IPhone (1st generation) $499, the original launch price of the 4 GB model. Apple released an SDK on March 6, 2008, allowing developers to create the apps that would be available starting in iPhone OS version 2.0, a free upgrade for iPhone users. On June 9, Apple announced the iPhone 3G, which began shipping July 11. The original iPhone was discontinued 4 days later; total sales volume came to 6,124,000 units. During release, the iPhone was marketed as running "OS X". The name of the operating system was revealed as iPhone OS with the release of the iPhone SDK. The original iPhone supported
IPhone its successor required only 1.3 GB. The interface is based around the home screen, a graphical list of available applications. iPhone applications normally run one at a time. Starting with the iPhone 4, a primitive version of multitasking came into play. Users could double click the home button to select recently opened applications. However, the apps never ran in the background. Starting with iOS 7, though, apps can truly multitask, and each open application runs in the background when not in use, although most functionality is still available when making a call or listening to music. The home screen can