Welcome to Browser Wars 2.0: Mozilla is warning that only Internet Explorer will have access to advanced system functionality in Windows RT (formerly known as Windows on ARM), thus effectively blocking rival Web browsers such as Mozilla\'s Firefox or Google Chrome from using the tablet-friendly new operating system. \"Unfortunately, the upcoming release of Windows for the ARM processor architecture and Microsoft\'s browser practices regarding Windows 8 Metro signal an unwelcome return to the digital dark ages where users and developers didn\'t have browser choices,\" said Harvey Anderson, general counsel for Mozilla, in a blog post. Windows RT (for runtime) is a version of the new Windows 8 operating system designed for devices with an ARM chip. Windows RT will ship with a minimal set of included applications, including Microsoft Word, Excel, PowerPoint, and OneNote, and then only run applications procured from Microsoft or via the Windows Store. A key feature of the operating system will be the Metro interface which is designed to be friendly with touch screens, and which borrows heavily from the Windows Phone 7 interface. Anderson, however, is accusing Microsoft of purposefully blocking rival browsers from the \"Windows Classic\" environment, which allows applications built to run in non-ARM environments to work on Windows RT, even though they\'re not compatible with the Metro touch-screen interface. \"By allowing only IE to perform the advanced functions of a modern Web browser, third-party browsers are effectively excluded from the platform. This matters for users of today\'s tablets and tomorrow\'s PCs. While ARM chipsets may be primarily built into phones and tablets today, in the future ARM will be significant on the PC hardware platform as well,\" said Anderson. Anderson suggested that preventing rival browsers from accessing the functionality might \"have antitrust implications\" for Microsoft, based on its 2002 settlement with the Justice Department, which required that it ensure its products would interoperate with products from rivals. He also suggested the move would harm innovation. \"These environments currently have intense browser competition that benefits both users and developers,\" he said. \"When you expand the view of the PC to cover a much wider range of form factors and designs as Microsoft and others forecast, it\'s easy to imagine Windows running on ARM in laptops, tablets, phones, and a whole range of devices. That means users will only have one browser choice whenever there\'s a Windows ARM environment.\" Microsoft is definitely eying new form factors with Windows RT. Microsoft\'s Steven Sinofsky said in a February 2012 blog post that the operating system was being designed to create \"super thin and light PCs, with great battery life, and high-quality engineering providing a great experience with apps and services that are Designed for Windows 8.\" To do that, Sinofsky also said that many components of the operating system had been redesigned from the ground up, and suggested that Windows RT--which won\'t include an emulator for running 32-bit Windows 7 software--wouldn\'t be suitable for everyone. \"If you need to run existing x86/64 software, then you will be best served with Windows 8 on x86/64. If you\'re already considering a non-Windows device, then we think [Windows on ARM] will be an even better alternative when you consider the potential of form factors, peripherals, Windows Store apps (and developer platform), and Office applications as well as a broad set of intrinsic Windows capabilities,\" he said. In other words, Microsoft seems to be taking a play from the Apple playbook by creating a relatively locked-down operating system environment, tweaked to make the most of a particular chipset, and optimized for high levels of performance and battery life, despite the potentially small form factors. Apple requires anyone who wants to build an iOS browser to use its underlying WebKit libraries. But Anderson said this move potentially blocked other browser makers from being able to offer a cutting-edge user experience on future versions of Windows. \"Windows on ARM prohibits any browser except for Internet Explorer from running in the privileged \'Windows Classic\' environment. In practice, this means that only Internet Explorer will be able to perform many of the advanced computing functions vital to modern browsers in terms of speed, stability, and security to which users have grown accustomed,\" he said. \"Given that IE can run in Windows on ARM, there is no technical reason to conclude other browsers can\'t do the same.\" Google is backing Mozilla\'s concerns. \"We\'ve always welcomed innovation in the browser space across all platforms and strongly believe that having great competitors makes us all work harder. In the end, consumers and developers benefit the most from robust competition,\" said a Google spokeswoman via email. A Microsoft spokeswoman said the company currently had no comment on the matter. The Enterprise 2.0 Conference brings together industry thought leaders to explore the latest innovations in enterprise social software, analytics, and big data tools and technologies. 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