Beware: Xbox One Backwards Compatibility Hack Is A Hoax, Could Brick Your Console

There's a rumor going around on social media that you can enable Xbox 360 backwards compatibility  on an Xbox One by hopping through a series of steps meant to enable Developer Mode, changing a setting, and restarting the box. Don't believe it. There is no method of allowing the Xbox One to play Xbox 360 games, via any software program. Microsoft's Major Nelson has denounced the idea directly.

This is an opportunity to talk a bit about <em>why</em> you can't play Xbox 360 games on the Xbox One, and how we know the entire program is a hoax.

The Backwards Compatibility Conundrum

There are two ways to make a system backwards compatible. The simplest is to build a complete version of the old console inside the new system. Sony's first generation of PS3's, for example, actually had a full PS2 implemented in hardware. This is relatively easy -- by the time the new console launches, the old console is well understood and its processors are much smaller than they used to be. It takes some additional work to ensure local storage is shared and partitioned between the two devices, and that controllers are cross-generation compatible, but this is all workable. Problem is, it's also expensive. Both Sony and Microsoft chose to save money this generation, and we know neither the PS4 nor Xbox One contains previous generation hardware.

That leaves software emulation -- and software emulation is a decidedly mixed bag. Ars Technica did an excellent writeup on the problems facing perfect emulation several years ago, but here's the bottom line: Emulating 95% of a game's behavior is easy. Emulating that last 5% -- including edge cases that can break an entire game -- is extraordinarily difficult. Small errors can lead to audio issues, graphics corruption, or make it impossible to finish a title. Perfect emulation is extraordinarily expensive -- accurately duplicating the SNES in hardware requires a 3GHz x86 processor, where the original system had a 21.47MHz input frequency and a 3.55MHz bus.

Obviously there are emulators with far, far lower requirements -- but they're much less compatible with edge-case software. Microsoft would need to target a high level of compatibility to truly market the feature -- but emulating a modern multi-threaded Xbox 360 game on the Xbox One's eight Jaguar CPUs would be an exercise in futility. Eight Jaguar cores may outperform three dual-threaded Xbox 360 cores in aggregate, but Xenon was designed for high clock speeds. A game designed to run on a 3.2GHz chip is going to struggle on a core clocked at a little more than half that speed.

The reason there are no major emulator projects for PS3 or Xbox 360 hardware, despite their age, is that the architectures are too difficult for conventional PCs to model. With CPU performance improvements having slowed to a crawl, that's unlikely to change. Don't be fooled -- the only way to experience an Xbox 360 or PS3 title will be to buy the console itself.