Microsoft Corp. unveiled its first tablet computer, a sign of the new tactics the company is taking on as it tries to make up lost ground in the market for mobile devices.

Speaking at an event for journalists in Hollywood, Calif., Microsoft Chief Executive Steve Ballmer and other executives showed off several versions of new tablet computer, called Surface, that will run versions of Microsoft's coming Windows 8 operating system.

Windows 8 is the first time Microsoft is rebuilding its flagship computer software with tablet computers in mind. Executives hope Windows 8 will continue Microsoft's efforts to catch up to Apple Inc. and Google Inc. in smartphones and tablet devices--two fast-growing computing markets where Microsoft's market share is negligible.

The Surface tablet is 9.3 millimeters thick and weighs 1.5 pounds, which is similar to Apple Inc.'s iPad (9.4 mm and 1.44 pounds). The Surface has a built-in kickstand and magnetic cover, which also acts as a touch keyboard.

Surface will 'be priced like comparable tablets,' said Windows boss Steve Sinofsky, at the event. But he didn't say when it would be available through online retailers.

Microsoft executives said the company's decision to make a homegrown tablet computer fits with the history of Microsoft making hardware when it is needed to bolster the company's software--such as Microsoft's making one of the earliest computer mice.

'We wanted to give Windows 8 its own companion hardware innovation,' Mr. Ballmer said at the event.

But by making its own tablet, Microsoft also risks taking sales away from a coming crop of Windows-powered tablets from its own allies.

Microsoft traditionally has left the making of computers to partners such as Dell Inc., Hewlett-Packard Co. and Lenovo Group Ltd. Microsoft treading on the hardware-makers turf threatens to strain that longstanding business arrangement. The computer makers' business is dependent on Microsoft, so they may not express annoyance publicly at Microsoft's trading on the hardware makers' turf. But at least some hardware executives are fuming privately at Microsoft's decision.

Microsoft's move to make its own tablet 'comes with consequences, which is complicating choices for consumers and complicating relations with third-party manufacturers,' said Sarah Rotman Epps, an analyst with Forrester Research Inc.

Mr. Ballmer sought to underscore Microsoft's longstanding and continued tight alliances with hardware companies. 'Those partnerships are essential to the reimagination of Windows,' Mr. Ballmer said.

Microsoft showed off the three versions of the Surface tablet, and Microsoft said the device will be powered by chips made by Intel Corp. as well as those licensed from ARM Holdings PLC, the variety of chips that power the iPad.