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WOA! Windows 8 on ARM Revealed

This week, after over a year of silence in the face of persistent and understandable questions from customers, tech enthusiasts and the press, Microsoft finally revealed more about its plans for Windows 8 on ARM or, as the company now calls it, WOA. I'm grateful that Microsoft answered a ton of questions about this release. There are, however, a few more questions too.

The WOA revelations come courtesy of a compulsively long blog post on Microsoft's official mouthpiece for Windows 8 information, the Building Windows 8 Blog. Hopefully, that team's code is a lot tighter than its writing, but regardless here's the pertinent info in about 20 percent of the space, along with some additional commentary.

As a backgrounder, Microsoft announced its intention to port the client version of Windows 8 to the ARMf architecture in January 2011, about 13 months ago. At the time, the company noted that it would make Windows 8 versions for "System on a Chip" (SoC) architectures from both the x86 (Intel/AMD) and ARM (NVIDIA, Qualcomm, and TI) worlds, and that both would support the majority of Windows 8 technologies and be largely compatible. The company showed off a special version of Office 2010 running on prototype ARM hardware, but did not promise to release Office for ARM systems. Instead, this was "a demonstration of the potential of Windows platform capabilities on ARM architecture."

The company also said that current generation Windows applications (i.e. those that run on Win32/Explorer) would not be compatible with WOA systems, and that all Metro-style Windows 8 apps would run identically on both x86 and ARM.

Since that preview, there have been a lot of questions about ARM-based versions of Windows 8. Just a few of the key questions include whether WOA systems would include the legacy Windows 8 desktop or just the new touch-centric Windows Runtime (WinRT) and Metro-style Start environment, whether Office would be ported in some way to the new platform (and if so whether it would be "full" Office or a Metro-based subset), and whether developers would be able to port today's x86-based Windows applications and utilities to WOA.

Those questions are now all answered. And thanks to the aforementioned blog post, I can now provide the following summary of WOA features and differences between this system and the more traditional x86-based Windows 8 PCs and devices we'll also see later this year.

It's all in the family. WOA, like the Windows x86 client, Windows Server, Windows Embedded, and Windows Phone, is a full-fledged member of the Windows 8 family. And this is true from two perspectives, technically and conceptually. Technically, WOA shares a lot of the underlying code from the x86 versions of Windows, though it will also require a high degree of tweaking because today's Windows versions contain tons of platform-specific code, and because individual ARM devices require, in effect, discrete and unique OS versions. (More on that below.)

Conceptually, using a WOA device will be just like using an x86-based Windows 8 device, for the most part: It will feature the same Metro-style Start screen and run the same Metro-style apps, it will feature the legacy Windows desktop (albeit a limited version; again, see below), and it will be compatible with the same basic set of peripherals. These two aspects, together, explain Microsoft's insistence that Windows 8 will provide a "no compromises" experience, regardless of the architecture.

Microsoft isn't forgetting Intel and AMD. While we've been waiting patiently for news--any news--about WOA, and Microsoft has finally delivered that, the company also wanted to ensure users (and, no doubt, it's partners) that it has also engaged in "a deeper level of collaboration with Intel and AMD on the full breadth of PC offerings than in any past release." So much of the work Microsoft has done to make Windows 8 work well on more efficient and portable devices applies to x86-based PCs and devices as much as it does to WOA devices.

App compatibility. All Metro-style apps, including those that are bundled with the OS and those that the user downloads or purchases from the Windows Store, will run on both WOA and traditional Windows 8 devices. Without getting into the technical details, the short version is that developers only need to write their code once and Visual Studio 11 will compile it automatically for both platforms. When a user does purchase a Windows 8 app, they can install it on up to 5 Windows 8 devices. These can include any mix of WOA and x86-based machines.

Application (in)compatibility. Third party Win32/Explorer style applications--that is, all applications sold and made today, will not work on WOA systems. They cannot be ported to WOA, and cannot be made available in any way to WOA users. In WOA, Microsoft is only providing the basic desktop features from Windows 8 (file management, task manager and so on), the desktop version of Internet Explorer 10, and special versions of key Office 15 applications (see below).

Furthermore, WOA systems will not support running x86-based applications in emulation or virtualization (and Hyper-V is not part of the WOA versions of Windows 8). Get the message? Only a tiny subset of desktop applications will work on WOA, and all of those will ship with WOA systems, from Microsoft only.

Developer support. Speaking of apps (Metro) and applications (legacy), developers will of course use the same tools (Visual Studio 11), languages (C, C++, C#, Visual Basic, or JavaScript), markup (HTML 5/CSS, XAML), and other technologies (DirectX) to create Metro-style apps that run in the Windows Runtime (WinRT) on both WOA and x86-based Windows 8 devices.

Interestingly, developers can in fact ship Win32-style code that targets ARM, but only as supporting code for native WinRT/Metro apps. As with the desktop, described below, this is in doubt only because WinRT today simply doesn't offer the full breadth of capabilities as does Microsoft's legacy APIs and frameworks. So this "old fashioned" code can be used, yes, but only in a supporting role. (Remember: The only way to ship Metro-style apps for Windows 8/WOA outside of a managed corporate environment is via the Windows Store.)

WOA devices will ship concurrently with Windows 8 PCs. Contrary to a persistent rumor, Microsoft intends for its ARM partners to ship WOA devices to market at exactly the same time as traditional, x86-based PCs and devices. This is expected to start in Q4 2012, though Microsoft has only said on record that Windows 8 will ship "this year."

WOA devices will be integrated, end-to-end products. With traditional x86-based Windows versions, Microsoft creates a single OS that runs on any PC. This is not the case with WOA, and I'm curious to see how well Microsoft handles supporting both types of systems.

