The Central Processing Unit (CPU), often called the "processor," is the computing part of the computer. It handles arithmetic and logical calculations, and decodes and executes instructions from hardware and software. It is considered to be the heart and brains of the computer, as every single operation is processed by the CPU.

The CPU consists of the ALU (Arithmetic Logic Unit), the CU (Control Unit), and the Memory Unit, as well as input and output devices. The Arithmetic Logic Unit is what handles the mathematical and logical calculations. Any complex mathematical equations are done with repetitions of the most simple mathematical equations, such as adding, subtracting, multiplying and dividing. The Memory Unit stores instructions, data, intermediate results, and final results before they’re handed off to the output device. Data and instructions are simply that; instructions that the CPU uses. Intermediate results are stored while the ALU is processing calculations, and the final results are stored there as well until they are given to the output device. The Control Unit is what oversees all operations.


The CPU has four main functions while processing instructions. It fetches, decodes, executes, and writes back.

Fetch: This means that the CPU fetches instructions from the program being run. Every instruction has an address, and the CPU has a program counter that keeps track of which instruction is being executed and which to execute next.

Decode: The instruction from the program must be translated from Assembly code into binary code so that the CPU can understand it.  

Execute: The CPU can use its ALU to calculate functions, move around data between memory storage, and also move to different addresses in the program.

Writeback: Finally, the CPU feeds the results of calculations or operations to the output device, which then uses the information to do whatever it needs said data for.

The first CPU was created by Intel in 1971, called the Intel 4004.


This consisted of 2,300 transistors, and was able to perform 60,000 operations per second. A transistor is simply a switch that connects or disconnects a wire (or just the flow of electricity) like in a light switch. These days, the Intel i7 6950x can perform 317,900 MIPS (Millions of Instructions Per Second) at 3.0 Ghz.


For more history about CPU’s, click here.

For more about the Intel i7 6950x, click here.

For sources used in this article, click here.

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