The binary translation happens on install of apps, and unused APIs consume no CPU time. As for storage, if a unified platform supported every legacy API, the s

The binary translation happens on install of apps, and unused APIs consume no CPU time. As for storage, if a unified platform supported every legacy API, the same problem exists whether it is x86 or ARM, so that seems orthogonal to this discussion. Regardless it's worth considering how mobile and tablet devices have exploded in capabilities (my smartphone has 2GB of RAM. Windows XP required 64MB). Would it support every legacy API? Not necessarily. Being unified doesn't necessarily mean that, and Microsoft has threatened Win32 and friends for time eternal (e.g. http://www.windowsdevcenter.com/pub/a/windows/2004/07/13/winfx.html http://www.windowsdevcenter.com/pub/a/windows/2004/07/13/win...). Unified can simply mean that from this point forward, WinXX is unified, or the .NET platform is holistic and all-encompassing (which has always been the goal of that platform, but somehow keeps getting screwed up), or whatever.