Microsoft revealed in January that devices running Windows RT, including the company's own Surface RT tablets, won't get an update to Windows 10. At the time, the software maker said it was "working on an update for Surface, which will have some of the functionality of Windows 10." That update will now arrive in September, according to Microsoft's Gabe Aul. Dubbed "Windows 8.1 RT Update 3," it's not really clear what new functionality the update will bring. We reached out to Microsoft, but a spokesperson simply revealed the company will have "more to share soon."

@jon5798 Windows 8.1 RT Update 3 will be available in September — Gabriel Aul (@GabeAul) July 15, 2015

Microsoft has effectively rendered Windows RT dead, and no third-party OEMs are making tablets using the failed operating system anymore. The software giant refuses to discuss details of the mysterious update, but it could involve rolling out some of the built-in Windows 10 universal apps to Windows RT. A similar situation occurred with Windows Phone 8, leaving Windows Phone 7 with no direct upgrade path. Microsoft supplied a Windows Phone 7.8 update to provide some functionality like an updated Start Screen, but most of the new features were only available on Windows Phone 8 devices.