|Part of the Microsoft Windows family|
|Initial release||October 26, 2012info][|
Windows RT is a variant of the Windows 8 operating system designed for mobile devices which utilize the ARM architecture. First unveiled as a prototype in January 2011 at the Consumer Electronics Show, the operating system was officially launched alongside Windows 8 on October 26, 2012 with the release of three Windows RT-based tablets—one of which being Microsoft's own Surface tablet. Unlike other versions of Windows, Windows RT is only available as pre-loaded software on devices specifically designed for the operating system by OEMs.
While lacking certain features and compatibility in comparison to Windows versions for Intel-compatible processors, Microsoft intended for Windows RT devices to take advantage of the ARM platform's power efficiency to allow for longer battery life, system-on-chips to allow for thinner hardware designs, the new Windows Store platform for touch-optimized apps, and to provide a "reliable" experience over time—making the entire platform more comparable to a mobile operating system. Windows RT is also distinguished by the inclusion of a special version of Office 2013 as pre-loaded software.
Windows RT was released to mixed reviews from various outlets and critics. Some felt that Windows RT devices had advantages over other mobile platforms (such as iOS or Android) due to its bundled software and the ability to use a wider variety of USB peripherals and accessories, but concerns were also raised surrounding its software compatibility limitations and how Microsoft had promoted the platform. These shortcomings contributed to poor demand for Windows RT devices, leading to concerns from OEMs surrounding the viability of the platform.
of At the 2011 Consumer Electronics Show, it was officially announced that the next version of Windows would provide support for the ARM platform. Windows division president Steven Sinofsky demonstrated an early version of the port, codenamed Windows on ARM, running on prototypes with Qualcomm Snapdragon, Texas Instruments OMAP, and Nvidia Tegra 2 chipsets. The prototypes featured working versions of Internet Explorer 9 (with DirectX support via the Tegra 2's GPU), Powerpoint and Word, along with the use of class drivers to allow printing to an Epson printer. Sinofsky felt that the shift towards system-on-chip designs were "a natural evolution of hardware that's applicable to a wide range of form factors, not just to slates", while Microsoft CEO Steve Ballmer emphasized the importance of supporting SoCs on Windows by proclaiming that the operating system would "be everywhere on every kind of device without compromise." The following year, Microsoft officially announced that this new version of Windows for ARM devices, based off Windows 8, would be known as Windows RT and officially launch in October 2012. Initial development for Windows RT took place by porting code from Windows 7; Windows Mobile smartphones were used to test early builds of the port due to a lack of readily available ARM-based tablets. Later testing was performed using a custom-designed array of rack-mounted ARM-based systems.
As with Windows 8, Windows RT introduces a new application development platform known as the Windows Runtime (WinRT); WinRT apps can be processor-independent (supporting both x86 and ARM), primarily emphasize the use of touch input (for devices such as tablets), and run within a sandboxed environment to provide additional security. The new application infrastructure was also optimized to provide a more "reliable" experience on ARM-based devices; as such, Windows RT does not provide backwards compatibility for Win32 software otherwise compatible with Windows 8. Microsoft developers indicated that existing Windows applications were not specifically optimized for reliability and energy efficiency on the ARM architecture, and that WinRT was sufficient to "provide the full expressive power required for modern software while avoiding the traps and pitfalls that can potentially reduce the overall experience for consumers." Consequentially, the lack of compatibility with Win32 software also prevents malware designed for x86 versions of Windows from running on Windows RT as well.
Windows RT incorporates changes to the Windows codebase to provide optimizations for the internal hardware of ARM devices, but a number of standards traditionally used by x86 systems are also used. UEFI firmware is used within Windows RT devices, and a software Trusted Platform Module is used to enable device encryption and the ability to prevent unauthorized software from tampering with the boot process. ACPI is also used to detect and control plug and play devices and provide power management outside the SoC. To enable wider hardware support, peripherals such as human interface devices, storage and other components that use USB and I²C connections utilize class drivers and standardized protocols. Windows Update serves as the primary update mechanism for system drivers and software on Windows RT devices.
On May 14, 2013, Microsoft officially announced that a major update to both Windows 8 and RT, known as Windows 8.1, would be released later in the year, with a public beta released at the Build Conference in June 2013.
Differences from Windows 8 
While Windows RT does share a significant amount of its code base with Windows 8, there are still some notable differences between the two platforms, primarily involving compatibility.
Included software 
Windows RT does not include Windows Media Player, in favor of other multimedia apps found in the Windows Store; on launch, these included apps for the popular video streaming service Netflix, and the in-house Xbox Music and Xbox Video services.
In addition, all Windows RT devices include Office 2013 Home & Student RT—a special version of Microsoft Office (consisting of Excel, OneNote, PowerPoint, and Word) with optimizations for ARM-based systems.  As the version of Office RT included on Windows RT devices is based on the Home & Student version, it cannot be used for "commercial, nonprofit, or revenue-generating activities" unless the organization has a volume license for Office 2013, or the user has an Office 365 subscription with commercial use rights.
