A programmer who goes by "Tom 7" found a way to make Super Mario World for the SNES run on an unaltered 8-bit NES. This clinches it. If artificial intelligence ever gains sentience and puts humankind on trial for its perverse experiments on technology, there's going to be a not-small chunk of time dedicated to our love for pushing hardware far, far beyond its means.
Thankfully, we're still in the era of dumb and complacent machines, so let's just revel in what Tom 7's done. He's no stranger to getting weird with tech: His YouTube channel is full of odd projects and dissections. But Tom 7's reverse emulation of the NES hardware is a real interesting chimera, and he's only too happy to explain how he got Super Mario World running on the grey lady. It's a lengthy video filled with technical jargon, so if you're not into any of that (though Tom 7 makes it as digestible as possible with a "Nintendo Power Point presentation"), skip to 16:10. Beautiful, isn't it?
While Tom's methods involve using a cartridge with a Raspberry Pi installed on it, the NES hardware isn't altered at all. Even the NES controller is used in the demonstration, which means Mario can only jump with "A" (which executes his spin jump). Incidentally, when I first played the SNES as a kid, I hesitated to make Mario jump with "B." It seemed … wrong.
Want to get into the real nitty-gritty on how Tom 7 reverse-emulated the NES? He's got a very in-depth video for that purpose.