NEW YORK (AP) — Apple Inc. will release its new operating system for Mac computers on Wednesday, with features borrowed from mobile devices and a tighter integration with online file storage.

Dubbed Mountain Lion, the new software narrows the gap between the PC and phone software packages, making Mac personal computers work more like iPhones and iPads.

It's similar to what Microsoft Corp. is doing with its forthcoming Windows 8 system. That system, to be released Oct. 26, will bring the look and user interface of Windows Phone to PCs.

Mountain Lion will cost $20 and will be sold only as a download. Only computers running the two most recent versions of Mac OS, Lion and Snow Leopard, can be upgraded.

Macs bought on or after June 11 can be upgraded for free.

Apple previously announced Mountain Lion's features, but it hadn't disclosed the exact availability date until Tuesday's release of its earnings for the April-June quarter. Apple provided no new details in that release.

Among the features of Mountain Lion:

— The new software will have better integration with social networks such as Facebook Inc.'s. It will have built-in features to facilitate sharing on Facebook, Twitter, Flickr and other services. For instance, you'll get notifications when you get a message or a mention in a Facebook or Twitter post. You need to sign in only once, and you can share directly from other apps you are using.