Windows Neptune

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Windows Neptune
Windows Neptune Logo.png
Microsoft Windows Neptune
Preliminary name
Kernel version NT 5.50
CPU architecture x86
Release date Canceled; never released
Support end Canceled; never supported
Preceded by Windows 2000 / Windows ME
Succeeded by Windows XP

Microsoft Windows "Neptune" (internally at Microsoft also known as NepTune) was planned to become the successor of the Windows 2000 family as well as the first consumer version of Windows under the NT kernel. It was under development in 1999, until it was canceled, along with Odyssey to give way for Whistler, which would be released as Windows XP in 2001. XP included a new login screen, help center and user accounts panel originally envisioned for Neptune. However, Activity Centers were eventually dropped. As stated in confidential Microsoft documents, Neptune was to be released in Q1 2000, planned to have 64-bit edition (referred to as "NT64") for the upcoming Intel Itanium processor, "Solar Coaster" (Unix Services for NT), Internet Explorer 6 (which was also in development at the time) and some Anti-Piracy features. There is evidence that five service packs were planned for Neptune.

A successor called "Triton" was mistaken as a service pack, but as shown in Antitrust documents, it was actually a successor to Neptune which would bring minor updates and enhancements.

Original roadmap

The following planned release dates come from PX07297.

  • RTM: March 2000
  • SP1: May 2000
  • SP2: September 2000
  • SP3: January 2001
  • SP4: July 2001
  • SP5: March 2002

Other Neptune SKUs

Microsoft Anti-trust documents from Neptune era indicate that Neptune was to have not only one, but several editions, namely "Entry-Level", "Standard" and "High-End", which could translate into these modern SKUs: "Starter", "Home" and "Professional / Server". It is unknown what these editions would actually become, if Neptune was ever released.

There are also several strings in file USETUP.EXE from Neptune build 5111.1 that clearly mention "Neptune Server". These references could be leftovers from Windows 2000, if all "2000" strings were simply replaced with "Neptune" during the rebranding process.


NOTE: Only Build 5.5.5111.1 was ever leaked, the rest of the builds were mentioned in file versions in various Windows Me builds and Builds 5.5.5118.1, 5.5.5119.1, and 5.5.5120.1 were mentioned in early Windows XP builds.

  • No information available
  • Existence doubtful
  • Information or pictures available
  • Leaked or released

See also

BetaArchive forums

External links