What Windows 8 on ARM means for tablets and desktops

Details have emerged about Windows 8 running on ARM-based tablets and PCs, but will Microsoft's Windows 8 tablet strategy succeed?

For a while now, people have been speculating how Windows 8 will run on ARM processors and what the implications are when it comes to tablets and ARM-based PCs. Microsoft recently released some details about Windows on ARM, and as Brian Madden pointed out in his analysis of WOA, it leads to even more questions.

A blog post by Microsoft's Steven Sinofsky gets into the gritty details of Windows on ARM (WOA), but those finer points (and their trailing questions) aside, I want to look at some of the broader statements in that post and evaluate what they mean to us in the desktop space.

We're starting to get an idea of what, exactly, Metro is all about.
Since the term Metro was introduced, a lot of people considered it a user interface change and not much more. As more details have emerged, it's clear that Metro apps aren't just about the user interface that replaces the desktop; it is an entire environment that runs alongside the traditional desktop. Metro has been designed to provide a hardware-agnostic development platform between x86/64 and ARM-based applications, and I believe it's key to Microsoft having any success at all with WOA.

Unfortunately, that means the Windows kernel now supports Metro and desktop apps on x86, 64-bit and ARM-based platforms, and I fear more fragmentation could result. Metro is the attempt to unify that, but until everyone starts developing for Metro apps, success is a long way away.

Only apps from the Windows Store will run in Metro on WOA. All Metro apps are WOA and x86/64 compatible.
Metro is critical because the application files will be universal across hardware platforms, much like how Apple has "universal" binaries for dealing with PowerPC and Intel platforms.

This is exactly what Microsoft needs to do to break into the ARM world. It's not the first time they've ported Windows to other platforms (you could run Windows NT on DEC Alpha, MIPS and PowerPC when it was first released), but those were all niche solutions. The applications weren't compatible because they were written for certain platforms, and while Microsoft tried to make some Microsoft-branded apps for them, the rest of the world pretty much ignored them.

ARM, on the other hand, isn't a niche. Almost all mobile devices run an ARM processor, but Windows has remained a non-factor in the ARM arena until now. Windows Phone 7 runs on an ARM-based processor, but that's not the same kernel, and the interface only looks like Metro (at least, that's my understanding). So, the fact that all apps that run in Metro will run on all platforms in Windows 8 is incredibly important for Microsoft's success.

WOA can only be acquired pre-installed on OEM hardware.
At first, I was disappointed, but then I looked around my lab and saw zero pieces of hardware that were ARM-based and would be easy to reimage. ARM processors are a licensed architecture, so when companies make ARM-based solutions, they aren't buying a processor and sticking it on a board. Rather, they’re building a completely customized solution centered on the ARM architecture. These custom solutions are called system on chips (SOCs). WOA will probably have a traditional hardware compatibility list, but it's not like these parts are consumer parts. That doesn't mean it won't happen someday, though.

While we tend to focus on tablets these days, the blog post actually referred to ARM PCs more than tablets. As we learn more about WOA and Metro, we can consider other uses beyond tablets -- perhaps as cheap desktop replacements, almost like thin clients, as applications move to Metro.

Desktop mode will exist, but only for special circumstances.
The traditional Windows desktop will be in WOA, but it appears that it will only be for ARM versions of legacy apps that couldn't be ported to the Metro interface, such as Office. You won't be able to use desktop mode for your own apps, which probably wouldn't need to be addressed anyway since they weren't written for ARM. Finally, it looks like you won't be able to buy or develop apps that run on the WOA desktop.

To further complicate things, there will also be x86/64 tablets, although Microsoft will distinguish between the two.
The last thing to note is that it's easy to get lost in the hype surrounding WOA, and that Windows 8, Metro and the desktop will be available on x86/64 tablets, and of course PCs. So, if you're scared off by all this, have no fear. Business as usual can still persist, and there's always desktop virtualization if you don't want to worry about what device to use in the cubicles.

Gabe Knuth
is an independent industry analyst and blogger, known throughout the world as "the other guy" at BrianMadden.com. He has been in the application delivery space for over 12 years and has seen the industry evolve from the one-trick pony of terminal services to the application and desktop virtualization of today. Gabe's focus tends to lean more toward practical, real-world technology in the industry, essentially boiling off the hype and reducing solutions to their usefulness in today's corporate environments.

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