Platinum’s Kamiya Demands Nintendo Switch Virtual Console And Regular D-Pad Joy-Cons

Nah, emulators are software that well.. emulate the original hardware. It’s difficult to explain what an emulator does briefly but I’ll try.

Okay so, as an example, the NES has 8-bit Ricoh CPU which has an architecture and instructions that would be completely alien to the ARM chip in the Switch, so the emulate has to go through some steps to figure out what those Ricoh instructions are supposed to do.

1. First has to do is run some code that mimic the way the original CPU read those instructions from memory AKA it’s command process.
2. It needs to run some code to determine what Ricoh instruction it is. It might do that by looking up a list of possible instructions that are stored in memory.
3. When it finds which instruction it is, it then knows the length and structure of the data it can expect to be fed into that instruction and retrieves it.
4. It then uses that data and plugs it into some ARM code that mimics that Ricoh instruction so that it get’s the same result.

However, it’s almost never a matter of just doing the ARM equivalent of that instruction though. Just based off the fact that Switch’s processor is 64-bit and the Ricoh processor is 8-bit, it’ll at least need to limit the precision of certain math. For example, lets say an 8-bit CPU can only add with 8-bits of precision. That would limit it’s largest sum to 255 (0-255 being the only range of numbers that be represented in 8-bits). By comparison, the largest 64-bit number is over 18 quintillion. Needless to say, you’d need to make sure that the emulate limits emulated CPU’s highest number to 255. But it’s not just that, you need to determine how the original CPU handles adding an number, lets say 1, to 255. Does it just stay at 255 or does it “overflow” and become 0 again?

It does that very every single instruction, for every single processor. While making sure to mimic the same clock speeds and latencies so while trying to keep those emulated processors in sync.

If the emulator is accurate enough, you should be able to feed it any ROM and have it run exactly as it did on the original hardware. Any improvements come from any areas where hardware doesn’t have to emulated completely accurately or where things can be bullshitted. For sprite-based consoles, then can get away with scaling the final frame better than a TV could which leads to a less blurred picture. And with pretty much every console you can usually get away with faking controller input. That’s why so many emulators can do networked multiplayer, its just a matter of accepting input commands over a network before it’s fed into the emulator… though you also need to keep both copies of the game in sync.

Anyway, hope that helps. Hopefully, I didn’t put you to sleep lol