Microsoft will release a preview of Windows 8.1 at its annual developers conference. The free update promises to address some of the issues people have with the Windows 8 OS. The Build conference, which starts Wednesday in San Francisco, will give Microsoft's partners a chance to learn more about the new system and try it out.

There's also speculation that Microsoft could show off a smaller version of its Surface tablet computers, taking advantage of the native support for small screen devices offered by Windows 8.1.

Windows 8.1 will be released to the general public later in the year, though a specific date hasn't been announced.

Users have been complaining that Microsoft's Windows 8 OS lacks a Start button on the lower left corner of the screen and that settings, a search box and other functions were hidden away in a menu that had to be pulled out from the right. Microsoft will not restore the traditional start button but it will restore a logo in that spot and will let users add favorite applications, such as Word and Excel, to a horizontal tool bar while working in the desktop mode.

And while Microsoft has encouraged people to use the new tablet-style layout, many programs are designed for the older, desktop mode. Windows 8 users had to use the tablet layout when they started up the machines and then to manually switch the desktop mode each time. Windows 8.1 will allow people to start in the desktop mode automatically. In that mode, it is restoring a button that resembles the old Start button.

Other new features of Windows 8.1 include more options to use multiple apps and more integrated search results.

The 8.1 update will include a built-in connection with Microsoft's online storage system, SkyDrive, to back up photos, music and program files.

Internet Explorer 11, the next generation of Microsoft's Web browser, will also come with Windows 8.1.