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AMD 64bit, WindowsXP

  1. Nov 8, 2004 #1
    Hey does anyone know if WindowsXP will run on the new AMD 64bit processors? After all, are AMD processors compatible with pentium (i.e. x86 processors)?
  2. jcsd
  3. Nov 8, 2004 #2
    Last edited: Nov 8, 2004
  4. Nov 8, 2004 #3
    Backwards compatibility of AMD 64-bit CPUs

    AMD's 64-bit processors are backwards compatible:

    • AMD64 represents a break with AMD's past behavior of following Intel's standards, but follows Intel's earlier behavior of extending the x86 architecture, from the 16-bit 8086 to the 32-bit 80386 and beyond, without ever removing backwards compatibility. The AMD64 architecture extends the 32-bit x86 architecture (IA-32) by adding 64-bit registers, with full 32-bit and 16-bit compatibility modes for earlier software.

    This is why AMD managed to outmaneuver Intel in the 64-bit arena. Intel's 64 bit offering, the Itanium, is not backwards compatible with 32-bit operating systems.
  5. Nov 9, 2004 #4
    This is very interesting indeed! I didn't know that AMD64bit processors are backward compatible.
  6. Nov 9, 2004 #5


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    Yes, the Itanium is backwards compatible with 32-bit operating systems. The implementation is messy, but it does exist.

    I should rephrase and state that an x86 compatibility layer does exist. This compatibility layer does include support for 32-bit operating systems. The Itanium does have support for most of the instruction sets present on an x86, with the exclusion of SSE2. I'm not sure about the Itanium2.

    I also wouldn't say that AMD "outmanuveured" Intel. Each processor has it's distinct advantages and disadvantages.
    Last edited: Nov 9, 2004
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