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How can AMD K8 and AMD64 describe the same processor? Are AMD K8 and AMD64 the same thing?

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up vote 7 down vote accepted

AMD K8 is a processor microarchitecture, which was the first to implement the AMD64 instruction set as an extension to the x86 architecture.

The following x86 processors use the AMD K8 microarchitecture:

  • Athlon 64 X2
  • Athlon 64 FX
  • Athlon 64
  • Sempron
  • Opteron (Later also released using K10)
  • Turion 64

Think of it as being analogous to the Intel versions; the Nehalem and Sandy Bridge microarchitectures have the Intel 64 instruction set extension and are implemented in the processors like Core 2 Duo and Core i7.

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When a new microarchitecture is made, does it need a new instruction set? Are there any microarchitectures that use the same instruction set as previous ones? – tony_sid Apr 23 '11 at 1:44
No, not necessarily. That said, most do add at least some extensions to the previous processor's instruction set. For example, the Sandy Bridge microarchitecture contains AVX and VEX extensions to the x86 set for improved floating point and programmable opcodes, respectively. I can't really think of any ones that don't at least have some small extensions. – Hyppy Apr 23 '11 at 3:48

"AMD K8" is the processor. "AMD64" is the instruction set.

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