IPhone OS 1.0 Acorn builds

iPhone OS 1.0 Acorn builds or AcornOS are early prototype builds of iPhone OS 1.0. There are currently 2 known AcornOS builds, both of which remain unleaked, shown by Sonny Dickson on January 2017.

Interface
One build has a very similar appearance to the operating system used on the iPod; this build was likely for a test with the iPod touch. Another build used a menu with squared buttons.