is correct.


The original README from the CUG Archive follows.

/*
	HEADER:		CUG149;
	TITLE:		Cross-Assemblers (Portable);
	FILENAME:	READ.ME;
	VERSION:	1.0;
	DATE:		09/25/1985;

	DESCRIPTION:	"This is the general introduction file for the portable
			versions of the 1805A, 6801, and 6805 cross-assemblers.
			Each assembler is explained in detail in its header
			files.";

	SEE-ALSO:	1805A Cross-Assembler (Portable),
			6801 Cross-Assembler (Portable),
			6805 Cross-Assembler (Portable);

	AUTHORS:	William C. Colley III;
*/

     What's on this disk?  It goes like this:

	READ.ME		This notice.

	A68.DOC		The manual for the 6801 cross-assembler.  This file
			can be printed with the following command line under
			CP/M-80:

				A>pip lst:=a68.doc[t8]

	A68.H		The source files for the 6801 cross-assembler.  The
	A68.C		file A68.H also contains compile, assemble, and link
	A68EVAL.C	instructions for all compilers that I have used with
	A68UTIL.C	the package or that users have told me how to use with
			the package.

	TEST68.ASM	The entire instruction set of the 6801 CPU to use in
			testing the 6801 cross-assembler.

	A18.DOC		The manual for the 1805A cross-assembler.  This file
			can be printed with the following command line under
			CP/M-80:

				A>pip lst:=a18.doc[t8]

	A18.H		The source files for the 1805A cross-assembler.  The
	A18.C		file A18.H also contains compile, assemble, and link
	A18EVAL.C	instructions for all compilers that I have used with
	A18UTIL.C	the package or that users have told me how to use with
			the package.

	TEST18.ASM	The entire instruction set of the 1805A processor to
			use in testing the 1805A cross-assembler.

	A685.DOC	The manual for the 6805 cross-assembler.  This file
			can be printed with the following command line under
			CP/M-80:

				A>pip lst:=a685.doc[t8]

	A685.H		The source files for the 6805 cross-assembler.  The
	A685.C		file A685.H also contains compile, assemble, and link
	A685EVAL.C	instructions for all compilers that I have used with
	A685UTIL.C	the package or that users have told me how to use with
			the package.

	TEST685.ASM	The entire instruction set of the 6805 processor to
			use in testing the 6805 cross-assembler.

	HEXTOS.C	A conversion utility to convert Intel hex object files
			to Motorola S-record object files.  The program's
			documentation is at the top of its source file.

     I not only wrote these pieces of software originally and rewrote them in
"portable" C for all of you UNIX and IBM-PC users out there, but I am also the
librarian for the disk, and as such, I am responsible for maintaining the
packages.  I can only do this with YOUR help.  During the re-write, I noticed a
few bugs in the BDS C versions.  These were never reported to me by any of you
users, so I never knew to fix them.  PLEASE report bugs to me promptly so that
I can get them fixed.  I am only a letter or a phone call away.

     The lists of compile, assemble, and link instructions for the packages are
limited by my personal experience if YOU do not contribute.  In particular, I
have no access to a real UNIX system nor to an IBM-PC of any kind with any of
its dozen or so C compilers.  I need YOU to tell me how to use the package with
these systems and others.

     Once the first cross-assembler (the 6801 package) is written, adapting it
to other 8-bit or 4-bit processors (like the 1805A) is easy.  In fact, I once
adapted one of the BDS C versions to a 12-bit processor (the PIC1650).  It only
takes a couple of evenings for me to do it. What processors should be next, if
any?  Get your votes in, either to me or to the Users' Group.  Otherwise, the
selection of cross-assemblers will reflect only my needs, not yours.

     Having the author double as the librarian allows this disk to be a living,
growing entity, but its growth will be stunted by my lack of resources if YOU
do not contribute your share.  Speak up, for everybody's sake!

						William C. Colley, III