CPU, internal memory and input / output devices are three major core components of electronic computers. Its function is mainly to explain the computer instruction and the data in the computer software. The CPU is composed of a bus, control, and register, and a bus that implements them between them. Almost all of the CPU operation principle can be divided into four phases: fetch, decodes, executes, and writeback. The CPU takes out the instruction from the memory or cache memory, puts the instruction register, and decodes the instruction, and executes the instruction. The so-called computer programmability is mainly to programming the CPU.
