Central processing unit (CPU), as the computing and control core of computer system, is the final execution unit of information processing and program running. Since its emergence, CPU has made great progress in logic structure, operating efficiency and functional extension. CPU appeared in the era of large-scale integrated circuits, and the iterative update of processor architecture design and the continuous improvement of integrated circuit technology prompted its continuous development and improvement. CPU has been developing rapidly since its birth, from being used exclusively in mathematical calculation to being widely used in general-purpose calculation, from 4-bit to 8-bit, 16-bit, 32-bit processors, and finally to 64-bit processors, from the incompatibility of various manufacturers to the emergence of different instruction set architecture specifications.