Windows Longhorn build 4001

6.0.4001.main.021204-1515
	Build of Windows Longhorn
OS family	Windows NT
Version number	6.0
Build number	4001
Architecture	x86
Build lab	main
Compiled on	2002-12-04
Expiration date
Timebomb	2003-11-30 (+361 days)
SKUs
	Professional
Product key
	CKY24-Q8QRH-X3KMR-C6BCY-T847Y
About dialog

Windows Longhorn build 4001 is the first Milestone 4 build of Windows Longhorn. This build was first found from screenshots that were shown by Dr. Nicholas Rush at YouArePwned's "Yet Another Longhorn Board", and by user bashar2000 on the BetaArchive forums.^[1] It was eventually uploaded to the aforementioned website on 15 January 2013.^[2]

While some features such as the Desktop Compositing Engine and Start Page are mostly retained from build 3718, it notably contains a new image-based setup procedure. This build also features the old M3 background, where it would be later replaced in build 4002.

The build number jumped to 4000 to distinguish it from Windows Server 2003 builds, which had moved from the main branch to the dnsrv branch, meaning that the final build lab had transitioned from Windows Server 2003 work to Longhorn work. This is the first known main branch build of Longhorn.

New features[edit | edit source]

OOBE[edit | edit source]

This build contains a new OOBE that replaced the Windows XP OOBE used in previous builds. The OOBE in this build only asks for account names to create (these will be Administrator accounts) and then finishes.

WIM installation[edit | edit source]

This build is among one of the first builds to use a new WIM-based setup routine, one of the first radical departures from the previous Windows NT codebase. The WIM-based setup routine works by having all of the setup files stored within a single WIM disk image, INSTALL.WIM. When the installation media is booted directly, the WinPE (Windows Preinstallation Environment) loads into the graphical user interface itself. After it images the WIM file to the system partition, the system reboots to finish the setup by installing the hardware and running the OOBE. Microsoft stated that their goal with this routine was to allow installations of Windows to finish in as little as 15 minutes.^[3]

While the installation is basic (using the Avalon interface) and lacks partitioning, it is capable of detecting hardware (including the CPU). As a result, it cannot be installed on processors older than a Pentium III, alongside a few virtual CPUs like the default emulated QEMU processor. The processor requirement would be removed in all subsequent pre-reset builds for unknown reasons.

Also, as the ability to upgrade from a previous build was not implemented at this time, the user only can clean install this build.

Bugs and quirks[edit | edit source]

Installation[edit | edit source]

Despite not being compiled in evaluation mode, it can boot on the current date. But many drivers aren't installed by default during the hardware portion of setup if you install this build on the current date and have to be installed manually.
As this build's setup cannot partition the drive, it is required to partition the drive before installation via the diskpart command.
The setup doesn't ask for the username, organization information, and time zone, so the default username of "Windows User" without an organization is used in place. Alongside, the time zone defaults to the Pacific Time Zone.
To install or run this build in VMware Workstation, the hardware compatibility must be set to version 9.0 or earlier.
On some machines, the WinPE part of setup either crashes or will throw an Avalon error. If this occurs, the machine is not compatible with this build.
- This also applies to 86Box, even with the processor set to VIA Cyrix III, the only processor on the emulator which gets past through CPU detection.

Taskbar[edit | edit source]

An interesting quirk with the New Taskbar application is that buttons appear to not be centered.

Desktop Compositing Engine[edit | edit source]

When Desktop Composition Engine is enabled, it renders the graphics on the hardware layer, while the software layer is rendered as black or leftover data, which means that attempting to use software capturing methods (such as Print Screen) will not produce the screen correctly. Most hypervisors only renders the software layer, usually resulting in a black screen upon starting DCE.

MyTVApp[edit | edit source]

MyTVApp crashes when it opens.

Media Center[edit | edit source]

Due to the new WIM setup method, components related to the Media Center application cannot be installed on this build. It is still possible to trigger the edition change by attempting to install Media Center and then rebooting.