Windows Codename "Longhorn" was the planned successor to Windows XP. This project never released, but rather its development was reset, creating the new project Longhorn/Omega-13, which eventually became Windows Vista. The earliest builds after the reset were also known as "Codename Longhorn", causing some confusion. "Longhorn" went through many stages of development. Development started as a minor revision to Windows XP, known as "Whistler +1". Longhorn was originally intended as an interim release, a bridge between Windows XP (Whistler), and a major new version known as "Blackcomb", which eventually became Windows 7. Over time, many features slated for Blackcomb became part of Longhorn, and employees jumped ship from other parts of the company. Longhorn became a bloated, unstable piece of vapourware. The first build to leak publicly was build 3683, which contained a new theme, and also the foundations for WinFS, and Avalon, which eventually became the Windows Presentation Framework. "Longhorn" was originally intended to be an interim release, but picked up many features slated for it's successor. Stability increasingly became an issue as development progressed, and few builds were publicly released as a result. In fact, the only build to become officially available from Microsoft to the wider world was build 4074. The last known confirmed build from before the development reset is build 4093.
One of the original - and largest - changes is that, with "Longhorn," the .NET Framework would be integrated into the core Windows platform, deprecating the traditional Win32 API. During development, portions of the operating system were rewritten, causing memory leaks and instability, particularly in Windows Explorer.
Contrary to popular belief, most of the early builds of "Longhorn" are not based on Windows XP, but Windows Server 2003 (Build 3663) Release Candidate code.
Build Labs[]
These Buildtag are included for Build Labs, they are included some following like this:
- Lab01: Base
- Lab02: Networking
- Lab03: Server
- Lab04: Management
- Lab06: Desktop
- Lab07: IIS/COM+
Notice that there is no Lab05. This fifth lab is the ‘main branch’. As you can see, each lab has a different function or task. Take for example the sixth lab, better known as the shell or desktop lab. This lab in particular is an interesting one since all of the user interface work comes from this lab. The labs above are not exclusive to Longhorn, but were already were not only seen during Longhorn development, but also during the development of Windows XP and Server 2003.
Builds[]
Along these Builds, it was Leaked Screenshot for Build 3663, Which means its very old Build.
There was included Prototypes Longhorn Screenshot, you can see Windows:Longhorn/Prototypes.
A Fake Build for Longhorn 3551, it was Confirmed to be fake for using NT Custom Kernel.
Milestone 1[]
3561.Lab01_N(storbuild).011003-1326 3562.Lab03_N.011002-1958 3589.Lab01_N(johnstra).011110-2230 3590.Lab01_N.011118-2000 3593.Lab01_N(daved).011129-1917 3595.Lab01_N.011203-0927 3595.Lab02_N(ntvbl02).020107-1351 3609.Lab01_N.020211-2000 3630.Lab03_dev(yasuho).??????-???? 3631.Lab03_dev(skatari).020509-1043 3635.Lab01_N.020517-1743 3637.Lab01_N.020522-2000 3646.Lab01_N(portbld).020612-1346 
3653.Lab04_dev.020728-1357 3656.Lab02_N.021208-1102 Milestone 2[]
3661.Lab01_N(ianserv).020709-0927 3663.Lab01_N.020724-2000 3673.Lab01_N(henrygab).020621-1446 Milestone 3[]
3728.dnsrv_dev(sergueik).??????-???? 3750.private_lab06_dev_ux(thomasj).021128-1402 3883.?.021120-???? 3940.?.021205-???? (The timestamps and build string is not known exactly for these last two builds).
Milestone 4[]
4000.main.02????-???? 4002.Lab04_N(yongqu).021218-1747 4003.Lab01_N(forrestf).030116-1035 4006.Lab01_N.030209-2000 4008.Lab01_N(briangu).030220-0837 4013.main.030320-1058 Milestone 5[]
4026.main.030602-???? Milestone 6[]
4040.Lab04_N.030828-1910 Milestone 7[]
4050.private/lab06_demo.031018-2015 4050.private/lab06_demo.031019-1809 4057.private/lab06_dev_ux.031107-1900 4074.idx02.040425-1535
Development Reset[]
- After the compilation of build 4093, the development of Longhorn was reset, mainly because of the instability of the current Longhorn branch. At about 9PM, on the same day as the compilation of 4093, Microsoft stopped development of Windows Longhorn, and started fresh using Windows Server 2003 Service Pack 1 as a codebase. Development of Longhorn continued, albeit many features originally slated for inclusion were delayed or dropped to provide a more realistic operating system. Examples of this include WinFS, and what would become Windows Powershell.
- See Windows Vista for information on the post-reset (Omega-13) builds.