x86 on ARM

Microsoft shows how Windows 10 on ARM legacy app emulation works

Microsoft builds a x86 emulator to allow legacy apps to run ARM-powered devices to prevent the headaches of Windows RT.

Windows 10 on ARM

Windows 10 on ARM is not Windows RT all over again, instead Microsoft is building a version of its OS that supports the full desktop experience with features you come to expect, including Cortana, Microsoft Edge, Ink, Windows Hello, and most importantly support for legacy apps.

The company explains this in a video published as part of the Build 2017 developer conference, where they also share details on how their x86 emulation technology works to support for traditional desktop (win32) applications.

The video also highlights that with Windows 10 on ARM is meant to address two specific consumer needs, including better battery life and an always connected experience using integrated LTE technologies.

Mobile devices running this version of Windows 10 will start hitting the market by the end of 2017, and they will sport Qualcomm Snapdragon processors.

In the video, the device Microsoft demos is running a x64 version of Windows 10 Pro on an 8-core Qualcomm Snapdragon 835 chip with 4GB of memory. Additionally, the company reveals that will also ship the OS with a large array of ARM-based class drivers to support modern peripherals.

How the x86 to ARM emulator works

While built-in apps will run without a glitch, the most interesting aspect of the ARM version of Windows 10 is how it runs apps (e.g., Photoshop, iTunes, Chrome) that have been designed for a different processor architecture (x86).

According to the software giant, the x86 win32 emulator makes everything transparent to end users, and everything works like on any desktop computer. The emulator runs on top of a WOW (Windows on Windows) layer, which is a similar infrastructure found on x64 systems to run x86 apps. Another key part of the process is CPU software emulator to translate x86 to ARM, which something traditionally (x86 to x64) runs on hardware, but this is not possible as the processor has a different architecture.

Although it’s expected that traditional desktop applications will run normally, the best experience will always be to run native Windows Store apps. Modern apps you download from the Store will not impact on the processor, memory, or battery as much as the emulated code.