Windows 8 is the most dramatic transition in the history of Microsoft's Windows since the introduction of Windows 3, when the company told users to move from command-line input to a mouse-controlled, Windows-based input. Similarly, Windows 8 has a strong focus on a tile-based interface derived from touchscreen smartphones and tablets. Just like Windows 3 moved toward the mouse, Windows 8 moves toward the use of touch. Microsoft is facing substantial criticism especially from UI experts that claim that the touch interface is too restrictive and not transparent enough for mainstream users. With the introduction of the new OS, Microsoft is also offering, for the first time, a Windows version for ARM-based tablets and entry-level computers with a platform that lacks x86 application compatibility. The introduction of Windows RT is the most significant platform expansion in Windows history and pays tribute to the fact that more than 2 billion ARM processors are now shipped every quarter.