VHDL code for AND and OR Logic Gates (original) (raw)

Last Updated : 12 Jul, 2025

Prerequisite - Introduction of Logic Gates

Design and implement the AND and OR logic gates using VHDL (VHSIC Hardware Description Language) programming language.

Different Types of VHDL Modelling Styles

The architecture of VHDL code is written in three different coding styles :

1. Dataflow Modelling
2. Behavioral Modelling
3. Structural Modelling

1. Logic Development for AND Gate: The AND logic gate can be realized as follows -

The truth table for AND Gate is:

Implementation of Dataflow Modelling - Below is the implementation of the above logic in the VHDL language (Dataflow Modelling).

-- VHDL Code for AND gate

-- Header file declaration

library IEEE; use IEEE.std_logic_1164.all;

-- Entity declaration

entity andGate is

**port**(A : in std_logic;      -- _AND gate input_
     B : in std_logic;      -- _AND gate input_
     Y : out std_logic);    -- _AND gate output_

end andGate;

-- Dataflow Modelling Style -- Architecture definition

architecture andLogic of andGate is

begin

Y <= A AND B;

end andLogic;

2. Logic Development for OR Gate: The OR logic gate can be realized as follows -

The truth table for OR Gate is:

Implementation of Dataflow Modelling - Below is the implementation of the above logic in the VHDL language (Dataflow Modelling).

-- VHDL Code for OR gate

-- Header file declaration

library IEEE; use IEEE.std_logic_1164.all;

-- Entity declaration

entity orGate is

**port**(A : in std_logic;      -- _OR gate input_
     B : in std_logic;      -- _OR gate input_
     Y : out std_logic);    -- _OR gate output_

end orGate;

-- Dataflow Modelling Style -- Architecture definition

architecture orLogic of orGate is

begin

Y <= A OR B;

end orLogic;