Editing A2 (operating system)

{{Use dmy dates|date=February 2021}}
{{Infobox OS
| name = A2
| logo =
| screenshot = 
| caption = 
| developer = [[ETH Zurich]]
| family = [[Oberon (operating system)|Oberon]]
| source model = [[Open-source software|Open source]]
| released = {{Start date and age|2002}}
| latest release version = 
| latest release date = {{Start date and age|2012}}
| kernel type = [[Object-oriented operating system|Object-oriented]]
| supported platforms = [[IA-32]], [[x86-64]], [[ARM architecture|ARM]], [[Cell (microprocessor)|Cell]]
| license = [[BSD licenses|BSD-like]] ETH A2 License<ref>{{cite web |url=http://www.a2.ethz.ch/license.html |title=License |access-date=2014-01-07 |url-status=dead |archive-url=https://web.archive.org/web/20120807103036/http://www.a2.ethz.ch/license.html |archive-date=2012-08-07}}</ref>
| working state = Current
| website = {{URL|https://gitlab.inf.ethz.ch/felixf/oberon}}
}}

A2 (formerly Active Object System (AOS) and later Bluebottle) is an object-oriented operating system developed at [[ETH Zurich]]. It includes features such as garbage-collected [[memory management]] and a zooming user interface.<ref name=":0" />

== History ==
A2 is a successor to [[Native Oberon]], the [[x86]] [[IBM PC compatible|PC]] version of [[Niklaus Wirth]]'s [[operating system]] [[Oberon (operating system)|Oberon]].<ref>{{cite journal |last1=Wirth |first1=Niklaus |author1-link=Niklaus Wirth |last2=Gutknecht |first2=Jürg |author2-link=Jürg Gutknecht |date=September 1989 |title=The Oberon System |journal=Software: Practice and Experience |volume=19 |issue=9 |pages=857–893 |doi=10.1002/spe.4380190905|s2cid=44292990 }}</ref><ref name=":0">{{cite book |last=Reiser |first=Martin |year=1992 |title=The Oberon System: User Guide and Programmer's Manual |publisher=[[Addison-Wesley]] |isbn=0-201-54422-9}}</ref><ref>{{cite book |last1=Wirth |first1=Niklaus |author1-link=Niklaus Wirth |last2=Gutknecht |first2=Jürg |author2-link=Jürg Gutknecht |year=1992 |title=Project Oberon: The Design of an Operating System and Compiler |publisher=Addison-Wesley |isbn=978-0201544282}} Out of print. [https://inf.ethz.ch/personal/wirth/ProjectOberon1992.pdf Electronic reprint.]</ref> It supports [[multiprocessing]] computers, and provides soft [[real-time computing]] operation. It is entirely written in [[Active Oberon]]. 

According to ETH Zurich’s documentation, A2's architecture supports the development of systems using active objects that operate directly on hardware, without relying on an [[Interpreter (computing)|interpreter]] or [[virtual machine]].In the Active Oberon model used by A2, active objects combine conventional object-oriented structures with independently executing threads, allowing for parallelism within the operating system. In the Active Oberon implementation, an active object may include activity of its own, and of its ancestor objects. 
[[File:Oberon A2Desktop Screen.png|thumb|The Oberon A2 desktop screen with the installer application open, along with a calendar and clock. (Using the default style)]]

The A2 system is written in a type-safe [[language]] with automatic memory management, and its design emphasizes modularity and simplicity, according to project documentation, combined with a set of [[Language primitive|primitives]] (at the level of [[programming language]] and [[runtime system]]) for synchronizing access to the internal properties of objects in competing [[Execution (computing)|execution]] contexts.

Above the [[Kernel (operating system)|kernel]] layer, A2 provides a set of modules providing unified abstractions for devices and services, such as [[file system]]s, [[user interface]]s, [[computer network]] connections, media [[codec]]s, etc.

== User interface ==
Bluebottle introduced a zooming user interface (ZUI), replacing the text-based interface of the original Oberon OS. The ZUI combines graphical elements with command-driven interaction. Like Oberon, though, its user interface supports a ''[[point and click]]'' [[interface metaphor]] to execute commands directly from text, similar to clicking [[hyperlink]]s in a [[web browser]].

== Reception and Adoption ==
There is limited independent coverage of A2 in mainstream computing literature. While primarily used in academic and experimental contexts, A2 and its [[Predecessors of European sovereign states|predecessors]] have been cited in publications exploring lightweight [[operating system]] design, type safety, and concurrency models.

As of 2025, A2 remains under development, primarily by ETH Zurich and affiliated contributors.
==See also==
* [[Active Oberon]]
* [[Oberon (operating system)]]
* [[Oberon (programming language)]]
* [[Oberon-2]] programming language
* [[Minimalism (computing)]]

==References==
{{Reflist}}

==External links==
{{Wikibooks|Oberon}}
{{Wikibooks|Oberon/A2}}
* [https://gitlab.inf.ethz.ch/felixf/oberon Main Project Page]
* [http://www.radiar.ch/ An application in industrial control at Radiar]
* [http://cas.inf.ethz.ch/projects/a2/repository/raw/trunk/ocp/Documentation/A2Documentation.pdf A2 user guide and applications description]
* [https://www.youtube.com/watch?v=Pe0ZdzO_urU A short movie showing a programming technique and the Bluebottle OS]
* Archived {{Official website|web.archive.org/web/20080608153232/www.ethoberon.ethz.ch}}, ETH Zürich
* Archived [https://web.archive.org/web/20080608153232/http://www.oberon.ethz.ch/language/genealogy Oberon Language Genealogy]
* Archived [https://web.archive.org/web/20130131042621/http://www.ocp.inf.ethz.ch/wiki/ Oberon Community Platform - Wiki & Forum]

{{Modula, Oberon}}
{{Wirth}}

[[Category:Free software operating systems]]
[[Category:ARM operating systems]]
[[Category:IA-32 operating systems]]
[[Category:X86-64 operating systems]]