Windows RT
Windows RT is a mobile operating system developed by Microsoft and released alongside Windows 8 on October 26, 2012. It is a version of Windows 8 or Windows 8.1 built for the 32-bit ARM architecture, designed to take advantage of the architecture's power efficiency to allow for longer battery life, to use system-on-chip designs to allow for thinner devices and to provide a "reliable" experience over time. Unlike Windows 8, Windows RT was only available as preloaded software on devices specifically designed for the operating system by original equipment manufacturers ; Microsoft launched its own hardware running it, the Surface tablet, which was followed by Surface 2, although only five models running Windows RT were released by third-party OEMs throughout its lifetime.
In comparison to other mobile operating systems, Windows RT also supported a relatively large number of existing USB peripherals and accessories and includes a version of Microsoft Office 2013 optimized for ARM devices as pre-loaded software. Some limitations it had compared to Windows 8 was that it could only execute software digitally signed by Microsoft, lacked certain developer-oriented features, and could not run applications designed for x86 processors, which were the main platform for Windows at the time. Windows RT 8.1 was released in 2013 as a free upgrade, featuring a number of improvements.
It received mixed reviews at launch, while critics and analysts deemed it to be commercially unsuccessful. It was criticized for its poor software ecosystem, citing the early stage of Windows Store and its incompatibility with existing Windows software. Some felt Windows RT devices had advantages over other mobile platforms because of its bundled software, and the ability to use a wider variety of USB peripherals and accessories.
Improvements to Intel's mobile processors, along with a decision by Microsoft to remove OEM license fees for Windows on devices with screens smaller than 9 inches, spurred a market for low-end Wintel tablets running the full Windows 8 platform, giving battery life and functionality that met or exceeded that of Windows RT devices; these effectively cannibalized Windows RT sales, and was a reason why Microsoft suffered a US$900 million loss in July 2013. With the release of Surface 3 in 2015, the Surface line switched to Intel processors. In 2018, Microsoft would partner with Qualcomm on launching an ARM version of Windows 10; unlike Windows RT, the OS would support running x86 software via emulation.
History
At the 2011 Consumer Electronics Show, it was officially announced that the next version of Windows would provide support for system-on-chip implementations based on the ARM architecture. Steven Sinofsky, then Windows division president, demonstrated an early version of a Windows port for the architecture, codenamed Windows on ARM, running on prototypes with Qualcomm Snapdragon, Texas Instruments OMAP, and Nvidia Tegra 2 chips. The prototypes featured working versions of Internet Explorer 9, PowerPoint and Word, along with the use of class drivers to allow printing to an Epson printer. Sinofsky felt that the shift towards SoC 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."Initial development on WoA took place by porting code from Windows 7; Windows Mobile smartphones were used to test early builds of WoA because of lack of readily available ARM-based tablets. Later testing was performed using a custom-designed array of rack-mounted ARM-based systems. Changes to the Windows codebase were made to optimize the OS for the internal hardware of ARM devices, but a number of technical standards traditionally used by x86 systems are also used. WoA devices would use UEFI firmware and have a software-based Trusted Platform Module to support device encryption and UEFI Secure Boot. 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 use class drivers and standardized protocols. Windows Update serves as the mechanism for updating all system drivers, software, and firmware.
Microsoft showcased other aspects of the new operating system, to be known as Windows 8, during subsequent presentations. Among these changes was the introduction of Windows Runtime. Software developed using this new architecture could be processor-independent, would emphasize the use of touch input, would run within a sandboxed environment to provide additional security, and be distributed through Windows Store—a store similar to services such as the App Store and Google Play. WinRT was also optimized to provide a more "reliable" experience on ARM-based devices; as such, backward compatibility for Win32 software otherwise compatible with older versions of Windows was intentionally excluded from Windows on ARM. Windows developers indicated that existing Windows applications were not specifically optimized for reliability and energy efficiency on the ARM architecture and that WinRT was sufficient for providing "full expressive power" for applications, "while avoiding the traps and pitfalls that can potentially reduce the overall experience for consumers." Consequentially, this lack of backward compatibility would also prevent existing malware from running on the operating system.
On April 16, 2012, Microsoft announced that Windows on ARM would be officially branded as Windows RT. Microsoft did not explicitly indicate what the "RT" in the operating system's name referred to, but it was believed to refer to the WinRT architecture. Steven Sinofsky stated that Microsoft would ensure the differences between Windows RT and 8 were adequately addressed in advertising. However, reports found that promotional web pages for the Microsoft Surface tablet had contained confusing wording alluding to the compatibility differences and that Microsoft Store representatives were providing inconsistent and sometimes incorrect information about Windows RT. In response, Microsoft stated that Microsoft Store staff members would be given an average of 15 hours of training prior to the launch of Windows 8 and Windows RT to ensure that consumers were able to make the correct choice for their needs. The first Windows RT devices were officially released alongside Windows 8 on October 26, 2012.
Windows 8.1, an upgrade for Windows 8 and RT, was released in Windows Store on October 17, 2013, containing a number of improvements to the operating system's interface and functionality. For Windows RT devices, the update also adds Outlook to the included Office RT suite. The update was temporarily recalled by Microsoft shortly after its release, following reports that some Surface users had encountered a rare bug which corrupted their device's Boot Configuration Data during installation, resulting in an error on startup. On October 21, 2013, Microsoft released recovery media and instructions which could be used to repair the device and restored access to Windows 8.1 the next day.
Comparison to Windows 8
While Windows RT functions similarly to Windows 8, there are still some notable differences, primarily involving software and hardware compatibility. Julie Larson-Green, then executive vice president of the Devices and Studios group at Microsoft, explained that Windows RT was ultimately designed to provide a "closed, turnkey" user experience, "where it doesn't have all the flexibility of Windows, but it has the power of Office and then all the new style applications. So you could give it to your kid and he's not going to load it up with a bunch of toolbars accidentally out of Internet Explorer and then come to you later and say, 'why am I getting all these pop-ups?' It just isn't capable of doing that by design."Included software
Windows RT does not include Windows Media Player, in favor of other multimedia apps found on Windows Store; devices are pre-loaded with the in-house Xbox Music and Xbox Video apps.All Windows RT devices include Office 2013 Home & Student RT—a version of Microsoft Office that is optimized for ARM 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. For compatibility and security reasons, certain advanced features, such as Visual Basic macros, are not available in Office RT.
Windows RT also includes a BitLocker-based device encryption system, which passively encrypts a user's data once they sign in with a Microsoft account.