How come x86 works on 64-bit Windows 7, Windows 8, and even the server configuration machines that are in 64 bit OS?
Because of WoW64 (Windows on Windows 64-bit). Basically, it is a 32 bit emulator, which allows you to run 32 bit programs in a 64 bit operating system.
X86 vs X64 vs Any CPU: What are the clear differences?
X86 is the mode for 32 bit applications, named after the 80×86 series CPUs. A 32 bit application can address 4 GB of memory.
X64 is the mode for 64 bit applications. It’s a shortening of the name x86-64 which is the 64 bit mode of the x86 instruction set. A 64 bit application can address 18 PB (petabyte) of memory, which translates to all available memory (for the forseeable future).
The Any CPU mode allows for compilation to each of the other two modes.
The compilation mode is just an instruction for the JIT compiler for how it is allowed to compile the CIL code into machine code. The CIL code itself is the same for all modes.
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solved X86 vs X64 vs Any CPU [closed]