Intel Reverse-Engineered AMD64

After investigating the instruction sets used by 64-bit chips from AMD and Intel, an industry analyst has concluded that Intel reverse-engineered the AMD64 instruction set to create its own 64-bit microprocessor architecture.

Tom Halfhill, an analyst at In-Stat/MDR in San Jose, said Monday that he had compared the instruction sets of AMD’s 64-bit chips, called AMD64, with the 64-bit extensions to be used in the Intel Xeon processor and future desktop chips. The smoking gun, Halfhill said, was Intel’s choice to mimic a decision AMD made in its early Opteron designs, and later reversed.

Speculation that Intel had reverse-engineered AMD’s processor began circulating almost immediately after Intel announced its own 64-bit plans in February. AMD announced plans to develop its 64-bit Opteron processor, then code-named “Hammer”, in Oct. 2001, and began shipping it in April 2003. Intel’s “Nocona”, the first chip to use its own 64-bit extensions, will launch this quarter with the Intel Extended Memory 64 Technology, or “Intel EM64T”.

While exactly copying a processor’s microarchitecture would be illegal, creating a compatible product through the use of an original “clean room” design is legally protected. According to Halfhill, Intel clearly reverse-engineered AMD’s products, a tactic AMD and other X86 chip designers have used to quickly catch up to Intel’s historical leadership in the design of new microprocessors.

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