AMD: Windows-8-on-ARM app compatibility is relative

The matter of whether existing Windows applications will run on Windows 8 on ARM – putting them on tablets – has been kicked back and forth a lot this year.

Intel this spring pointed out that Windows applications running on x86 for PCs won't run on Windows 8 on ARM. Intel senior vice president Renée James, speaking at an investor event, said that Microsoft is planning four Windows versions for ARM systems and said these would not be backwards compatible and would only run on their specific Systems-on-a-Chip architecture.

This prompted Redmond to fire back with a statement calling James' claims "factually inaccurate and unfortunately misleading". It didn't say which part of James' comments were inaccurate and misleading, however.

For its part, Microsoft has hedged on the subject of application portability. The executive running the Windows 8 roadshow kicked off 2011 by also pointing out x86 programs don't run on ARM – but went on to say that compatibility won't be a major barrier in Windows 8, with Microsoft already getting a native version of Word running on ARM.

Now AMD has climbed into the debate. Intel's chip competitor has suggested compatibility won't be an all-or-nothing deal, and it will instead depend on the kind of applications you are building and running.

AMD, one of Microsoft's biggest partners putting Windows on x86, has told us that applications running on Windows today would have to be recompiled for ARM.

AMD's chips are compatible with Windows 8, AMD senior manager for client software marketing Gabe Gravning told us ahead of Microsoft's Build conference next week. Gravning added that AMD chips will support the classic Windows 8 desktop and the tiled Metro user interface so far only seen on Windows Mobile phones. Based in AMD's offices in Washington State, the home state of Microsoft, Gravning says he works closely with Redmond.

"We know that applications running on Windows today will have to be recompiled for ARM," Gravning said.

However, it sounds as if this will apply to native applications – written for existing x86 – and ISVs will be have the option of different layers that they can write their apps to.

"There will be some stuff that's compatible between the architectures and there will be completely new applications written for the new API and native languages which are going to have to be ported," Gravning said.

Gravning didn't go into more technical detail but instead said Microsoft would talk more about its application model for Windows 8 at the Build conference. Microsoft is also expected to release the first Windows 8 beta at the Anaheim, California conference. ®