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 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:
-- Power Nap keeps your Mac updated even while it's in power-saving "sleep" mode. It will get your email messages, back up your files and download software updates automatically. It will work with recent MacBook Air computers and the higher-end MacBook Pro model, the one with the sharper, "Retina" display.
-- A new Messages app, copied from Apple's mobile operating system, will replace iChat. It will allow you to send messages to other Apple users, whether that person is on a Mac or an Apple mobile device.
-- Mountain Lion will be integrated with iCloud, the new Internet storage service designed for the mobile devices.
-- The software will bring dictation to Macs, essentially allowing the computer to type as you talk.
-- Game Center will store high game scores and help users find opponents on both Macs and Apple mobile devices.