Strange registry value for PROCESSOR_ARCHITECTURE for Intel and AMD processor

Question

I was having a small task to find whether the system is 32-bit or 64-bit machine during installation?
I figured the way by getting the value of registry PROCESSOR_ARCHITECTURE located in HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Session Manager\Environment\ folder but I was surprised to find that value was AMD64 but my processor was Intel64 Family 6 Model 23 Stepping 10, GenuineIntel?
So why AMD64 for Intel64 bit processor?

Answer 1

According to documentation The 64 bit extensions to the x86 architecture were invented and first implemented by AMD.

That's why you get AMD64 and also the registry key is PROCESSOR_ARCHITECTURE which tells the underlying architecture used by processor which is off course AMD64.

For information,
Intel laggards to the 64 bit architecture because they were hoping to transition away from x86 architecture and move towards IA64. IA64 already existed in the form of the Itanium and Intel was hoping to transition towards that. Despite being a far better and more efficient architecture, lacking the inherent design flaws of x86, it suffered through lack of compatibility and it never took off as excepted in the commercial space. AMD on other hand, effectively forced Intel's by introducing the Sledgehammer, which was effectively a 64bit chip based on the x86 architecture. Hence the name AMD64.