Visual Studio 2013

* Version - 12.0

* .Net Framework Version - 4.5.1

* Overrides 4.0, so all dll's under 4.0 folder is replaces.(%WINDIR%\Microsoft.NET\Framework)

* 4.5.1 Reference assemblies are in

C:\Program Files (x86)\Reference Assemblies\Microsoft\Framework\.NETFramework

* 4.5.1 GAC is usual location - C:\windows\microsoft.net\assembly(up until 3.5 in in c:\windows\assembly)
  here are 3 types of GAC’s now available
    · GAC_32
    · GAC_64
    · GAC_MSIL
  While the 32-bit platforms have GAC_32 and GAC_MSIL, the 64-bit have all the three. GAC_32 contains assemblies that are specific to the 32-bit platform and GAC_64 specific to the 64-bit platform. The GAC_MSIL contains the assemblies that are platform agnostic. While trying to load assemblies from the GAC, the CLR first looks at the GAC specific to the platform. If it is unable to find the same, it then moves to the GAC_MSIL.