At Wednesday's Windows 10 event, Microsoft went over a large amount of information regarding its new operating system, but something it didn't reveal is what will happen to its previous ARM-powered operating system for tablets – as well as two of its own tablets.
Microsoft notably said nothing during its demonstrations about Windows RT, the version of its Windows 8 operating system designed for ARM-powered devices. Following the event, Terry Myerson, head of Microsoft's operating systems team, answered a question about the omission by saying Microsoft is "working on an update for Windows RT," though he didn't elaborate.
In a statement later provided to CNET, Microsoft said its "entire Surface Pro" lineup will be upgradeable to Windows 10, but that the ARM-powered Surface line will receive an update that "will have some of the functionality of Windows 10."
The statement is notable in that it specifically mentions the update will merely have parts of Windows 10's functionality, meaning it won't actually be Windows 10. This would further mean Microsoft's Surface and Surface 2 tablets won't get its newest operating system, as they both run Windows RT.
An ARM version of Windows 10 does exist, however, just not on tablets. Microsoft's Windows Phone 8 line will be updated to the smartphone version of Windows 10, and that operating system currently runs exclusively on ARM processors – Qualcomm's Snapdragon line, specifically.
The decision not to transition Windows RT to Windows 10 is similar to a previous Microsoft dilemma, when it declined to upgrade Windows Phone 7 smartphones to Windows Phone 8. Instead of updating the devices to the new operating system, Microsoft released Windows Phone 7.8, which added some of the features of the newer operating system but still lacked compatibility with its newer apps.