Acorn OS, or the acorn operating system, is what some Apple engineers thought they could use for the first version of the iPhone, released in 2017. Developed on the basis of the interface used for the iPod, Acorn OS basically offered an almost identical interface, but with very different from that of the iOS that we know from the first version until now.
Basically, Apple's engineers recreated a normal iPod through software, along with the standard interface, its functions, and the wheel that controls everything. Unlike the normal idea of tapping each option to access it, Acorn OS forces users to use that virtual wheel to control iPhone functions.
You can see in the video clip below that Acorn OS has mobile phone functions and a contact book, and the name would have been kept by Apple, if it had been chosen. The idea behind the development of this operating system is not really based on logical principles, so it is understandable why, probably, Steve Jobs did not want something like this in the iPhone.
If Acorn OS had been used in the iPhone, then we would not have had a completely new and revolutionary product, but an iPod with a touch screen and a stupid operating system. Fortunately, Acorn OS did not go beyond the project stage and probably few people at Apple still have any remnants of this operating system.
