Microsoft is fencing off a piece of Windows 8 called Windows on ARM (WOA) that is designed specifically for deployment on devices with low-power ARM processors - such as tablets and that has capabilities customized to that environment.
While the company has been talking about Window 8 support for ARM-based devices as well as x86 PCs, this is the first time it has set off those capabilities as a separate category.
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"WOA is a new member of the Windows family, much like Windows Server, Windows Embedded, or Windows Phone," says Steven Sinofsky, who heads up Windows 8 development and writes the Building Windows 8 blog.
"WOA builds on the foundation of Windows, has a very high degree of commonality and very significant shared code with Windows 8," he says.
In addition the company has collaborated extensively with chip makers AMD and Intel, moreso than in previous Windows OS development, Sinofsky says.
While Windows 8 has been touted as supporting both traditional PCs and those powered by ARM chips, WOA is just for ARM devices and will support only applications written in the Windows 8 Metro style, the blog says. They will require hardware being built by NVIDIA, Qualcomm, and Texas Instruments that should be ready about the same time the operating system is later this year.
That doesn't mean WOA doesn't support traditional Windows Office applications. Rather it will include desktop versions of Office 15 Word, Excel, PowerPoint and OneNote that have been redesigned to use less power and provide touchscreen support that WOA hardware feature. The apps will be compatible with documents produced on the corresponding non-Office 15 apps.
WOA will only be sold packaged with hardware.
These PCs will be based on system on a chip (SOC), essentially a miniature motherboard in function, designed by the partners Nvidia, Texas Instrument and Qualcomm.
WOA PCs built around these SOCs are never turned off. When the power button is pushed, the device goes into connected standby mode, which is so low power it can remain there for weeks before the battery drains. But it keeps applications alive so when full power is restored, they are available instantly.
These devices are sold with WOA software, and that is how they must remain, Sinofsky writes in his blog. " End-users are technically restricted from installing a different OS (or OS version) on a device or extending the OS, so this is generally not possible, and rarely supported by the device maker. Device makers work with ARM partners to create a device that is strictly paired with a specific set of software (and sometimes vice versa), and consumers purchase this complete package, which is then serviced and updated through a single pipeline," he says.
The company will give out a limited number of WOA test PCS when it releases Windows 8 Consumer Preview Feb. 29. "These devices will be running the same branch of Windows 8 on x86/64 as we release broadly at that time. These are not samples or hints of forthcoming PCs, but tools for hardware and software engineers running WOA-specific hardware," the blog says.