Software compatibility 
The only desktop applications officially supported by Windows RT are those that come with the operating system itself (such as File Explorer, Internet Explorer, and the Office RT programs). Only WinRT apps, obtained from the Windows Store or sideloaded in enterprise environments, can be installed by users on Windows RT devices. The ability to run or port desktop applications compatible with previous versions of Windows is not offered, since Microsoft developers felt they would not be properly optimized for the platform.
Additionally, Windows RT does not support "new-experience enabled" web browsers; a special class of app used on Windows 8 that allows web browsers to bundle variants that can run in the Metro shell and integrate with other apps, but still use Win32 code like desktop programs.
Hardware compatibility 
In a presentation at Windows 8's launch event in New York City, Steven Sinofsky claimed that Windows RT would support 420 million existing hardware devices and peripherals. However, full functionality will not be available for all devices, and some devices will not be supported at all. Microsoft provides a "Compatibility Center" portal where users can search for compatibility information on devices with Windows RT; on launch, the site listed just over 30,000 devices that were compatible with the operating system.
Device management 
Windows RT does not support connecting to a domain for network logins, nor does it support using Group Policy for device management like normal versions of Windows 8. However, Exchange ActiveSync, the Windows Intune service, or System Center Configuration Manager 2012 SP1 can be used to provide some control over Windows RT devices in enterprise environments, such as the ability to apply security policies and provide a portal which can be used to sideload apps from outside the Windows Store.
Support lifecycle 
Unlike Windows 8 (which, per the company's standard practices, receives around 5 years of mainstream support), Microsoft did not announce any specific date for the end of mainstream support for Windows RT devices. However, its Surface tablet will only receive mainstream support until April 11, 2017, as it falls under its support policies for consumer hardware.
Microsoft imposes tight control on the development and production of Windows RT devices: they are designed in cooperation with the company, and must be built to strict design and hardware specifications. For quality-control reasons, only "approved" models of certain components may be used. To ensure hardware quality and limit the number of devices released upon launch, the three participating ARM chip makers were only allowed to partner with up to two PC manufacturers to develop the first "wave" of Windows RT devices as part of Microsoft's development program. Qualcomm partnered with Samsung and HP, Nvidia with Asus and Lenovo, and Texas Instruments with Toshiba. Additionally, Microsoft partnered with Nvidia to produce its own Windows RT tablet, known as the Surface RT. The Surface RT is the first ever Windows PC to be manufactured and marketed directly by Microsoft.
Toshiba and TI soon pulled out of the development program, and TI later announced that it would stop developing ARM chipsets for mobile devices entirely. HP also pulled out of the program, believing that Intel-compatible tablets were more appropriate for business use than ARM. HP was replaced by Dell as an alternate Qualcomm partner. Acer also intended to release a Windows RT device alongside its Windows 8-based products, but initially decided to delay it until the second quarter of 2013 in response to the mixed reaction to Surface. The unveiling of the Microsoft-developed tablet caught Acer by surprise, and its CEO felt that Surface could leave "a huge negative impact for the [Windows] ecosystem and other brands." Acer's president Jim Wong later reiterated its plans for Windows RT by stating that there was "no value" in the current version, and that it would wait for the first major update to the operating system (scheduled for release later in 2013) to make its decision on future Windows RT products.
The first wave of Windows RT devices included:
- Asus VivoTab RT (released October 26, 2012)
- Dell XPS 10 (released December 2012)
- Lenovo IdeaPad Yoga 11 (released December 2012)
- Microsoft Surface RT (released October 26, 2012)
- Samsung Ativ Tab (Released in United Kingdom on December 14, 2012, American and German releases cancelled)
Windows RT's launch devices received mixed reviews upon their release. Within a review of the Asus VivoTab RT by PC Advisor, its offering of a full-featured file manager (unlike other mobile operating systems) was cited as a positive aspect, but noted its incompatibility with x86 applications, and its lack of a proper default media player aside from the "shameless, in-your-face conduit to Xbox Music." AnandTech believed Windows RT was the first "legitimately useful" mobile operating system, due in part to its multi-tasking system, bundled Office programs, smooth interface performance, and "decent" support for a wider variety of USB devices in comparison to other mobile operating systems on the ARM platform. However, the Windows Store ecosystem was criticized for not having as many good applications at launch unlike its competitors (but still believed that the issues surrounding the number of apps were a non-issue "[since] you can basically assume that the marketplace will expand significantly unless somehow everyone stops buying Windows-based systems on October 26th."), slower application launch times in comparison to a recent iPad, and spotty driver support for printers.
Restrictions and compatibility limitations 
Microsoft requires certified Windows 8 hardware to be shipped with the UEFI secure boot feature enabled by default. Although other consumer electronics use similar protection measures, the requirement that Windows RT devices have secure boot permanently enabled was further criticized for harming user choice by preventing the installation of alternative operating systems such as Linux.
