Microsoft Corp showed off a version of its next operating system at technology conferences in the United States and Taipei, as some PC makers grumbled over restrictions on their involvement in the development of the system.

The world's largest software company is expected to launch the new system, code-named Windows 8 and highlighting touchscreen features optimized for tablet computers, in the next 18 months, as it races to catch up with Apple Inc.

But Microsoft has told chipmakers who want to use the system for tablets to work with only one manufacturer to speed up the delivery, Bloomberg and Dow Jones news reported, sparking worries among some PC vendors that they will be left out.

In demonstrations at the D9 conference in Palos Verdes, California, and the Computex show in Taipei, Microsoft executives showed a starting page that resembles Microsoft's latest phone software, with live 'tiles' manipulated by pressing and swiping the screen.

The demonstration shows Microsoft is making progress toward the new operating system, which it promises will run on a range of hardware devices from traditional PCs to laptops and tablets, using both touchscreen and mouse and keyboard commands.

The company said in Palos Verdes that it was not out of the game in tablets, a view backed by some in the industry.

The fact that it's a year or two years after the iPad doesn't really matter. There is already a lot of built-in infrastructure, Adrian Crisan, Sony's director of engineering for VAIO and Mobile of America, told reporters in Taipei on Thursday.

Today Apple is first on one thing and Microsoft is first for another and, overall, it's going to be a race and whatever customers will like, they will buy.

Separately on Thursday, U.S. chip maker Qualcomm Inc said it would collaborate with Microsoft on the next version of Windows for its Snapdragon family of processors.

PC VENDORS UNHAPPY

Some Taiwanese vendors are concerned that the reported restrictions mean they would have to be chosen by chipmakers to make tablet PCs for the new Windows operating system. Previously PC vendors could choose their own partners.

By missing those chances, is it good for the whole industry together? This industry doesn't belong to Microsoft or Google, it belongs to all the participants, Jim Wong, president of world No.2 PC vendor Acer Inc told a news conference in Taipei on Wednesday.

So they can't make the decision for all of us. That's the problem, Wong said.

Sony's Crisan declined to comment on the reported restrictions, but said Windows 8 would probably eventually be opened to everyone.

On Wednesday, Steven Sinofsky, the head of Microsoft's Windows unit, said the new system did not yet have a name and did not say when it would be available. He promised more details at a developers' conference in September.

The release date is a Defense Department secret, joked Sinofsky, adding that it would not be this autumn.

Microsoft typically aims for 24 to 36 months between major Windows versions, suggesting a launch date for the next Windows between October 2011 and October 2012.

Sinofsky said Microsoft is working to integrate Internet telephone service Skype into the new system, following its agreement to purchase the company last month.

He had shown a crude version of the new Windows system working on ARM Holdings chips -- which work better on mobile devices due to their low power requirements -- at the Consumer Electronics Show in January.

That signaled a change in emphasis for Microsoft toward mobile devices, although the new Windows will still run on chips made by traditional partner Intel Corp.

(Reporting by Sarah McBride and Bill Rigby in Palos Verdes, and Lee Chyen Yee and Clare Jim in Taipei; editing by Jonathan Standing and Vinu Pilakkot)

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