A New Windows Insider Build Lets ARM PCs Emulate x64 Like Apple's Rosetta 2

Surface Pro X.
Surface Pro X.
Image: Microsoft

Yesterday, Microsoft announced it released the first preview of x64 emulation for ARM64 devices on Windows 10 to users enrolled in the Windows Insider Program. The new feature is a part of Build 21277 (RS_PRERELEASE), which also includes updates to emojis, redesigned touch keyboard, voice typing, and theme-aware splash screens, as well as fixes for a bunch of bugs.

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According to the announcement, Windows Insiders can install any x64 apps from the Microsoft Store or any other location, whether its streaming apps, games, or productivity programs. Users can even run a 64-bit version of internet browsers like Google Chrome, which can be a bit of a memory hog. Emulated as a 64-bit version instead of a 32-bit version allows the browser to access more computer memory, which should help performance.

Windows Insiders will need to install a preview version of the Qualcomm Adreno graphics driver for the Samsung Galaxy Book S, Lenovo Flex 5G, and Surface Pro X in order to get the 64-bit emulator working on their device. Additionally, users will need to install a preview version of the ARM64 C++ redistributable from here. Microsoft says Windows Insiders will only need to do this once, as those two steps will not be required for future Insider builds.

“When we first launched Windows 10 on ARM in late 2017, the long tail of apps customers needed were dominated by 32-bit-only x86 applications,” said Hari Pulapaka, Partner Group Program Manager of Windows. “Over time, the ecosystem has moved more toward 64-bit-only x64 apps...That’s why we are working on expanding the capability of our emulation to include x64 applications and sharing this first preview to gather feedback.”

Windows on ARM has only been able to emulate 32-bit apps programmed for x86 (Intel or AMD) processors, which is a bit of an issue because many software developers have stopped supporting 32-bit versions of their applications in recent years. Even Windows 10 stopped supporting 32-bit programs with the 2004 version of the OS. It all comes down to how much system DRAM 32 and 64-bit apps use.

While 32-bit programs can only access up to 4 GB of DRAM, 64-bit programs can access much, more than that—up to 128 GB for the home edition of Windows 10 and up to 2 TB on the Pro, Enterprise, and Education editions. Practically all PCs come with a minimum of 8 GB of memory these days—anything else is a sin against computers—so there’s not much reason to keep making 32-bit versions of applications anymore.

There are devices like the Surface Laptop Go, a very budget laptop that comes with only 4 GB of memory, that still exist, but even then 64-bit applications are still the better option because they support a much larger amount of DRAM. Makes sense to have one standard rather than two as far as modern laptops are concerned.

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It could be a while before x64 emulation for ARM64 leaves the Windows Insider program and rolls out to all Windows 10 users, but this is finally a step in the right direction and could gather more consumer interest for Windows Arm laptops—especially now that Apple has launched its new M1 Arm processor in a few of its products. Not too many native x86 applications have been ported to Arm yet, so it’ll be necessary for users to at least have access to an emulator if they want to make the switch to a different processor architecture. Apple already has Rosetta 2, which we’ll get the chance to test here soon enough. Microsoft needs to play catch up with emulation if it hopes to compete in the Arm-space, but it’s well on its way.

Staff Reporter, Reviews at Gizmodo. Formerly PC Gamer, Maximum PC.

DISCUSSION

How much of Microsoft’s delay was impacted by Intel being so vocal against Windows natively emulating x86 processors? It is quite possible this feature will find itself in the production version of Windows on ARM before this time next year.