Another interesting detail on the prototype, which lacks an Apple logo on the back, is the presence of a 30-pin dock connector, suggesting it was designed before Apple formally adopted Lightning.

First Connector (digital + analog) The 30-pin connector worked with Apple devices prior to the iPhone 5 and 2012 models of the iPod touch and nano. It had 27 lines for digital data and three lines ...

Each of these adapters lets you connect 30-pin-dock-connector accessories to the latest iPhone and iPod models by offering a Lightning-connector plug on one end and a female 30-pin port on the other.

Along with it goes the 30-pin dock connector, marking a complete transition to the Lightning connector for Apple's entire mobile device fleet in exactly two years. The iPod classic was part of ...