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 screens on the first three generations have a resolution of 320×480 (HVGA) at 163 ppi; those on the iPhone 4 and iPhone 4S have a resolution of 640×960 at 326 ppi; the 4-inch models, with 640×1136 at 326 ppi; the 4.7-inch models, with 750×1334 at 326 ppi; the 5.5-inch models, with 1080×1920 at 401 ppi; and the 5.8-inch model X, with 1125×2436 at 458 ppi. The initial models were using twisted-nematic (TN) LCDs. Starting with iPhone 4, the technology was changed to in-plane switching (IPS) LCDs. The iPhone 5 model's screen results in an aspect ratio of approximately 16:9. The