This looks like one that will run through the courts for decades to come, but with its dominant position in desktop class processes in serious jeopardy, Intel has responded to the impending arrival of Windows 10 ARM, touting its full armoury of patents and history of successfully defending its IP.
At question is x86 emulation, which will allow ARM-based Windows 10 PCs to run standard Win32 software without developers needing to recode. That's going to be an important facet of Windows 10 ARM adoption in future - given the previous and massive failure of Windows RT. The older ARM-based Windows could only run Windows Store apps, a key weakness that brought about its downfall.
Intel has been talking tough about Qualcomm, whose SnapDragon 835 CPU is likely to be the power behind the first ARM-based Windows devices, but the emulation is provided by Microsoft,using a 'just-in-time' emulator call Windows on Windows, which builds a ARM x64 version of the software its emulating on the fly.
How this plays out will be interesting. Microsoft has positioned itself to rapidly grow the number of Windows Store UWP apps by virtue of the (x86-based) Windows 10 S and it's restriction on using non-Windows Store software.
With Windows 10 S likely to replace Windows 10 Home as the default Windows SKU for consumers, education and even some enterprises there are good reasons why developers will want to get their apps into the Windows Store as soon as possible. With major announcements from Apple and Spotify already supporting that theory, the number and quality of Windows Store apps is only going to rise.
Those ARM-based PCs - likely to be popular due to better portability and improved battery life - only growing the market for UWP software the use of x86 emulation is likely to be short lived and really only required for legacy applications which have become abandonware.
Intel has a very short window of opportunity to do something about this and some very real risks involved if it kicks up too much of a stink. Microsoft has a pressing need to make Windows 10 ARM work now that Apple has woken up to the potential of the iPad as a computer. Putting obstacles in the way could prove to be a painfully short strategy.
Microsoft could move Windows to ARM exclusively (unlikely). It could favour other x86 processor vendors in both the desktop and server market; it could, in short, play merry hell with Intel's major income streams.
By killing development of the low-end Atom processor, Intel forced Microsoft into the arms of ARM. At this point it's best long term strategy is to licence ARM and compete head to head with Qualcomm for those valuable Windows OEM deals. Or revive the Atom processor, adding in some of the benefits which make SnapDragon so appealing to OEMs on phones and tablets.
Litigation at this point suggests Intel doesn't have the technical know-how or strategy to compete, which seems unlikely but which promises to be an extinction level shortcoming if true.