When Apple first announced the iPhone, 10 years ago this week, it showed off a device with now-familiar app icons and a natural touchscreen interface. But that wasn't always the plan — internally, Apple had different teams competing on different projects to find the best operating system for its new device. We got our first look at one of these systems last week, a click wheel prototype designed by Tony Fadell and his team, and known as P1. Now we've seen another: a very early version of the touchscreen operating system, codenamed P2, that would become iOS.

The video above, recorded by Sonny Dickson, show P1 and P2 running next to each other. P1 — running what Dickson calls "AcornOS" — boots up faster than P2, but it's the second device that runs a more familiar operating system to modern iPhone users, albeit a very basic version. Giant blue icons appear on a white background, offering touchscreen options for calls, SMS, and "Other" — a menu that leads to Music, Network, and Preferences, among other choices. Other images shared by Dickson show further options, including a toggle for Airplane mode and a phone dial screen.

The video shows a true touchscreen interface

Where P1 was the work of "the father of the iPod," Tony Fadell, and his team, P2 was developed by a group led by Scott Forstall — the then-leader of Mac development within the company. As history has shown, Forstall's prototype won the competition between the teams inside Apple, leading to the creation of the first consumer version of iOS.

As Dickson notes, these prototype devices were never meant to be seen outside of Apple's walls. But these early prototypes are also key elements of Apple's history, marking a fork in the road that helped make the iPhone Apple's most important product, and change the way we use smartphones.