Docs
Amiga programming and source code
https://github.com/chrhhn/guidetoamigacompatibleprogramming
http://amiga-dev.wikidot.com/information:hardware
http://amigadev.elowar.com/read/ADCD_2.1/Hardware_Manual_guide/node0000.html
http://pasti.fxatari.com/68kdocs/68kPrefetch.html
http://zakalwe.fi/~shd/amiga-cracking/agafix-v1.html
https://wiki.amigaos.net/wiki/Main_Page
https://www.amigagamedev.com/
https://gitlab.com/amigasourcecodepreservation
Disassembly of some Amiga components
http://wandel.ca/homepage/execdis/
MS-DOS Programming
The art of assembly language
http://flint.cs.yale.edu/cs422/doc/art-of-asm/pdf/
Commodore 64 programming
http://www.classiccmp.org/cini/pdf/Commodore/C64%20Programmer%27s%20Reference%20Guide.pdf
http://www.zimmers.net/cbmpics/cbm/c64/c64prg.txt
General source code repositories
https://github.com/historicalsource?tab=repositories
Tools
Amiga tools
https://github.com/cnvogelg/amitools
https://github.com/adtools/amigaos-cross-toolchain