Microsoft Windows 8 who declined to be named

Microsoft will finish work on Windows 8 this summer, setting the stage for personal computers and tablets with the operating system to go on sale around October, according to sources with knowledge of the schedule.

The initial rollout will include devices running Intel and ARM chips, making good on Microsoft's promise to support both standards, said the sources, Microsoft Windows 8 who declined to be named because the plans are confidential. In embracing ARM technology, Microsoft is using the same kind of processors as Apple's iPad. Still, there will be fewer than five ARM devices in the debut, compared with more than 40 Intel machines.

The timing would let Microsoft target Christmas shoppers with the new software, which works with touch-screen devices as well as laptops and desktop PCs. Microsoft, which has not announced timing for the Windows 8 release, aims to take back sales lost to the iPad and reinvigorate the sluggish PC market.

"If they miss the September-October timeframe, they're going to be stuck without being able to ship anything in 2012," said Mr Michael Gartenberg, an analyst at Gartner Inc. "The last thing Microsoft wants to have is a situation where there are no compelling Windows tablets at a time when the new iPad looks like it's going to be a good seller for the holidays."

Microsoft will host an event for its industry partners early next month, the sources said. The company will spell out its release strategy for Windows 8 , giving more details on timing and marketing, they said.

There will be fewer ARM-based devices in the rollout because Microsoft has tightly controlled the number and set rigorous quality-control standards, said one of the people. The new version of Windows will be the first to use ARM processors, which are most commonly found in smartphones. Windows 7, the current version, only works with Intel's technology. Three of the Windows 8 ARM devices will be tablets, the sources said.

Spokesmen for Microsoft and Intel declined to comment. Representatives of Nvidia, Texas Instruments and Qualcomm - the three chip companies supplying ARM-based processors - referred questions on the availability of devices to Microsoft.

Mr Steven Sinofsky, president of the Windows business, has said that Microsoft plans to have both ARM and Intel-based systems available when Windows 8 is released. "Our collective goal is for them to ship at the same time," he said last month. "I wouldn't be saying it's a goal if I didn't think we could do it."