NEW YORK – Apple Inc. on Thursday released a developer preview of an update for the Mac operating system, dubbed "Mountain Lion," that will copy more features and apps from the iPhone and iPad to the Mac.

Apple said the new software will be on sale this summer, a year after it released the latest update, "Lion." The preview version will help software developers make products that take advantage of the new features of the operating system.

Mountain Lion will include Game Center, an iPhone app which stores high game scores and helps users find opponents. It will be integrated with iCloud, the new Internet storage service designed for the mobile devices.

The new Messages app, also copied from the mobile operating system, will replace iChat. Lion users can download a preview version of the app for free.

A new Notification Center will show alerts from email and calendar programs, just like on the iPhone.

Apple started the trend of making its Mac operating system more like its phone and tablet operating system, iOS, with the release of Lion. It borrowed phone features like a screen that shows all installed apps, and expanded the range of gestures that can be used to control a MacBook through the touchpad.

The Cupertino, Calif.-based company sells Lion for $30. It didn't say what Mountain Lion would cost.

Apple has been growing Mac sales in a nearly stagnant PC market, but the sales aren't growing as fast as those of the iPhone. In 2010, iPhone sales overtook those of Macs for the first time.

Apple has been using the names of big cats to differentiate its OS versions since 2001.

Microsoft Corp. is set to release Windows 8 later this year, and a preview version is already in developer hands. It, too, will be borrowing features from phone software, and one version of the operating system will run on phone-style chips, as opposed to the Intel-style chips that have been the bedrock of Microsoft software since the 1980s.

Shares rose $1.14 to $498.81 in afternoon trading.