The SDK is a comprehensive suite that provides everything needed to build, debug, and test mobile apps:

: Virtual device images for testing, including updated 256MB and 512MB RAM configurations in the 7.1.1 patch.

The SDK was designed for older versions of Windows, which can make installation on modern systems tricky:

: Tools for building 2D and 3D games for the phone.

: You can still find the Windows Phone SDK 7.1.1 Update on the Microsoft Download Center, though this is an update that requires the base 7.1 SDK to be installed first.

: The primary framework for building application UIs.

Архив загрузок Windows SDK - Windows apps - Microsoft Learn