slot, all the ports on the 17-inch MacBook Pro are the same in type and number as on the 15-inch version. All models came with 4 GB of system memory that was upgradeable to 8 GB. Battery life was also extended further in this update, to an estimated 10 hours for the 13-inch and 8–9 hours on the 15- and 17-inch MacBook Pro computers. This was achieved through both greater power efficiency and adding more battery capacity. One reviewer reported about 6 hours of battery life through a continuous video battery stress test in the 15-inch and another, who called the battery life "unbeatable", reported nearer to 8 in the 13-inch through their "highly demanding battery drain test". Thunderbolt technology, Sandy Bridge dual-core Intel Core i5 and i7 (on the 13-inch model) or quad-core i7 (on the 15- and 17-inch models) processors, and a high-definition FaceTime camera were added on February 24, 2011. Intel HD Graphics 3000 come integrated with the CPU, while the 15- and 17-inch models also utilize AMD Radeon HD 6490M and Radeon HD 6750M graphics cards. Later editions of these models, following the release of OS X Lion, replaced the Expose (F3) key with a Mission Control key, and the Dashboard (F4) key with a Launchpad key. The chassis bottoms are also engraved differently from the 2010 models. The Thunderbolt serial bus platform can achieve speeds of up to 10 Gbit/s, which is up to twice as fast as the USB 3.0 specification, 20 times faster than the USB 2.0 specification, and up to 12 times faster than FireWire 800. Apple says that Thunderbolt can be used to drive displays or to transfer large quantities of data in a short amount of time. On June 11, 2012, Apple showcased its upgraded Mac notebooks, OS X Mountain Lion, and iOS 6 at the Worldwide Developers Conference (WWDC) in San Francisco. The new MacBook Pro models were updated with Ivy Bridge processors and USB 3.0 ports, and the default RAM on premium models was increased to 8 GB. Following this announcement, the 17-inch model was discontinued. After a media event on October 22, 2013, Apple discontinued all unibody MacBook Pros except for the entry-level 2.5 GHz 13-inch model. Apple discontinued the 13-inch aluminum MacBook Pro on October 27, 2016. Prior to its discontinuation it was Apple's only product to still include an optical drive and a FireWire port,