Microsoft unveils Windows 8.1 at Build conference Rip it up and start again. That was Microsoft's approach to Windows 8, the latest version of the operating system that powers the vast majority of the world's computers. Released in October, the software is designed to work best on tablets and smartphones, a clear response to domination of the mobile market by Apple and Google's Android. But what of desktop and laptop users? If you want to boot to the desktop, you can boot to the desktop. Microsoft CEO Steve Ballmer Today at the Microsoft Build developer event, the company sought to address a string of complaints from those users -- complaints that may be partly responsible for the largest slump in PC sales since records began in 1994, despite the fact that Microsoft has said it has sold more than 100 million Windows 8 licenses so far. If I was to put it in coffee terms, [consumers said] why don't you go refine the blend? Microsoft CEO Steve Ballmer told the crowd Wednesday. Make it easier to start applications the way we're used to. That's just what the company has done. Called Windows 8.1 and launched exactly 8 months after Windows 8 went on sale, the free update is available today in beta form for Microsoft partners and other technology partners; it will also be freely available for anyone to test, via the Windows Store software in Windows 8. The new operating system adds back a version of the familiar Start button that was stripped from the OS in Windows 8, and introduces a feature that lets users boot straight to the desktop, among other updates, Ballmer said. "If you want to boot to the desktop, you can boot to the desktop," he told the crowd, to applause. A version of the Windows 8.1 update meant for the general public will come out later in the year, as well, though a specific date hasn't been announced. Many of the new features have been shown off already. But the three-day Build conference, which starts Wednesday in San Francisco, will give Microsoft developers a chance to learn more about the new system and try it out. It also will give the company a chance to explain some of the reasoning behind the update and sell developers on Microsoft's ambitions to regain relevance lost to Apple's iPad and various devices running Google's Android software. There's also speculation that Microsoft could show off a new, smaller version of its Surface tablet computers. One of the new features in Windows 8.1 is the ability to work well on smaller-screen devices. Windows 8, which was released Oct. 26, was meant to be Microsoft's answer to changing customer behaviors and the rise of tablet computers. The operating system emphasizes touch controls over the mouse and the keyboard, which had been the main way people have interacted with their personal computers since the 1980s. But some people have been put off by the radical makeover. Among the complaints: the lack of a Start button on the lower left corner of the screen. In previous versions of Windows, that button gave people quick access to programs, settings and other tasks. Microsoft replaced that with a tablet-style, full-screen start page, but that covered up whatever programs people were working on, and it had only favorite programs. Extra steps were needed to access less-used programs. Settings, a search box and other functions were hidden away in a menu that had to be pulled out from the right. How to do that changed depending on whether a mouse or touch was used. And while Microsoft has encouraged people to use the new tablet-style layout, many programs -- including Microsoft's latest Office software package -- are designed for the older, desktop mode. People were forced into the tablet layout when they start up the machine and had to manually switch the desktop mode each time. Although Microsoft is addressing much of the criticisms with Windows, it is positioning the update as more than just a fix-up job. From its perspective, the tuneup underscores Microsoft's evolution into a more nimble company capable of moving quickly to respond to customer feedback while also rolling out more innovations for a myriad of Windows devices -- smartphones, tablets or PCs. It's crucial that Microsoft sets things right with Windows 8.1 because the outlook for the PC market keeps getting gloomier. IDC now expects PC shipments to fall by nearly 8 percent this year, worse than its previous forecast of a 1 percent dip. IDC also anticipates tablets will outsell laptop computers for the first time this year.