Microsoft is releasing Windows 10 S, a new Windows variant designed to only run Windows Store apps, to MSDN subscribers today. The new operating system will be available in an ISO file so developers can download and install it to test their apps on Windows 10 S. Specifically, Microsoft wants education-focused developers to properly test Windows 10 S to make sure it’s ready for that particular audience. This is also a first step towards making Windows 10 S more broadly available to schools, as Microsoft promised back in May.

While anyone with an MSDN subscription will be able to download and test Windows 10 S now, Microsoft still isn’t making it available directly to consumers to switch to. It’s unlikely we’ll see that change, but Microsoft is making an Update Assistant Tool available next week that will include Windows 10 S. This tool is targeted towards schools, but it’s possible that anyone will be able to use it to download and test Windows 10 S.