AMD64 is, as far as I know, not a standard. Even if it was, being a standard does not mean that it is free, easy and legal for others to implement. Some standa

AMD64 is, as far as I know, not a standard. Even if it was, being a standard does not mean that it is free, easy and legal for others to implement. Some standard bodies require a patent sharing agreement or licenses being provided for a "reasonable" cost, but what is reasonable is often a topic of discussion. x86_64 also incorporates a 32-bit compatibility, which is copyright protected by Intel and only a handful of licensees exist, with no new licenses having been signed in the past decade or so. I don't think you can implement AMD64 without also acquiring an x86 license from Intel.