Quote from: xlar54 on January 19, 2008, 09:42 PM6502:
http://www.6502.org/

6502 Instruction Set:
http://e-tradition.net/bytes/6502/6502_instruction_set.html

The link above lures me to page for downloading some, likely malware, software for Windows, but a good 6502 instruction set overview is here:

6502 Opcodes:
http://www.6502.org/tutorials/6502opcodes.html

Quote from: xlar54 on January 19, 2008, 09:42 PMSecond Book of Machine Language Programming:
http://www.atariarchives.org/2bml/index.php

Introduction to 6502 Assembly:
http://www.obelisk.demon.co.uk/6502/

C128 Assembly Programming
http://folkvagn.commodore64.org/c128assembly.htm

The above two links are dead. But the respective pages can be found on archive:

Introduction to 6502 Assembly (obelisk link):
https://web.archive.org/web/20150702230532/http://www.obelisk.demon.co.uk/6502/

C128 Assembly Programming (folkvagn link):
https://web.archive.org/web/20210823204733/http://commodore64.se/wiki/index.php/Commodore_128_assembly_programming