SDCC AS and LINK history
The mcs51 (asx8051, aslink), z80 (as-z80, link-z80), gbz80 (as-gbz80, link-gbz80) and hc08 (as-hc08, link-hc08) assemblers and linkers, which are part of SDCC source tree, are derived from ASXXXX, written by Alan Baldwin: mcs51 (asx8051, aslink) and hc08 (as-hc08, link-hc08) are derivates of version 1.70, z80 (as-z80, link-z80), gbz80 (as-gbz80, link-gbz80) are derivates of version 1.75.
This may also be interesting: http://plit.de/asem-51/home.htm
ASXXXX V 1.70 and V 1.75 were issued with the following statement in file ASXXXX/ASXDOC/ASMLNK.DOC:
The ASxxxx assemblers and the ASLINK relocating linker are placed in the Public Domain. Publication or distribution of these programs for non-commercial use is hereby granted with the stipulation that the copyright notice be included with all copies.
In ASXXXX V 4.00 the following End User License Agreement was added in files README.TXT, ASXV4PXX/README.TXT, ASXV4PXX/ZIPPER/README.TXT, ASXV4PXX/ASXDOC/ASMLNK.DOC and ASXV4PXX/ASXHTML/ASXHTML.HTML:
E N D U S E R L I C E N S E A G R E E M E N T This software is FREEWARE which means it is NOT public domain but fully copyrighted material that is distributed freely without money. Its electronic distribution through BBSs, the Internet, or other such means is encouraged provided no money is requested in return. It is forbidden to distribute this software should this file, or any of the remaining files, change in any way or be omitted from the archive. If you would like to include this software together with your own work you MUST include it only as the original complete un- modified archive in which I distribute it and not as independent files. If uncertain, simply point others or link to: http://shop-pdp.kent.edu/asxhtm/asxxxx.htm Please note that although I have done my best to ensure there is no potentially dangerous code (or accidental virus infec- tions), the nature of programming is such that it forces me to provide absolutely no warranty, express or implied, with this version of the software, and I bear no responsibility for what- ever damages, direct or consequential, you may suffer from its use. I definitely do not warrant this software for suitability for any particular purpose, either. It is also possible that the instructions, the extra utilities, or the examples that come with the software contain errors, none of which were inten- tional.
It is forbidden to distribute this software should this file,
or any of the remaining files, change in any way or be omitted
from the archive.
makes impossible to merge ASXXXX version V 4.00 or higher with the SDCC version, unless Alan Baldwin changes the license or makes an exception for use with SDCC :-(
NOTE: I wrote this only using the informations I found in SDCC svn repository and on ASXXXX home page. I didn't contact the ASXXXX author Alan Baldwin or Michael Hope [user:michaelh], who (at least what I can see from the svn history) added ASXXXX sources to the SDCC repository on 2000-01-17. My interpretation of the licensing can be wrong too.
History of the Z80/GBZ80 assembler
The z80/gbz80 assembler came from the pre-SDCC version of the Gameboy Development Kit (GBDK) which had been extended to the gbz80 by Pascal Felber. When I Michael started on SDCC I imported the assembler in as a separate fork to the existing mcs51 assembler. I looked at unifying the two assemblers and updating to a later version of ASXXXX at the same time but there proved to be too many changes in the forks and too much of a difference with the then-available 2.x version of ASXXXX.
To be continued
You can see continuation of the story at https://sourceforge.net/tracker/index.php?func=detail&aid=1896681&group_id=599&atid=350599