" i dont know how anyone gets paid to do this and yet there is so much incredible depth to learn that is probably undocumented because of legal issues" - There

" i dont know how anyone gets paid to do this and yet there is so much incredible depth to learn that is probably undocumented because of legal issues" - There IS a path to commercial emulator development. Most of these "retro collections" you see being sold on video game online shops are a frontend, a custom made emulator to avoid any legal/license issue (Avoiding GPL code as much as possible), a cool frontend and some extras depending on how much the team could unearth and license from the original developer/publisher/rights owner. Hell, Nintendo and Sony had teams making official emulators for the Playstation 1 emulation on PSP/PSVita/PS3 or almost every nintendo console before the GameCube for Virtual Console games - Each country has its own set of laws, but using US cases as an example, developing an emulator for research purposes only (or at lease not competing directly with whatever you're emulating) and not using any file or code snippet from the original hardware can get a pass. That's how some emulators go by without getting a Cease and Desist from Nintendo or Sony. And that's why they never bundle the BIOS with the emulator, even if it needs it to emulate... well... Basic Input and Output Systems.