Windows Vista

Windows Vista (codenamed Longhorn) is a major release of Microsoft Windows released to manufacturing on 8 November 2006 and general availability on 30 January 2007. It is the seventh operating system in the Windows NT operating system line, succeeding Windows XP and preceding Windows 7. It had one of the longest development periods in Microsoft's history starting in May 2001 and continuing until November 2006, since its development was reset in mid-2004.

This is the first version of Windows that lacks support for systems without ACPI, as it will display a black screen with error messages when launched.

Development
Planning for the Longhorn project started in earnest in May 2001, originally intended as a bridging release between Whistler and the later version of Windows codenamed Blackcomb (reference to the bar between two mountains in British Columbia, Canada). As development progressed, many features slated for Blackcomb became part of Longhorn, and employees jumped ship from other parts of the company, turning into a major version rather than the minor version it was initially planned as. After an initially quiet development cycle, the first build to leak publicly was build 3683, which contained a new theme called Plex, as well as the foundations for WinFS, a subsystem that aimed to bring benefits of relational databases to filesystem storage, and Avalon, a new vector-based user interface framework.

As development progressed before the reset, Longhorn became a heavily bloated and unstable piece of vaporware, with release dates being pushed back on several occasions. Many components were extended using the still relatively new .NET Framework and Managed C++. Stability increasingly became an issue as development progressed, and very few builds were publicly released as a result. Only two builds were distributed at conferences and to developers: build 4051 and build 4074. The last confirmed build prior to the development reset is build 4093.

On 19 August 2004, the same day as the compilation of 4093, Microsoft reset the development of Windows Longhorn and started fresh using Windows Server 2003 Service Pack 1 as a codebase, starting the Omega-13 period. Immediate post-reset builds were primarily focused on reintegrating features from the pre-reset builds while maintaining stability. Most of these builds are similar to Windows XP in the overall look and feel. Few builds from this stage of development have been released, officially or otherwise. Development of Longhorn continued, albeit many features originally slated for inclusion were delayed or dropped to produce a more realistic set of goals for the OS. Examples of said features include WinFS and Castles.

In April 2005, build 5048 was released to testers on WinHEC 2005. This build showed the progress made since the reset and also proved much more stable than previous builds, despite some concern from insiders of the era. The first leaked build after development reset was 5098. Build 5112 (Beta 1) was released to the public soon afterward in July and showcased an early version of the Aero interface, as well as many stability improvements over Windows XP. Later that year and the next year, many builds were released to testers in a public beta program, with builds dubbed as "Community Technology Previews" (CTPs). The final build that was pushed out to public preview testers was Release Candidate 2 (build 5744). The RTM build was build 6000.16386, compiled on 1 November 2006 and released to manufacturing on 8 November 2006. Windows Vista finally reached General Availability on 30 January 2007.

Naming
Several product names for the Longhorn project were presented to Microsoft in the lead-up to the final release of the operating system; the final name of the operating system, Windows Vista, was officially unveiled on 22 July 2005. Greg Sullivan informed Paul Thurrott about how the name Vista focused around the premise of wanting "the PC to adapt you" and aimed in "bringing clarity to your world"; the operating system was intended to be marketed with the terms "Connected, Clear and Confident". Microsoft vice president Jim Allchin expressed his enthusiasm for the product name, stating that it created the "right imagery for the new product capabilities".

The earliest known build to use the final name is build 5112, and the final build to have any leftovers of the Longhorn codename is build 5284.

Hardware compatibility
Intel CPUs whose microarchitectures are based on Haswell or later are not supported on Windows Vista. Numerous issues relating to certain services or applications failing to start on the affected CPUs have been reported by various users, with extreme cases often leading to potential bugchecks. The KB4493471 update contains a new version of the HAL (hardware abstraction layer) that fixes most of these issues.

Windows XP, earlier operating systems and x86 versions of Windows Vista are not affected by the aforementioned problems.

Main changes
The new Aero user interface has been introduced, which included large design changes to many of the built-in apps. Microsoft also encouraged third party developers to make their applications consistent with Aero, with the company for the first time producing a definite set of design guidelines that included advice ranging from icon design to text wording. Compared to previous versions, Aero icons are more skeuomorphic and realistic in design, as well as scale better at higher zoom levels due to larger icon sizes being supported.

An important aspect of the user interface was the hardware-accelerated Windows Aero theme. This was made possible by the new Desktop Window Manager, a compositing window manager that works hand in hand with the also new Windows Display Driver Model (WDDM). The compositing nature of DWM allows for eye candy such as Aero Glass or Flip 3D, but also prevents various rendering glitches that were common for previous versions of Windows. The exact appearance of Aero Glass can be further customized by toggling the transparency or changing the frame's color, which is not possible for themes that are not composited. Live taskbar thumbnails have also been introduced, which show the preview of a window when hovered over its button in the taskbar.

