# A2

> Bluebottle OS, AOS

**Wikidata**: [Q885978](https://www.wikidata.org/wiki/Q885978)  
**Wikipedia**: [English](https://en.wikipedia.org/wiki/A2_(operating_system))  
**Source**: https://4ort.xyz/entity/a2

## Summary  
A2, also known as Bluebottle OS or AOS, is an experimental operating system developed at ETH Zurich primarily by Niklaus Wirth. It is designed for educational purposes and research into system-level programming, emphasizing simplicity and clarity in design. Built with the Oberon language and runtime environment, A2 runs on platforms such as ARM and Cell architectures.

## Key Facts  
- **Aliases**: Bluebottle OS, AOS  
- **Developer(s)**: Niklaus Wirth, ETH Zurich  
- **License**: BSD-style license  
- **Platforms**: ARM architecture, Cell processor  
- **Instance of**: Operating system  
- **Source code repository**: [https://gitlab.inf.ethz.ch/felixf/oberon](https://gitlab.inf.ethz.ch/felixf/oberon)  
- **Website**: [http://www.ocp.inf.ethz.ch/wiki/OCP/Home](http://www.ocp.inf.ethz.ch/wiki/OCP/Home)  
- **Different from**: A2 (separate entity listed under same name in some contexts)  
- **Wikipedia languages**: German, English, Russian, Ukrainian  
- **Copyright status**: Copyrighted  

## FAQs  
### Q: What is A2 used for?  
A: A2 is primarily used for education and research in systems programming. It demonstrates clean architectural principles and efficient implementation techniques within a minimalistic operating system framework.

### Q: Who created A2?  
A: A2 was developed by Niklaus Wirth, a renowned Swiss computer scientist, along with contributions from ETH Zurich.

### Q: Is A2 open-source?  
A: Yes, A2's source code is publicly available under a BSD-style license via its official GitLab repository hosted by ETH Zurich.

## Why It Matters  
A2 represents a continuation of Niklaus Wirth’s legacy in designing elegant and minimalist computing systems. As part of the broader Oberon family, it emphasizes conceptual clarity over complexity, making it valuable for teaching foundational concepts in operating systems and systems programming. Its modular structure and use of high-level abstractions provide insights into alternative approaches to traditional OS development. By focusing on correctness and maintainability, A2 serves as both a practical tool for experimentation and a pedagogical resource that challenges mainstream assumptions about system software architecture.

## Notable For  
- Designed entirely in the Oberon programming language ecosystem  
- Emphasis on simplicity and modularity suitable for educational environments  
- Runs efficiently on embedded and specialized hardware like ARM and Cell processors  
- Reflects the design philosophy of Niklaus Wirth, known for Pascal and Modula-2  
- Available under a permissive BSD-style license encouraging reuse and modification  

## Body  

### Overview  
A2, alternatively referred to as Bluebottle OS or AOS, is an operating system developed at ETH Zurich under the guidance of Niklaus Wirth. The project builds upon earlier work in the Oberon system series and focuses on providing a clear, understandable model of how modern operating systems can function without unnecessary complexity.

### Development & Creator  
The primary architect behind A2 is Niklaus Wirth, a distinguished Swiss computer scientist born February 15, 1934, who passed away in 2024. He was instrumental in developing several influential programming languages including Pascal, Modula-2, and Oberon. At ETH Zurich, he led efforts toward creating lightweight, comprehensible systems software—culminating in projects like A2.

### Technical Characteristics  
A2 is built using the Oberon language and runtime system. This choice allows for tight integration between application code and system services while maintaining strong abstraction boundaries. The kernel and core components are written in a way that supports direct execution on low-level hardware platforms.

#### Supported Platforms:
- ARM architecture
- Cell processor

These targets reflect A2's orientation towards embedded systems and high-performance computing niches where control over system behavior is essential.

### Licensing & Availability  
The A2 operating system is distributed under a BSD-style license, which permits broad usage, modification, and redistribution. Source code is maintained in a public GitLab repository located at:

[https://gitlab.inf.ethz.ch/felixf/oberon](https://gitlab.inf.ethz.ch/felixf/oberon)

This openness facilitates academic study and collaborative improvement.

### Documentation & Resources  
Official documentation and further information about A2 and related technologies are accessible through the project website:

[http://www.ocp.inf.ethz.ch/wiki/OCP/Home](http://www.ocp.inf.ethz.ch/wiki/OCP/Home)

Additionally, multilingual Wikipedia entries exist in German, English, Russian, and Ukrainian, supporting wider dissemination of knowledge around the system.

### Relationship to Other Systems  
While sharing lineage with other Oberon-based systems, A2 stands out due to its focus on contemporary hardware support and streamlined internal structures. It is explicitly marked as distinct from another entry labeled “A2” in certain databases, ensuring proper identification and classification.