"It addresses a lot of the issues that people that I talk to had about Windows 8," said Charles Madison, a software developer from New York.
Other new features of Windows 8.1 include more options to use multiple apps. People will be able to determine how much of the screen each app takes while showing up to four different programs, rather than just two. The update will also offer more integrated search results, showing users previews of websites, apps and documents that are on the device, all at once.
Microsoft also touted a broadening array of applications specifically written for Windows 8, among them one from Facebook.
Frank Gillett, an analyst with research firm Forrester, said that with 8.1, Microsoft is doing a better job of uniting the Desktop and Modern screens, but the changes don't run deep.
"They smoothed off some rough edges, but they don't fundamentally change the experience of having two experiences within one operating system," he said.
The preview version of Windows 8.1 is meant for Microsoft's partners and other technology developers, but anyone can download it. The release comes exactly eight months after desktops, laptops and tablets with Windows 8 went on sale. The version of the Windows 8.1 update meant for the general public will come later in the year, though the company hasn't announced a specific date.
Julie Larson-Green, the head of Microsoft's Windows division, said the update, rapid by Microsoft standards, "shows how much more responsive our engineering has become".
Many of the new features have been shown already. A three-day Build conference, which started Wednesday in San Francisco, gives 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.
One big problem is the fact that Windows 8 doesn't work well on smaller screens, making Windows tablets less competitive with cheaper tablets such as Apple's iPad Mini, Google's Nexus 7 and Amazon's Kindle Fire HD. Microsoft built Windows 8 primarily to run on tablets with 10-inch to 12-inch screens, and it is trying to address that shortcoming in Windows 8.1.
The update automatically makes adjustments to programs based on a device's screen size. Smaller screens can now do split-screen multitasking. To reinforce the point, Microsoft promised to give all 6000 conference attendees an Acer tablet with an 8.1-inch screen running the full Windows 8.1. The device sells online for $US350.
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 per cent this year, worse than its previous forecast of a 1 per cent dip. IDC also anticipates tablets will outsell laptop computers for the first time this year.
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