GameBoy emulator in progress
https://www.pastraiser.com/cpu/gameboy/gameboy_opcodes.html
https://gekkio.fi/files/gb-docs/gbctr.pdf
http://marc.rawer.de/Gameboy/Docs/GBCPUman.pdf
https://files.nekoblog.org/uploads/pdf/39999184-GameBoy-Programming-Manual.pdf
https://github.com/mvdnes/rboy