Windows 8 On ARM Won't Run Old AppsWindows 8 On ARM Won't Run Old Apps

Windows 8 Upgrade Plans: Exclusive Research

Computer users who were hoping to run their existing apps on snappy new Windows 8 tablets that Microsoft and its partners are expected to release later this year are out of luck, at least when it comes to systems powered by ARM-based chips.

Windows chief Steven Sinofsky has confirmed that the version of Windows 8 that Microsoft is developing for ARM packages from Qualcomm, Nvidia, and Texas Instruments will only run new apps developed specifically for the SoC platform. And those apps will only be available as downloads from the official Windows Store, an online market that Microsoft plans to open about the same time Windows 8 officially launches.

"WOA [Windows on ARM] does not support running, emulating, or porting existing x86/64 desktop apps," said Sinofsky, in a blog post. "Consumers obtain all software, including device drivers, through the Windows Store and Microsoft Update or Windows Update."

[ Will Windows 8 be right for you? Read 8 Features That Could Make Windows 8 Great. ]

Sinofsky said the technical challenges in enabling legacy app support on WoA systems are only part of the reason why ARM-based tablets will only run new, Metro-style apps.

More significantly, he said Microsoft wants to build a closed-loop tablet ecosystem that offers users predictable, high-quality performance across a range of devices--something that's too difficult to guarantee in Microsoft's traditional, open ecosystem.

"Supporting various forms of emulation runs counter to the goal of delivering a product that takes a modern approach to system reliability and predictability--by definition, existing code has not been optimized for the platform the way WoA has," said Sinofsky.

"If we enabled the broad porting of existing code we would fail to deliver on our commitment to longer battery life, predictable performace, and especially a reliable experience over time. The conventions used by today's Windows apps do not necessarily provide this," he said.

The good news for users for whom running old Windows apps on new tablets is a priority is that Microsoft says it's committed to driving the development of tablets that will run a version of Windows 8 that is compatible with chips from Intel and AMD.

"If you need to run existing x86/64 software, then you will best be served with Windows 8 on x86/64," said Sinosfksy. "We could not be more supportive of the new products from Intel and AMD."

Intel is building out its Atom line of processors for tablets and smartphones, while AMD is targeting the mobile market with its Fusion architecture. Microsoft has yet to announce a release date for Windows 8, but many analysts believe the OS will ship in time for the 2012 holiday season.

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