"As Intel licenses AMD the right to use the original x86 architecture (upon which AMD's x86-64 is based), these rival companies now rely on each other for 64-bit processor development. This has led to a case of mutually assured destruction should either company revoke its respective license. Should such a scenario take place, AMD would no longer be authorized to produce any x86 processors, and Intel would no longer be authorized to produce x86-64 processors, forcing them back to the now-obsolete 32-bit x86 architecture." Wikipedia