Microsoft on Thursday issued invitations to a Jan. 21 media event slated to reveal more of the features of the Windows 10 operating system. In the event, to be held at Microsoft's headquarters in Redmond, Wash., is expected to present consumer-focused functions, including Cortana, the digital voice assistant now featured in Microsoft's Windows Phone smartphones.

Microsoft has pitched Windows 10 as a unified replacement for its lineup of Windows for phones, tablets and personal computers. It positions the new software as the base for all Windows-powered devicess.

Microsoft plans to shape the shape the new OS based on the user feedback, so it is runnig a preview program, aimed mainly for developers.

A Microsoft executive recently said Windows 10 will be released by early next fall, but the company has been teasing by revealing the product?s features.

In September, Microsoft offered the first public peek at Windows 10 - user interfaces for Windows 10 that looked more like the popular Windows 7 version released five years ago.