Windows Sienna

Windows Sienna was designed to be a modification by Microsoft to Windows 2000 that extended the kernel, allowing it to run more recent Windows applications. This was developed around 1999 and released on March 2, 2003. During the beta stage, Microsoft was making a way to remove the Y2K bug. The reason why it was so delayed until the release to the consumers is that Microsoft had a bug during the Preliminary Testing. This took a lot of time and also modified some parts of the OS.

Mainstream support ended on August 6, 2012 and extended support ended on August 30, 2015.

HISTORY OF WINDOWS SIENNA
 * October 2, 1999 - First Pre-Alpha build (NT 5.0) (Build 6233.devms)
 * October 10, 1999 - First Developer Release (based on 2000 prototype) (Build 6243.devpubms1)
 * October 18, 1999 - Second Pre-Alpha Build (2000 Beta) (Build 6253.devNT)
 * October 20, 1999 - First Alpha Build (also as a Development Release) (Build 6263.devmspub1.2)
 * October 23, 1999 - Beta 1 (Build 6214)
 * October 25, 1999 - Stability Testing (based on SecureNT) (Build SEc6214)
 * October 31, 1999 - Beta 2 (Build 6224)
 * November 2, 1999 - Beta 3 (Millennium NT Edition Prototype) (Build 6235)
 * November 10, 1999- Beta 4 (Sienna) (Build 6245)
 * November 23, 1999 - Sienna Public Testing (Build 6255)
 * November 30, 1999 - Sienna Business Test (Build 6265)
 * December 2, 1999 - Sienna RC1 (Build 6216)
 * December 10, 1999 - Sienna RC2 (Build 6226)
 * December 20, 1999 - Sienna RC3 (Build 6236)
 * December 30, 1999 - Preliminary Testing for Consumers
 * January 5, 2000 - Preliminary Testing for Businesses
 * January 10, 2000 - Compatibility Testing
 * January 23, 2000 - Security Test
 * January 30, 2000 - Emergency ReTest (Emergency Build)
 * September 23, 2001 - Preliminary Testing for Consumers 2
 * September 30, 2001 - Preliminary Testing for Businesses 2
 * February 20, 2002 - Sienna RC1 Rev 1
 * February 28, 2002 - Sienna RC2 Rev 1
 * March 30, 2002 - Sienna RC3 Rev 1
 * April 19, 2002 - Sienna RC4
 * May 2, 2002 - Sienna RC5
 * August 2, 2002 - Security and Stability Test
 * December 30, 2002 - Test RTM
 * February 27, 2003 - RTM (Build 6600)

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