Apps written for x86 Windows PCs won't be able to run on ARM-based Win 8 tablets, according to a Microsoft exec who says his earlier statements about cross-platform compatibility were misinterpreted.
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In a clarification, a Microsoft executive said x86 applications built to run on the desktop version of Windows 8 won't be compatible with the tablet version of the operating system. The executive also said that the tablet version won't be able run any applications built for previous versions of Windows.
"We've been very clear since the very first CES demos and forward that the ARM product won't run any x86 applications," said Stephen Sinofsky, president of Microsoft Windows unit, during a meeting with financial analysts Wednesday. Windows 8 for tablets runs on devices powered by chips designed by U.K.-based ARM. The desktop version runs on traditional, x86 chips from Intel and AMD.
Sinofsky's comments came a day after he implied that apps for the tablet and desktop versions of Windows 8 would be cross-compatible. "The demos we are showing you today are equally at home on ARM or x86," Sinofsky said, during a keynote presentation at Microsoft's BUILD conference in Anaheim, Calif.
A Microsoft spokesperson said Sinofsky was referring only to so-called Metro apps--touch-based applications that are designed for tablets but which also will run on Windows PCs.
At the meeting with analysts, Sinofsky said cross-compatibility of x86 apps would not be practical because apps need to be optimized to take full advantage of the hardware on which they're intended to run.
"The challenge is very interesting. If we allow the world of x86 application support like that, or based on what we call desktop apps in our start yesterday, then there are real challenges in some of the value proposition for [ARM] System on a Chip," Sinofsky said. "Will battery life be as good, for example? Those applications aren't written to be really great in the face of limited battery constraints, which is a value proposition of the Metro-style apps."
Windows 8 borrows the Metro interface from Windows Phone 7. Metro features interactive blocks called Live Tiles, which contain live data feeds from email, social networks, instant messaging, and other services.
Despite Sinofsky's insistence that Microsoft has been upfront for months about whether Windows 8 for tablets would support desktop apps, the fact is that the company has been tight-lipped and at times contradictory on the issue. Redmond partner Intel was actually the first to raise the question. Intel senior VP Renee James told attendees at the Intel Developer Forum in May that Windows 8 on ARM would not support x86 apps. "On ARM, there'll be the new experience, which is very specifically around the mobile experience, specifically around tablet and some limited clamshell, with no legacy OS," said James.
"Our competitors will not be running legacy applications. Not now, not ever," said James, referring to rival chip manufacturers that use ARM's SoC design. At the time, Microsoft called James' statements "factually inaccurate and misleading." The brouhaha between Redmond and its partner led to Intel yanking a transcript of James' remarks from its Web site. Now it appears Microsoft's most senior Windows executive has confirmed her statements.
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