6800: http://www.8bit-era.cz/6800.html
6502: http://www.6502.org/tutorials/6502opcodes.html#JSR
PDP-11: https://programmer209.wordpress.com/2011/08/03/the-pdp-11-as...
Motorola 68000: https://mrjester.hapisan.com/04_MC68/Sect05Part05/Index.html