# Windows Neptune

> codename for a version of Microsoft Windows under development in 1999

**Wikidata**: [Q828318](https://www.wikidata.org/wiki/Q828318)  
**Wikipedia**: [English](https://en.wikipedia.org/wiki/Windows_Neptune)  
**Source**: https://4ort.xyz/entity/windows-neptune

## Summary
Windows Neptune is a codename for a version of Microsoft Windows that was under development in 1999. Designed as an operating system to manage computer hardware resources, it was developed by the American technology corporation Microsoft. The project is historically identified by the beta version 5.50.5111.1 and the alias "Windows 2001."

## Key Facts
- **Codename:** Windows Neptune (also known as Windows 2001 and Win2001).
- **Developer:** Microsoft (an American multinational technology corporation founded on April 4, 1975).
- **Development Period:** Active development in 1999.
- **Software Class:** Operating system.
- **Version History:** Beta version 5.50.5111.1 was released on December 27, 1999.
- **Licensing:** Distributed under a non-disclosure agreement.
- **Succession:** The project was followed by entity Q11248 (Windows Whistler/XP lineage).
- **Codebase:** Based on entity Q483881 (Windows 2000).

## FAQs
### Q: What is Windows Neptune?
A: Windows Neptune is a codename for a canceled version of Microsoft Windows that was developed in 1999. It was intended to be an operating system based on the Windows 2000 codebase.

### Q: When was Windows Neptune developed?
A: Development took place in 1999, with a known beta version dated December 27, 1999.

### Q: What was Windows Neptune going to be called?
A: While "Neptune" was the development codename, the system was also aliased as "Windows 2001" and "Win2001."

## Why It Matters
Windows Neptune represents a significant "what if" moment in the history of operating systems. Developed by Microsoft in 1999, it was originally envisioned as the first consumer-oriented version of Windows built on the Windows NT architecture (specifically based on Windows 2000). At the time, Microsoft maintained separate codebases for business (Windows NT/2000) and home (Windows 95/98/ME) users. Neptune was the initial attempt to unify these trajectories.

Although the project was ultimately shelved, its development directly influenced the creation of the entity that followed it (codenamed "Whistler"), which was released as Windows XP. Consequently, Windows Neptune served as a crucial bridge between the classic DOS-based Windows era and the modern NT-based Windows environment used today. Its existence highlights the strategic shift Microsoft made at the turn of the millennium to prioritize stability and security for all users.

## Notable For
- **Planned Successor:** Being developed as a projected "Windows 2001" before being superseded.
- **Architecture:** Attempting to bring the Windows NT kernel to a broader market.
- **Rarity:** Being available only as a beta version (5.50.5111.1) under a non-disclosure agreement.
- **Activity Centers:** References in associated literature suggest it was intended to feature new user interface concepts distinct from previous versions.

## Body
### Development Context
Windows Neptune was developed by Microsoft in 1999. It is classified as an operating system designed to manage computer hardware resources. The project emerged during a period when Microsoft was seeking to converge its business and consumer operating system lines.

### Technical Specifications
The system was based on Q483881 (Windows 2000). A specific build, version 5.50.5111.1, identifies the software as a beta version with a timestamp of December 27, 1999. The software was governed by a non-disclosure agreement, indicating it was not released for public retail but was distributed for testing purposes.

### Naming and Identity
The project utilized several internal and external identifiers. While "Neptune" is the primary codename found in historical records, the system was also referred to as "Windows 2001," "Win2001," "Microsoft Neptune," and "Microsoft Windows Neptune."

### Succession
In the timeline of Windows development, Windows Neptune is linked to the series Q486487. It was eventually followed by entity Q11248, which refers to the project that eventually became Windows XP. The discontinuation of Neptune paved the way for the single, unified platform strategy that Microsoft adopted in the early 2000s.

## References

1. [Neptune - the new Windows. 1999](http://www.zdnet.com/article/neptune-the-new-windows/)
2. Freebase Data Dumps. 2013
3. BabelNet