# 4 bit Arithmetic and Logic Unit (ALU ) – Design concept Schematic Circuit Diagram

Hey there, In this section, I have made a nice conceptual circuit diagram that will help you to understand how ALU inside the computer works.

**Schematic Diagram:**

## What is ALU?

ALU is a combination of a digital circuit that does **the arithmetic operation** (like Adding two number, subtracting, multiply, division and logic** operation** (like AND, OR, NOR, NOT, XOR etc )

In this project I have made this device just for addition , subtracting and ANDing to show you basic concept behind the ALU unit .

## The circuit explanation

In the previous section of making calculator project, i have explained the basic concept of Adder you can visit there by this link. So, i am assuming you have read that project, In this project, i have used IC packages directly to add the number, and an XOR gate is used to make it subtractor and a **AND** gates IC for **AND**ing

The selection process is manual in this project, but you can use a decoder IC to select automatic after pressing a button to try it your self. (look ground of 74hc244 IC is individually selected in all three operations). You can simply give binary input from input pins push buttons and corresponding binary output is observed in 74hc244 and then BCD to seven segment decoder 4511 IC is used to represent an equivalent decimal number. That’s all the concept behind the ALU unit inside the computer. If you have any confusion please feel free to tell me. I am always with you. you can either comment below or message me directly.