Software
The iPhone, iPod Touch and iPad run an operating system known as iOS (formerly iPhone OS). It is a variant of the same Darwin operating system core that is found in Mac OS X. Also included is the "Core Animation" software component from Mac OS X v10.5 Leopard. Together with the PowerVR hardware (and on the iPhone 3GS, OpenGL ES 2.0), it is responsible for the interface's motion graphics. The operating system takes up less than half a gigabyte.
It is capable of supporting bundled and future applications from Apple, as well as from third-party developers. Software applications cannot be copied directly from Mac OS X but must be written and compiled specifically for iOS.
Like the iPod, the iPhone is managed from a computer using iTunes. The earliest versions of the OS required version 7.3 or later, which is compatible with Mac OS X version 10.3.9 Panther or later, and 32-bit Windows XP or Vista. The release of iTunes 7.6 expanded this support to include 64-bit versions of XP and Vista, and a workaround has been discovered for previous 64-bit Windows operating systems.
Apple provides free updates to the OS for the iPhone through iTunes, and major updates have historically accompanied new models. Such updates often require a newer version of iTunes—for example, the 3.0 update requires iTunes 8.2—but the iTunes system requirements have stayed the same. Updates include bug fixes, security patches and new features. For example, iPhone 3G users initially experienced dropped calls until an update was issued.
Version 3.1 required iTunes 9.0, and iOS 4 required iTunes 9.2. iTunes 10.5, which is required to sync and activate iOS 5, the current version of iTunes, Requires Mac OS X 10.5.8 or Leopard on G4 or G5 computers on 800 MHz or higher; versions 10.3 and 10.4 and 10.5–10.5.7 are no longer supported.
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