Windows on ARM has not been universally popular. When first announced a week shy of three years ago, the prospect of Windows running on ARM processors piqued many people's interest, particularly around what software it would be able to run, and what hardware it would be able to run it on.

That interest rapidly waned when it landed in users' hands. Windows RT, as Windows on ARM was branded for its release, could only run new-style touch friendly Metro applications, which were few and far between. The extensive body of traditional Windows applications built for x86 processors was, not entirely surprisingly, off limits.

With Intel forcing down the price of x86 tablets through heavy subsidies for its Atom processors, the limited appeal of Windows RT—"Windows without Windows software"—was further diminished. It's not altogether surprising, then, that Windows on ARM didn't take the world by storm. Microsoft quietly confirmed that it had stopped producing Surface 2s last week, and this week it did the same for its other ARM tablet: the Lumia 2520, which Microsoft inherited when it bought Nokia's devices division.

On top of all this, these tablets are apparently not on track to receive Windows 10. While Microsoft has said that extant Windows RT devices will receive some kind of software update and that they'll get some Windows 10 features, exactly which features and when is presently a mystery. We argue that they should receive the desktopless, pure Metro Windows 10 for small tablet SKU, as it would be a natural fit for a platform that can't run Windows desktop software anyway, but this might be a bigger effort than Microsoft wants to make.

All this seems pretty ominous for Windows on ARM. But other news this week suggests that there may be life in the, er, young dog yet.

The Raspberry Pi 2, announced yesterday, is a second generation of ultra-cheap ARM computers packed full of ports and connectivity. The first generation Raspberry Pi was for the most part a Linux machine, with the recommended operating system being a specially modified version of Debian. The Pi 2's upgraded processor opens up more operating system possibilities. One of these is Ubuntu for ARM.

Another is Windows 10. The $35 machine will run Windows 10, and Microsoft has confirmed that the operating system will be free. The "free" part isn't actually a surprise; the company said that Windows would be free on Internet of Things devices at BUILD last year. Microsoft has been making efforts to engage with the maker community, supporting Windows on Intel's Galileo boards. Adding the Raspberry Pi 2 is a logical extension of this, with the cheap ARM boards more popular than Intel's offerings.

Supporting the Pi 2 means, of course, that Microsoft is continuing to support Windows on ARM. But it's probably not the same kind of Windows that Windows RT was. At TechEd Europe last year, Microsoft described its Windows 10 Internet of Things offerings, and Mary Jo Foley has a picture of a slide describing three different Windows 10 releases: "Industry," "Mobile," and "Athens."

"Industry" is the full version of Windows, albeit with additional modularization and lockdown features. This is a continuation of the Windows Embedded version that has existed for a long time, and will support both regular Win32 and new "Modern" apps.

"Mobile" is the embedded counterpart to Windows 10 for phones and small screen tablets. It's not widely publicized, but Microsoft already has an "embedded" version of Windows Phone that hardware companies can use for things that are similar to, but not identical to, smartphones—think gizmos with integrated laser barcode readers for stocktaking, or magnetic stripe readers for credit cards, or whatever else an industrial appliance might need. The "Mobile" version is the Windows 10 equivalent: it'll be more or less the same as the desktopless, Modern app-only phone/small tablet version of Windows 10, but aimed at industrial devices.

"Athens" is a successor to the Windows 8 for Internet of Things versions currently available for the Galileo boards. It's pretty cut down, for example lacking the full Windows UI, designed for highly resource constrained devices. It's most likely that it's this "Athens" version that will run on the Raspberry Pi 2. Although the Pi 2's specs are relatively high—including a full 1GB of RAM—it's hard to imagine that Microsoft would want to offer a reasonably full version of Windows for a $35 device. Exactly what is and isn't going to be available on this version is currently unknown.

The other important detail Microsoft revealed about the different versions is their processor support. "Industry" is x86-only. "Mobile" and "Athens" are both available for both x86 and ARM. This too isn't surprising. In the smartphone space, ARM is still king, and while x86 has made some inroads into tablets, ARM is still critical there, too. The "Mobile" version has to support ARM. What's perhaps more interesting is that it also supports x86; this suggests that Microsoft has everything in place to support x86 phones should it want to.

The same is broadly true of "Athens." Internet of Things devices will, more likely than not, use ARM processors. To be able to play in this space, Microsoft had to support ARM.

All this means Windows on ARM isn't going away. It really can't. Microsoft still wants Windows Everywhere, and for Windows to be Everywhere, ARM support is entirely non-negotiable. It just won't necessarily be in the same kind of consumer tablets as it was in the Windows 8 timeframe.

But then again, it might. A mysterious Windows tablet has posted some benchmark scores for the GFXBench 3D graphics benchmark. It has a Qualcomm ARM processor, a 2560×1440 10.1 inch screen, and a peculiar 55GB storage (perhaps the result of some weird partitioning scheme).

There's no guarantee that this device will ever come to market, of course. It might, for example, be a reference test system used to validate the processor or the operating system. But equally, it could be a preproduction unit for something that we'll eventually be able to buy. And if it is, it seems that it's running the spiritual successor to Windows RT.

Windows on ARM may look dead right now. Chances are that it's only sleeping.