In celebration of the 50th birthday of the 6502 I cleaned up and repaired the Atari BASIC Source Code based on the original "Atari BASIC Source Book" by Bill Wilkinson, Kathleen O'Brien, and Paul Laughton. I started with a very good cleaned up dump Atari BASIC Rev.A/B/C from AtariAge that builds with ca65 and made the following improvements:
- BNF Macros: BNF elements are now neatly defined inline with
.byte. Much easier to modify and extend. - Added
sourcebook.incheader with aliases for older / original symbol names for better alignment with the Source Book. - Applied original comments throughout the code — including almost all original typos!
- Applied uppercase to all the Rev.1 mnemonics, leaving Rev.2/3 lowercase and un-documented.
- Simplified the
Makefileand added SHA1 validation of the standard builds.
Enhancements for Atari XL/XE versions of BASIC have not been applied as of this writing.
This language can be improved by a mile. To modify the language you should add new BASIC_REVISION conditionals, then modify the link size and headers as-needed to get it to build and run. The Makefile is set up to build the historical cartridge ROMs, but it shouldn't be too hard to make runnable XEX files.
Watch this space as I'm working on implementing an AtariBASIC tokenizer (and runner?) in Python and Javascript. This source code is going to be a very helpful guide in that project.