Over the years, the video game Doom has become a sort of litmus test for proving new hardware. These days, just about every device on the market with a processor can run it — Doom doesn’t actually require many resources. But that wasn’t always the case, and older computers and video game consoles simply weren’t powerful enough to run it. That is true of the original Nintendo Entertainment System, which had just a fraction of the power necessary to meet Doom’s minimum requirements. Despite that, YouTuber TheRasteri has managed to get Doom running smoothly on a completely unmodified NES.
As TheRasteri points out, Doom requires 8MB of RAM and a 33MHz processor to run. The NES has just 2KB of RAM and a 1.79MHz processor. That should mean that it’s impossible to run Doom on the NES without modifying either the game or the console. But TheRasteri didn’t do either of those things. This is the full version of Doom, and the cartridge will work on any stock US-spec NES console. Instead, TheRasteri was able to accomplish this feat by cramming a Raspberry Pi inside of an NES cartridge. The Raspberry Pi is actually running Doom, and is more than powerful enough to run it smoothly.
That may seem like a bit of a cheat, but there is precedent for this technique. 1993’s Star Fox for the SNES famously used a similar method. The three-dimensional graphics used in Star Fox were groundbreaking for a video game console at the time, and Nintendo was only able to make that work because the Star Fox cartridge had a Super FX chip inside that provided 3D graphics acceleration. TheRasteri is using the Raspberry Pi in a similar way. Doom is running completely on the Raspberry Pi, and is just injecting the graphics into the NES. The NES, in turn, is sending control commands back to the Raspberry Pi. In a future video, TheRasteri will explain exactly how they made that work, so be sure to subscribe to their channel.