IPhone 4 models. In fall 2010, pentalobe screws started to replace the Philips screws used in post-repair units in the US and in production units in Japan. The iPhone 4 shipped with iOS 4, which was the newest version of Apple's iOS mobile operating system at the time. iOS 4 introduced a multitasking system, allowing apps to remain "suspended" in memory, perform certain operations in the background, and allowing users to switch between apps using an on-screen menu. It also introduced FaceTime, which allows users to perform video calls between other iPhone, iPad, iPod Touch, and OS X users. The iPhone 4
IPod Touch (5th generation) were sold with the iPod Touch include the lanyard for the iPod Touch loop (not available for the 16 GB model). Andrew Williams from "TrustedReviews" noted the 5th generation iPod touch's common features with the iPhone 5, while praising the design and the respectable connectivity. Graham Barlow of "TechRadar" commended the improved screen, more color variants, greater quality earphones and the iPod's light weight while criticizing the "reset" of the lightning port. Scott Stein of CNET praised the enhanced camera quality and design, but remarked that the iPod touch is still weaker and outclassed compared to other iOS devices. IPod