The AmigaOS is known for combining the functionality of OS and window manager. It was primarily designed to run on PowerPC Amiga systems or hardware equipped with Cyberstorm PPC or BlizzardPPC accelerator boards as well as AmigaOne computers with PPC Teron installed. This system was only available in developer pre-releases for several years until the final release in December 2006. Since 2001, Hyperion Entertainment has been developing new AmigaOS 4 running on PowerPC-based systems. The contract between Amiga Inc. and this Belgian-German company only allowed for the availability of the commercial AmigaOS 4 license to computers with AmigaOne motherboards.