AROS Research Operating System (AROS) is a free software/open source implementation of the AmigaOS 3.1 APIs. Designed to be portable and flexible, ports are currently available for x86-based and PowerPC-based PCs in native and hosted flavors, with other architectures in development.
The project, started in 1995, has over the years become an almost "feature complete" implementation of AmigaOS - with currently (as of October 2008) only a few lacking areas of functionality. This was achieved by the efforts of a small team of developers.
It can currently be installed on most IBM PC compatibles, and features native graphics drivers for video cards such as the GeForce range made by Nvidia. As of May 2007 USB keyboards and mice are also supported. AROS has been ported to the PowerPC board SAM4404EP from ACube Systems and is also planned to run on Efika.
While the OS is still lacking in applications, a few have been ported, including E-UAE, an emulation program that allows 68k-native AmigaOS applications to run in the same way a majority must be run on AmigaOS 4.0. Some AROS-specific applications have also been written. AROS has TCP/IP networking support, and has available an experimental version of AMosaic web browser, for test purposes, among other Internet-related applications.
AROS is designed to be source-compatible with AmigaOS, but not binary-compatible. Source code that will compile on AmigaOS should compile on AROS, but binaries already compiled for AmigaOS will not run, even if they are compiled for the same family of CPU. This means that, unlike MorphOS or AmigaOS 4, AROS is not capable of running legacy software directly, only applications compiled for AROS. There are plans to integrate the Amiga emulator E-UAE directly into AROS to run AmigaOS applications, and even a bounty to run MorphOS software on the PowerPC build of AROS, but so far (January 2008) these objectives remain elusive.
The aim of AROS is to remain aloof of the legal and political spats that have plagued other AmigaOS implementations by being independent both of hardware and of any central control. The de-facto motto of AROS, "No schedule and rocking" both lampoons the infamous claim of Amiga, Inc. CEO Bill McEwen that AmigaOS 4 was "On schedule and rocking" (despite not existing at this time), and declares a lack of the formal deadlines that are traditionally broken by other AmigaOS clones.