With WOA, each device is in effect a unique environment, with a custom version of the OS, unique hardware devices and drivers, and firmware, and so on. WOA software will not be sold at retail as is the case with traditional Windows versions. Instead, a custom WOA version will come with each WOA device only. Microsoft's job, basically, is to ensure that these unique WOA versions operate and perform as identically as possible to each other and to x86-based Windows 8 versions. I'm not convinced this is possible, and I think we're going to see some winners and losers when it comes to WOA devices.

Coupled with this is the fact that each, unique WOA device is in fact a joint development project that involves not just Microsoft, but also the ARM chipset maker (NVIDIA, Qualcomm, or TI) and the device maker (TBD, but there will be several, at least, I'm sure). This is a whole new level of collaboration, and there are bound to be hiccups.

Updating. WOA-based systems will be updated through the traditional Microsoft mechanisms, which in Windows 8 include both Windows Update (drivers, OS updates) and the Windows Store (app updates).

Office 15 is included. Microsoft is including desktop versions of four Office "15" applications with WOA-based systems. These apps, Word, Excel, PowerPoint, and OneNote, are desktop applications, not Metro-style apps, but they will be specially made to be a bit more usable on touch-based WOA systems and will be power management friendly.

WOA includes a limited version of the Windows desktop. A few months back, my sources told me that WOA devices would not include the Windows desktop, the implication being that these systems would offer only the new, Metro-style Start screen environment. But Microsoft announced that WOA would indeed include the desktop. What gives?

Turns out that's a bit of subterfuge on Microsoft's part, and the desktop is only being included to the extent that it's still required. So while I'm not ready to vindicate my previous statement about the desktop, suffice to say it's transitional in WOA and will likely be gone completely in the next version. In WOA, the desktop is there for a handful of basic tasks only. These include file management with Explorer, task management with Task Manager, full-featured web browsing with IE 10, interacting with legacy peripherals, and to run those Office 15 applications, which are indeed classic desktop applications but make some concessions to touch interfaces with large tap targets on the ribbon and elsewhere in the UI.

WOA and Windows 8 are indeed dual-interface systems. WOA, like the Windows 8 OS on which it is based, does indeed present two completely different user interfaces and operating environments, the Metro-style Start screen and the desktop. And while I feel that Microsoft is naturally progressing toward a Metro-only future, the company says that's not necessarily so, and that users will need to deal with both environments for at least the time being.

"Some have suggested we might remove the desktop from WOA in an effort to be pure, to break from the past, or to be more simplistic or expeditious," the post reads. "To us, giving up something useful that has little cost to customers was a compromise that we didn’t want to see in the evolution of PCs. The presence of different models is part of every platform. Whether it is to support a transition to a future programming model (such as including a virtualization or emulation solution if feasible), to support different programming models on one platform (native and web-based applications when both are popular), or to support different ways of working (command shell or GUI for different scenarios), the presence of multiple models represents a flexible solution that provides a true no-compromise experience on any platform."

My gut feeling is that WOA users and those running x86-based tablets will find themselves in the Metro environment most frequently, while those on laptops and desktop PCs will be using the desktop more often. Whether this works out as expected and/or changes over time is something I'll be following closely.

WOA is not included in the Consumer Preview. While Microsoft intends to deliver its Consumer Preview milestone of Windows 8 on February 29, WOA will not be included in this release. Instead, Microsoft intends to provide "a limited number of test PCs to developers and hardware partners in a closed, invitation-only program" later in the year.

WOA is for mobile devices. While we could possibly see thin and light WOA-based desktops, WOA is really aimed solely at the mobile market, and the majority of the WOA devices we'll see will be slate-style tablets. With Microsoft bringing Windows Phone, WOA, and Windows 8 into the same stable, so to speak, we're starting to see an interesting blend of features that were previously only available on smart phones and similar devices make their way to more mainstream Windows devices. These include things like sensors (accelerometers, ambient light, and so on) and even software services like Exchange ActiveSync (EAS): Microsoft notes in its WOA post that the WOA/Windows 8 Mail app synchronizes via EAS; this is the first implementation of EAS on an OS that will run on a desktop PC that I'm aware of.

WOA devices do not sleep or hibernate. Like the appliances on which they're based, WOA devices do not feature complex power management choices, which means that you won't see options for Sleep or Hibernate. Instead, these devices work purely in the new Connected Standby power mode, like a smart phone. "When the screen is on, you have access to the full power and capabilities of the WOA PC," The B8 post reads. "When the screen goes dark (by pressing the power button or timer), the PC enters a new, very low-power mode that enables the battery to last for weeks ... the system dynamically adjusts power consumption and is always on the lookout for opportunities to reduce power to unused parts of the system."

By the way, Connected Standby will also be available on x86-based Windows devices, but importantly only on those based on an SoC architecture (i.e. tablets and slates, for the most part).

Questions remain

I mentioned up front that the recent WOA revelations, while very much appreciated, have of course opened up the door to a new wave of questions. Key among these are whether users should purchase a WOA device or x86-based PC or device, depending on their needs. Will there be WOA orphans over time as hardware makers introduce slowly selling devices and then abandon them, and if so, who supports them going forward? How can Microsoft claim that Windows 8 is a "no compromises" OS when literally no existing Windows software will even run on new WOA-based devices? How will these devices and Windows 8/WOA versions be marketed and differentiated? Will there be a version of Outlook for WOA? Or other Office applications? 

And so on, but you get the idea. WOA looks like a compelling and strong entry to me, but it's not without its compromises, and advising potential customers on which to consider is, for now at least, not possible. We live in interesting times, though, and I wouldn't have it any other way: I'm excited and uncertain about WOA and Windows 8. And that alone is actually pretty thrilling.

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