The requirement to obtain most software on Windows RT through the Windows Store was considered to be similar in nature to other "closed" mobile platforms such as iOS, where the App Store is the only official manner to obtain software, and only software approved by Apple can be distributed through the platform. Microsoft was also criticized by the developers of the Firefox web browser for effectively preventing the development of third-party web browsers for Windows RT (and thus forcing use of its own Internet Explorer browser) by restricting the development of desktop applications and by not providing the same APIs and exceptions available on Windows 8 to code web browsers that can run in the "Metro" shell.
"Jailbreak" exploit 
In January 2013, a privilege escalation exploit was discovered in the Windows kernel that can allow unsigned code to run under Windows RT; the exploit involved the use of a remote debugging tool (provided by Microsoft to debug WinRT apps on Windows RT devices) to execute code which changes the signing level stored in RAM to allow unsigned code to execute (by default, it is set to a level that only allows code signed by Microsoft to execute). Alongside his explanation of the exploit, the developer also included a personal appeal to Microsoft urging them to remove the restrictions on Windows RT devices, contending that their decision was not for technical reasons, and that the devices would be more valuable if this functionality were available. In a statement, a Microsoft spokesperson applauded the effort, indicating that the exploit does not pose a security threat because it requires administrative access to the device, advanced techniques, and would still require programs to be re-compiled for ARM. However, Microsoft has still indicated that the exploit would be patched in a future update.
A batch file-based tool soon surfaced on XDA Developers to assist users in the process of performing the exploit, and a variety of ported desktop applications began to emerge, such as the emulator Bochs (demonstrated by a user running Apple's x86-based Rhapsody operating system as a proof of concept, "because Windows 95 is too boring"), PuTTY, and TightVNC.
Confusion between Windows 8 and RT 
Despite Steven Sinofsky promising that these differences would be adequately addressed in advertising, Microsoft was also criticized for not properly communicating the differences between Windows 8 and RT to consumers. When pre-orders for the Surface tablet with Windows RT were opened, reports indicated the use of confusing wording alluding to the compatibility differences in promotional material online. In an investigative report by The Verge, it was also discovered that the employees at a Microsoft Store and online representatives had varying levels of knowledge in relation to the differences between Windows 8 and Windows RT; most of them incorrectly claimed that Windows RT devices could run all applications compatible with Windows 8, including desktop programs. However, in response, Microsoft stated that staff at its retail outlets would be given an average of 15 hours of training prior to the launch of Windows 8 and Windows RT to ensure consumers are able to make the correct choice for their needs.
Market relevance and response 
The need to release an ARM-compatible version of Windows has been questioned by analysts due to the recent introductions of x86-based system-on-chip designs by both Intel and AMD; such as Intel's Atom SoC codenamed "Clover Trail" (introduced prior to the release of Windows 8 and RT), and AMD's Fusion SoC codenamed "Temash" (unveiled at the 2013 Consumer Electronics Show). In the case of Clover Trail, Intel claimed that the chipset could provide battery life rivaling that of ARM devices while still running the full Windows 8 operating system. In a test conducted by PC World, Samsung's Clover Trail-based Ativ Smart PC was found to have battery life exceeding that of the Asus VivoTab RT and Microsoft Surface tablets.
Peter Bright of Ars Technica argued that Windows RT had no clear purpose, since the power advantage of ARM-based devices was "nowhere near as clear-cut as it was two years ago." While suggesting that the pre-loaded Office applications could possibly make Windows RT devices useful, Bright felt that due to the licensing restrictions imposed on them, users would be better off purchasing Office for use on an Atom tablet instead, due to its inclusion of Outlook and support for macros (which are both excluded from Office RT). The lack of quality apps available from the Windows Store available on launch has also been cited as a factor negatively impacting Windows RT, especially given that it is intended to be the only source of third-party software.
Windows RT has also been met with lukewarm reaction from manufacturers; in June 2012, Hewlett-Packard cancelled its plans to release a Windows RT tablet, stating that its customers felt Intel-based tablets were more appropriate for use in business environments. In January 2013, Samsung cancelled the American release of its Windows RT tablet, the Ativ Tab, citing the unclear positioning of the operating system, "modest" demand for Windows RT devices, plus the effort and investment required to educate consumers on the differences between Windows 8 and RT as reasons for the move. Mike Abary, senior vice president of Samsung's U.S. PC and tablet businesses, also stated that the company was unable to build the Ativ Tab to meet its target price point—considering that lower cost was intended to be a selling point for Windows RT devices. Nvidia CEO Jen-Hsun Huang expressed disappointment over the market performance of Windows RT, but called on Microsoft to continue increasing its concentration on the ARM platform, and requested that Microsoft port Outlook to Windows RT well.
By April 2013, prices had begun to drop on Windows RT tablets due to their poor demand.
See also 
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