Windows 8, Traditional Windows Apps, and ARM

Paul McDougall, InformationWeek:

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.

No one should be surprised that existing x86 binaries won’t run on Windows on ARM. That would require something like Rosetta, the on-the-fly emulation layer that allowed Intel-based Macs to run compiled-for-PowerPC apps.

The question is, though, will Windows developers be able to recompile existing apps for ARM? I’ve been looking for a definitive answer and I don’t think Microsoft has given one. This bit from Sinofsky suggests, though, that they will not:

“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.”

I’m feeling good about my prediction the other day that ARM-based Windows machines will be Metro-only. (I say “machines” rather than tablets because I think we’ll see Windows ARM notebooks too.)

★ Friday, 16 September 2011