What is a CPU?

(Central Processing Unit)

CPU or Central Processing Unit is the heart and brains of every computer.

Every single operation that you do with your computer is processed in CPU. The performance of your computer is based on simple mathematical operations. CPU is the device, that controls all the operation.. Let's say we are using a calculator to add two numbers. The numbers are entered from your keyboard. The keyboard controller turns all the information you have entered into the binary code. Binary code consist of sequences of 0 and 1.

• Main functions of CPU
• Fetch

All the instructions are stored in memory. Each instruction has is address. The processor takes this address number from the program counter. Program counter is responsible for tracking what instructions CPU should execute next. So fetching basically means taking the instruction from the memory.

• Decode

  CPU understands instructions, that are written in Assembly programming language. All the programs, that must be executed, are translated to Assembly instructions. Different CPUs understand different instructions, so Assembly code must be decoded into binary instructions which are understandable to your CPU. This step is called decoding

• Execute

During the procedure of instruction execution, tree things can be done. Firstly, CPU can do some calculations. To execute calculations ALU is used. Secondly, CPU can move data from one memory location to another. And thirdly, CPU can jump to different address if it is needed. So basically, one of those three options is executed during this step.

Save:

CPU must give some feedback after executing the instruction. The output data is written to the memory. In this phase program counter is incremented. 

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Main components of  CPU

1. ALU (Arithematic and logic unit)
2. CU   (Control Unit)

ALU:

Stands for "Arithmetic Logic Unit." An ALU is an integrated circuit within a CPU or GPU that performs arithmetic and logic operations. Arithmetic instructions include addition, subtraction, and shifting operations, while logic instructions include boolean comparisons, such as AND, OR, XOR, and NOT operations.

CU:

The control unit is basically circuitry inside the CPU, controlling the operations inside the CPU and "directing traffic" in a sense. The functions a control unit performs can depend on the type of CPU, since the varying degrees of architecture between all the different CPUs will determine the functions of the control unit.