Apple Mac OS X Mavericks OS released for free, available from Tuesday

Apple says its latest operating system for Mac computers is available free of charge, a knock to rival Microsoft, which is selling its Windows 8 Pro operating system for $199.

Apple Inc. made the announcement Tuesday at an event in San Francisco, where the company is also expected to unveil its latest iPads to round out its holiday gadget lineup.

Apple also says nearly two-thirds of its mobile devices are running iOS7, its latest operating system. Twenty million people have listened to iTunes Radio about a month after its release.

Apple is hoping to revive its tablet line with new iPads. The company sold 14.6 million iPads in the June quarter, down 14 percent from the same time last year.

Apple unveils iPad Air, iPad mini with Retina and new MacBooks