multithreading - What has changed in the memory model in .NET 4.5? -

multithreading - What has changed in the memory model in .NET 4.5? -

i read puzzling line in peter richtie blog , need help understand meaning prior .net 4.5 programmed .net memory model : http://msmvps.com/blogs/peterritchie/archive/2012/09/09/thread-synchronization-of-atomic-invariants-in-net-4-5.aspx

has 'usual' .net memory model (such 1 discussed in jeffrey richter book clr via c# edition 1 , 2 (i haven't read 3d)) changed in .net 4.5?

is there article conscious explanation?

multithreading .net-4.5 shared-memory