Hardware Description Language
Last Updated :
17 Apr, 2023
Introduction:
Most people are familiar with traditional programming languages like C, C++, Java, Python etc, which are used to develop software applications. However, many are unaware of Hardware Description languages like Verilog and VHDL. In this article, we will discuss about hardware description language. Let's go.
History:
The concept of a hardware description language as a medium for design capture was first introduced in the1950s, but wide adoption by the design community did not start until after 1985. Historically, the development of software programming languages stimulated the evolution of HDLs.
The first hardware description language came in late 1960, which looks like a traditional language. The first HDL was called "Description Language for Hardware" (DLH) and was developed by IBM in the late 1960s. However, it was not widely used because of its complexity and difficulty to use. In the subsequent years, various other HDLs came into existence such as ABEL and PALASM which gained popularity in the 1980s.
In the mid-1980s VHDL was introduced by the US Department of Defence.VHDL was designed to describe digital circuits, which aimed to develop high-performance digital circuits for military applications. In the same year, Verilog was introduced by Phil Moorby and Prabhu Goel owned by Gateway Design Automation. It was originally intended to be used for verification, but it became popular as HDL.
What is HDL?
In the history of Digital computers, various notations have been developed for capturing the logical behaviour of digital circuits at different levels of abstraction. Examples of such notations include boolean equations, timing charts, state transition tables, schematics, and hardware description languages.
Hardware Description Language (HDL) is a programming language that is used to describe the structure, behaviour and timing of electronic circuits, and most commonly, digital logic circuits. HDLs are used for designing processors, motherboards, CPUs and various other Digital circuits. In addition to their use in circuit design, HDLs serve the purpose of simulating the circuit and verifying its response. Many HDLs are available, but the most popular HDLs so far are Verilog and VHDL.
- HDLs resemble a traditional programming language, but they are not identical. These are specifically designed to describe the hardware.
- Unlike traditional programming languages that primarily represent serial operations, HDL distinguishes itself by representing extensive parallel operations.
Purpose of HDLs:
HDLs allow for behavioural, register transfer, gate, and switch level logic, allowing designers to define levels in detail. Behavioural level logic allows for a set of instructions executed sequentially, and register transfer level logic allows for the transfer of data between registers, driven by an explicit clock and gate level logic, which defines the individual gate level logic. Similar to the relationship of HTML and CSS to web development, Verilog/VHDL has a similar relationship to FPGAs and other configurable logic devices. HDLs can be used to design and describe the layout of digital systems from simple flip-flop memory units to complex communications protocols.
Circuit Design: It provides a way to design digital circuits that meet the required specifications.
Simulation: It helps the designer to test and verify the digital circuit before it is built.
Verification: It provides designers to verify the functionality of the Digital circuit by testing it against different inputs and ensuring that the circuit functionality is correct and meets the desired functionality.
Synthesis: HDLs can be used to synthesize digital circuits. Synthesis is a process of automatically generating circuits from HDL code.
Timing Analysis: It provides designers to analyse the timing behaviour of digital circuits and ensure that the circuits meet the timing requirements.
Design Reusability: HDLs provide a way to design reusable components that can be used for multiple circuits design and reduce time and effort, which improves overall design quality.
Optimization: It Provides a way to optimise the design of digital circuits for performance.
Popular HDLs:
There are several HDLs available but the most popular HDLs are Verilog and VHDL.
Verilog: Verilog stands for verification logic. It is used to model and stimulate the Digital circuits Application-Specific Integrated Circuits (ASICs) and Field-Programmable Gate Arrays (FPGAs).
Syntax:
module module_name(inputs,output)
//statements
end module
VHDL: VHDL stands for Very High-speed Integrated Circuit Hardware Description Language (VHSIC). It is used to design digital circuits. It is often used to design complex Digital circuits such as Microprocessors and Digital Signal Processors.
Syntax:
library ieee;
use ieee.std_logic_1164.all;
entity Circuit_name is
Port ( a : in STD_LOGIC;
b : in STD_LOGIC;
out1 : out STD_LOGIC);
end Circuit_1;
-----------------------------------------------------
architecture Behavioral of Circuit_name is
begin
// statements
end Behavioral;
Similar Reads
Difference Between Hardware Description Language and Software Language
Hardware and software are fundamental components of modern computing systems. While software languages are widely known for programming applications, hardware description languages (HDLs) play a crucial role in designing and describing electronic circuits. Ever wondered how Hardware Systems are desi
5 min read
Language Processing Activities
Language processing activity bridges the ideas of software designers with actual execution on the computer system. The designer expresses the idea related to the application domain of the software. To implement these ideas, the description of the ideas has to be interpreted as related to the executi
3 min read
What is Fourth Generation Programming Language?
The language which is used to create programs is called a programming language. It comprises a set of instructions that are used to produce various kinds of output. A Fourth Generation Programming Language (4GL) is designed to make coding easier and faster for people by using more human-friendly com
4 min read
I/O Hardware in Operating System
I/O Hardware is a set of specialized hardware devices that help the operating system access disk drives, printers, and other peripherals. These devices are located inside the motherboard and connected to the processor using a bus. They often have specialized controllers that allow them to quickly re
6 min read
What is Assembly Language?
When we talk about programming languages the first thing that comes to our mind is languages like C, C++, Java, Python, etc. But those languages hide the actual working i.e., that abstracts many things from users. But there is a language that really lies on basic concepts behind the programming or i
9 min read
What is High Level Language?
Computer languages have a huge importance in the digital world. If you want to create anything such as an application, website, software, or game you need to write it using a coding language, which is most probably a high-level language because they are easier to use and understand by humans. In thi
7 min read
What is Machine Language?
Machine language is a low-level programming language that is understood by computers. Machine language is made up of binary bits 0 and 1. Machine language is also known as machine codes or object code. As machine language consists of only 0 and 1, that's why it is difficult to understand in raw form
4 min read
HDL Model of Combinational Circuits
Any language from a class of computer languages and/or programming languages used for the formal description of digital logic and electronic circuits is known as a hardware description language, or HDL, in the field of electronics. To create executable hardware specifications, HDLs are employed. The
4 min read
What is a Character (CHAR)?
In progrаmmiÕ¸g, dаtа is stored аոd mаnupulаted ÑÕ¸ vаrious forms, kÕ¸owÕ¸ аs dаtа types. OÕ¸e fuÕ¸dаmeÕ¸tаl dаtа type is the chаrаcter, ofteÕ¸ly аbbreviаted аs chаr. UÕ¸derstаոdiÕ¸g chаrаcters аոd their use ÑÕ¸ progrаmmiÕ¸g is crucÑаl for hаոdliÕ¸g text, symbols, аոd more complex dаtа structures effectively. Wh
3 min read
Telephone Keypad Scanner
A telephone keypad is designed using a PLD(Programmable Logic Device). The keypad is wired in a matrix form with a switch at the intersection of each row and column. The purpose of this keypad scanner is to determine which has been pressed and output a binary number N=N3 N2 N1 N0 which corresponds t
2 min read