Will Windows 8 run x86 apps on ARM tablets -- or not?

Microsoft has done a poor job of telling developers exactly how the ARM and Intel implementations of Windows 8 differ

The Web today is abuzz with all sorts of conflicting stories about running "legacy" Windows 7 apps on the ARM Windows 8 desktop. Microsoft hasn't given a simple yes-or-no answer to this vexing question, but I thought Galen Gruman nailed it several days ago, in his post "Windows 8 on ARM chips: It was too good to be true." He says that ARM-based Windows 8 machines won't run X86 apps, referencing Steve Sinofsky's response during the earnings call last Wednesday.

Here's what Sinofsky said: "We've been very clear since the very first CES demos and forward that the ARM product won't run any X86 applications. We've done a bunch of work to enable that -- enable a great experience there, particularly around devices and device drivers... [W]hat we announced yesterday for the first time was that when you write a Metro style application, all the tools are there to enable you in any of the languages that we support to automatically support ARM or X86. I think that's the key part of everything that we'll run."

That makes it pretty clear to me that traditional X86 apps won't run on ARM Windows 8 machines, although developers may be able to write similar apps for both ARM and Intel hardware -- providing they're writing for the Metro interface.

There's no question that Windows 8 on ARM will support the same bifurcated interface we saw on the prototype Samsung Intel tablets distributed the Build conference. Website Thisismynext ran a series of photos of ARM Windows 8 machines, taken at Build. Both the tiled Metro interface and the traditional Windows Desktop interface appear on all of the ARM machines. Several shots show the Desktop interface, with taskbar, a Recycle Bin, and running the Windows Task Manager -- shots that look exactly the same as the Windows 8 Developer Preview running on a standard Intel desktop.

There's also no question that current Windows 7 apps will run, unchanged, on the Desktop interface in Windows 8 on Intel machines. (At least, they're supposed to.) I've been working with a raft of apps, including Office 2010, that run just fine in the Desktop interface on my Windows 8 Intel machine.

Some people, though, are claiming that traditional X86 programs will run on ARM Windows 8 machines with a simple re-compile. I can find no Microsoft documentation -- not even a whisper -- to substantiate that claim. Quite the contrary.

I guess the most exasperating part of the controversy is simply that it exists at all. Clearly Microsoft has done a poor job of telling developers exactly how the ARM and Intel implementations of Windows 8 differ. We've seen a lot of information about building Metro interface vs Desktop interface apps. We've seen -- indeed, more than a million people right now are running -- Windows 8 on Intel hardware. People are kicking the tires with the Metro interface. But only on Intel hardware: the ARM flavor remains a great unknown.

It's a crucial question, not only for developers but also for people who follow Intel's fortunes. If Microsoft kicks traditional Windows desktop apps off ARM devices, and ARM architectures continue their meteoric rise, Intel may find itself sitting in a dwindling desktop pool. It would certainly change the market dynamics for thousands of software companies -- and untold legions of corporate developers.

I guess we'll have to wait and see.

This story, "Will Windows 8 run x86 apps on ARM tablets -- or not?," was originally published at InfoWorld.com. Get the first word on what the important tech news really means with the InfoWorld Tech Watch blog. For the latest developments in business technology news, follow InfoWorld.com on Twitter.

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