LOS ANGELES — Microsoft unveiled a new tablet computer, Surface, that attempts to take advantage of one of the few criticisms of Apple’s iPad — that it is better for consuming content than creating it.

The software maker said Monday that its device will attach to a removable rubberized keyboard that also acts like a book cover. CEO Steve Ballmer said Surface will be an entertainment device “without compromising the productivity that PCs are uniquely known for.”

Microsoft’s broadside against the Apple iPad is a dramatic step to ensure that its Windows software plays a major role in the increasingly important mobile computing market.

“They are saying it’s a different world now and are trying to put the sexy back into the Microsoft brand,” said Gartner analyst Carolina Milanesi.

Microsoft is linking the Surface’s debut with the release of its much-anticipated Windows 8 operating system, which has been designed with tablets in mind. The company hasn’t specified when Windows 8 will hit the market, but most analysts expect the software to come out in September or October.

One version of the Surface, which won’t go on sale until fall, is 9.3 millimeters thick and works on the Windows RT operating system.