An Intel 64 architecture processor supports existing IA 32 software because it is able to run all non 64 bit legacy modes supported by IA 32 architecture Most existing IA 32 applications also run in compatibility mode on page Vol 1 2 21 of Intel 64 and IA 32 Architectures Software Developer s Manual September 2014 which might or might not imply that Intel 64 architecture and IA 32 architecture are two things the only link is the Intel64 processor