So the Arm revolution on the Pc is almost here, probably the first Windows laptop to pack the radical new Qualcomm Snapdragon X Elite chip, which arrived on 6/18. But if there's a big question mark hanging over the entire endeavour, it's emulation. More specifically, is X Elite good for running old x86Windows code?

That means most of the existing software and apps for Windows, because Windows is overwhelmingly an OS running on x86Cpu. We know that some key apps, such as Chrome Browser and Adobe Photoshop, will be available in native Arm format for x Elite laptops from day one. But what about everything else.

This should all run in emulation mode courtesy of a new translation layer known as "Prism" in the upcoming update for windows11 24H2 Prism will convert code from X86 to Arm on the fly. This is not a new concept, in fact Windows For Arm has been supporting x86 emulation for years. It just wasn't very good. By contrast, Apple's Rosetta2 emulation layer for Apple silicon Mac is pretty impressive. Of course, Apple silicon is Arm-based and has replaced the Mac of the Intel X86 era. So you have to compare directly between Microsoft's Prism and Apple's Rosetta2.

Just for context, the original Rosetta translation layer helped smooth Apple's previous transition in 2006 from PowerPC Cpus to Intel x86. Of course, "Rosetta" is an ancient tablet engraved with 3 versions of the same text, written in Greek, demotic and Egyptian hieroglyphs, named after the Rosetta Stone, which has become the key to deciphering demotic scripts and ancient hieroglyphs.

In any case, Microsoft has made some bullish claims against Prism, but most of them are either a bit vague or difficult to fully measure. For example, according to Ars Technica, Microsoft thinks Prism will do what Rosetta did on the Mac with an Arm Pc, and Prism's performance and efficiency are similar to Rosetta's.

Microsoft specifically states that "the powerful new Prism emulation engine improves performance 9x compared to the Surface PRO5W/2g," but that's in both hardware and improved emulation. Microsoft also claims that Prism runs code 10-20% faster on existing Arm chips than previous emulation layers, so older Windows Arm devices like Surface Pro9

of course, both performance and efficiency are important. Emulated software is notoriously bad for battery life, so power efficient transcoding will be a big advantage.

But perhaps the most important element of all these is the repeat with the Windows11 and Prism itself's 24H2 update being specifically optimized for the X Elite chip, while Apple's comparison is evident here.

Apple's Arm-based chips have hardware features and optimizations designed to improve x86 emulation. For example, the way Arm and x86 order memory is based on different models known as weak and strong, respectively. Both models are built into Apple silicon, so there is a big difference in performance and efficiency.

What is not known and very interesting to find is whether Snapdragon X Elite has similar hardware features to support x86 emulation, except for the fact that it would benefit, the main reason we think it could be is that the CPU core of the X Elite is the same as the CPU core that Qualcomm acquired in 2021.

But here is the real kicker. Before co-founding Nuvia in 2019, its CEO, Gerard Williams, was Apple's chief CPU architect for almost 10 years. The company was staffed by other former Apple engineers involved in the company's tranistion to Arm. It's safe to say Nuvia, so Qualcomm knows all about the special source of Apple silicon that performs emulation very well.

How good the X Elite is has not yet been proven. Qualcomm had previously claimed that even the game "works well" with the X Elite, but recently found that the MacBook AIr is surprisingly good for the game in a few narrow scenarios. But there is a lot to be proven. And Microsoft's track record in this area is not exactly stellar, as Qualcomm's big problem relies on Microsoft to do the job properly, whereas Apple has complete control over the entire hardware and software stack.

What we can say for sure is that emulation performance will be the key to X Elite's success and the prospect of the Arm chip in the PC.