"Microsoft's move in creating its own tablet is the sign that PC manufacturers have lost the game," Renesse said. "The big question is, if Surface becomes as successful as the iPad, will Microsoft choose to stop licensing Windows on tablets?"
Microsoft's partners are mum. Hewlett-Packard Co. and Acer, both of which make PCs and tablets, had no comment on Microsoft's announcement. Samsung did not respond to requests for comment.
AP Business Writer Ryan Nakashima contributed to this report from Los Angeles.
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