Stuff from todo file

[tobiasvl]

6800 -> 6801/6803 (10 extra instructions)
6800 -> 6805 (ikke binary compatible)
6809 (prefix)

https://spivey.oriel.ox.ac.uk/wiki/images-corner/1/1a/Undoc6800.pdf

https://deramp.com/downloads/mfe_archive/050-Component%20Specifications/Motorola/CPUs/The%20Motorola%206800%20Instruction%20Set%20(Byte)(January%201978).pdf