ARM-based Windows 8 systems won't run Windows 7 apps

Microsoft will not port legacy x86 Windows 7 applications to Windows 8 ARM devices

Microsoft will not port Windows 7 software to Windows 8 systems that run on ARM hardware.

Microsoft announced in January this year that Windows 8 will run on ARM processors, which currently power the vast majority of mobile phones, including Apple's iPad and mobile devices that run Google's Android operating system.

"We have a giant install base of x86 software, and that's a massive asset for the partnership between Intel and Microsoft, but it's not an asset we're going to port to ARM," said Microsoft president of the Windows and Windows Live division, Steven Sinofsky, speaking at the Microsoft BUILD conference taking place in Anaheim, California.

"Here's the reason," he said. "Those applications don't take advantage of all the things that make ARM a fairly neat offering right now."

Sinofsky took the example of power management and said that Win 32 apps don't take advantage of the power management used in ARM chips.

"Unless we can deliver the value proposition of that [ARM] hardware, there's no reason to port the software," said Sinofsky.

Users buying an ARM-based Windows 8 system who try to install their old Windows 7 applications will fail.

Asked how Microsoft would stop this scenario, Sinofsky said it would use "all our considerable communications resources to stop that happening".