For systems that relied on older drivers made for Windows XP, Vista also included the Windows Basic style, which used the older XP-style theme engine, as well as still included the Windows Classic theme that disabled theming altogether.

The licensing subsystem has been completely rewritten in Windows Vista. This allowed Microsoft to define licensing restrictions for each SKU more easily and systemically using product policies, rather than hardcoding them in the kernel or using hooks for core system components. Product policies are used to limit the maximum amount of RAM, number of processors, as well as the availability of user interface options such as the Aero theme or transparency.

Networking stack has also been overhauled in Windows Vista. The new stack model includes IPv6 support, completely overhauled IPv4 and TCP/IP stacks and improves peer-to-peer connectivity.

Other notable changes include the introduction of Internet Explorer 7, a newly redesigned version of Windows Media Center, Windows Media Player 11, Windows Sidebar and Gadgets, redesigned games, Windows Boot Manager and more.

Editions
Windows Vista was shipped in a number of editions. Unlike Windows XP, there were no special editions for Media Center, 64-bit capabilities and Tablet PCs since these features were included in at least one of the consumer editions. Windows Vista also did not have a separate componentized embedded version, as Microsoft instead planned to release Windows Embedded 2009, which is based on Windows XP. Although the Business and Ultimate editions were also available for licensing on embedded devices (namely Windows Vista Business for Embedded Systems and Windows Vista Ultimate for Embedded Systems) as a part of Windows Embedded Enterprise product line, they are essentially the same as the base editions available on retail.


 * Starter: This edition is intended for emerging markets and low-cost PCs. Like its predecessor, the three-program limit was included, and a maximum limitation of 1GB installable RAM is imposed. Other software restrictions were applied as well; hence, this version isn't available in 64-bit. This edition is the only edition of Vista that does not have Desktop Window Manager and Windows HotStart enabled. Only Windows XP Starter Edition can be upgraded to Windows Vista Starter.
 * Home Basic: Found in low-cost to mid-end computers, this version of Windows Vista does not feature complete Aero (though it includes DWM functionality) and hence does not have effects like transparency and Flip 3D. Windows Media Center, Windows DVD Maker and various backup features are also not present in this edition. And unlike the Starter edition, it does not have the hardware and 3-program maximum limitations.
 * Home Premium: The consumer version of Windows Vista. This version includes full Aero functionality, Windows Media Center, Premium Games (e.g.: Inkball, Purble Place) and various WMP11 audio decoders. However, it lacks the BitLocker and Complete PC Backup functionalities.
 * Business: A business-oriented version of Windows Vista, it contains several features like full RDP (client/host) capability, Group Policy, domain joinability and Windows Fax and Scan. However, Windows Media Center and Parental Controls are not included, and Premium Games are disabled by default. For the embedded market, there's a sub-edition called "Windows Vista Business for Embedded Systems".
 * Enterprise: A business-oriented variant of Windows Vista. It is similar to Ultimate, but does not include consumer-specific features such as Windows Media Center and Parental Controls. Rather, it includes enterprise-specific tools, Windows Fax and Scan and Windows Services for UNIX. This edition was only available to customers who participated in the Microsoft Software Assurance program.
 * Ultimate: The high-end variant of Windows Vista. It is a merger of the features included with Windows Vista Home Premium and Business. BitLocker is included in this version. This edition also allows the user to install "Windows Ultimate Extras", which is a set of addons that include games, sound schemes, animated wallpapers (referred to as Windows DreamScene), BitLocker and additional Windows Marketplace enhancements. A sub-edition of Vista Ultimate called "Windows Vista (PRODUCT)RED" was related to the "Product Red" campaign, which aids in supporting global funding for research on diseases such as AIDS, tuberculosis, and malaria. This version includes extra (PRODUCT)RED-themed wallpapers, gadgets and a special theme.

Misattributed system sounds
The widespread sound scheme often attributed to Longhorn was never included in any official build, and originates from a Samsung-produced theme for Windows XP from 2003. The Windows XP sounds remain and are used in all pre-reset builds, with a few being swapped with Vista sounds between builds 5466 and 5840.16384.

The alleged Windows Vista Beta 1 startup sound is actually  used in the Speech Recognition tutorial in build 5308.6 and onwards. Likewise, an alternative interpretation of the final startup sound that is sometimes labeled as the Windows Vista Beta 2 startup sound is actually a jingle used in Vista Beta 2 Help video outros.

Development reset
These builds are also referred to as Omega-13 builds.