Working Mechanism of a CPU chip in x86 architecture Part 1 : Components of the CPU

Feb-17-2025, Monday

Author: Deepsu Gautam

A CPU (Central Processing Unit) is the brain of a computer. It takes instructions, process them and executes them. The x86 architecture is one of the most common CPU architectures that is used in most Windows and Linux based PCs.

Components of the CPU:

Control Unit (CU) :

1. Directs how data moves within CPU.
   
   

2. Tells different parts of computer what to do.

3. Fetches instructions from main memory, decodes them and executes them.
   
   
   Hence, CU is a part of CPU that controls overall processes occuring in the CPU.
   
   

Airthmetic Logic Unit (ALU) :

1. Performs mathematical calculations (addition, subtraction, multiplication, divison) and logical operations (AND, OR, NOT).
   
   

2. This is where the actual thinking happens.

Hence ALU is a part of CPU that does the calculations and operations.

Registers : (Detail Explaination in next part)

1. Small fast memory location inside CPU.

2. Stores data temperorarily for quick access.
   
   

Cache Memory :

1. Very fast memory located inside the CPU.
   
   

2. Stores frequently used instruction and data to speed up execution.
   
   

3. Usually divided into 3 groups : L1 (smallest, fastest and closest to the cpu), L2(Larger and slower than L1) and L3(Largest and shared among CPU cores).
   
   

Bus Interface Unit :

1. Manages communication between the CPU and other components (Main memory, etc).
   
   

2. Uses buses (data pathways) to send and recieve information.
   
   

(Note : The next blog part 2 will contain a detailed information of registers and how they work in x86 architecture)