NOR Gate


A NOR gate is a digital logic gate in electronics that performs the logical NOR operation. This operation outputs a binary value of TRUE or 1 only when both of its input values are FALSE or 0. In other words, it acts as a combination of an OR gate followed by a NOT gate, inverting the output of the OR operation.

Key Takeaways

  1. A NOR gate is a fundamental digital logic gate that performs the logical operation NOR (NOT OR). It outputs high (1) only when both inputs are low (0).
  2. NOR gates can be used to construct other logic gates such as AND, OR, and NOT gates. They can also be combined to create more complex circuits, making them versatile components in digital systems.
  3. Since NOR gates can be made using transistors, they are widely used in integrated circuits to build digital devices like computers, microprocessors, and memory storage systems.


The NOR Gate holds importance in the realm of technology as it is a fundamental building block in the design and creation of digital circuits and systems.

As a universal logic gate, it constructs any necessary digital function by combining multiple instances of it.

NOR Gates perform the operation of OR followed by NOT, yielding an output that is false when any of its inputs are true.

Its versatile nature allows it to be used in a wide variety of applications, such as digital signal processing, memory devices, and computing systems.

By enabling the manipulation of digital signals, the NOR Gate contributes significantly to the functionality of modern electronic devices and the advancement of technology as a whole.


A NOR gate is a digital logic gate that serves a crucial role in electronic communication and computing systems. The purpose of this versatile gate is to produce an output that is true or high only when both of its inputs are false or low.

The name ‘NOR’ is derived from the combination of NOT and OR gate functions, as it performs a negation of the OR operation. This fundamental building block of digital circuits has widespread applications, from designing simple to complex systems, which can include implementing logic functions, constructing memory storage units, and constructing other essential gates in digital systems.

One of the most common uses of NOR gates is the creation of electronic flip-flops or bistable multivibrators, which are employed in memory and data storage devices, such as RAM (random access memory) and registers. These flip-flops can store binary information and serve as basic memory elements in digital systems.

Another significant application of NOR gates is in forming more elaborate digital logic circuits, as they can be used to synthesize any other logic gate or function. This immense flexibility in designing digital electronics systems makes NOR gates a key component in modern digital circuit design and a vital technology term for understanding the intricacies of electronic devices.

Examples of NOR Gate

A NOR gate is a digital logic gate that performs the operation of an OR gate followed by a NOT gate, resulting in an output of “true” or “1” only when both input signals are “false” or “

” Here are three real world examples of NOR gate applications:

Burglar Alarm System: NOR gates can be used in burglar alarm systems to detect if any doors or windows are opened while the system is armed. The alarm system’s control panel receives input signals from sensors installed on each door or window. If all input signals are “false” (meaning all doors and windows are closed), the NOR gate output is “true” and the system remains disarmed. However, if any door or window is opened (input signal is “true”), the NOR gate output becomes “false,” triggering the alarm.

Elevator Control System: Another application of NOR gates can be observed in elevator control systems. In this case, the control system needs to ensure that the elevator doors are completely closed before the elevator can move. The sensors on each door provide input signals to a NOR gate. When both input signals from the door sensors are “false” (indicating that both doors are completely closed), the output from the NOR gate is “true,” allowing the elevator to move. If any door is not closed properly, the NOR gate output becomes “false,” and the elevator is prevented from moving.

Traffic Light Control: In a traffic light control system, NOR gates can be used to ensure that two conflicting traffic signals are never green at the same time. For example, suppose we have two input signals – one for a North-South green light (N-S) and another for an East-West green light (E-W). A NOR gate can be used to control whether the N-S traffic can move based on the status of the E-W light. When the E-W light is red (input signal is “false”), the NOR gate output is “true,” allowing the N-S light to go green. If the E-W light is green (input signal is “true”), the NOR gate output is “false,” and the N-S light remains red.These examples demonstrate the utility of NOR gates in various real-world scenarios, providing safety and control across different systems.


What is a NOR gate?

A NOR gate is a digital logic gate that implements the logical NOR operation. It takes two or more input signals and produces an output signal that is true only when all input signals are false. It can be thought of as an inverter followed by an OR gate.

How does a NOR gate work?

A NOR gate consists of a combination of transistors that act as switches. When all input signals are low (false), all of the transistors are in an off state, allowing the output to be high (true). However, when any of the input signals are high (true), one or more of the transistors turn on, which causes the output to go low (false).

What is the truth table for a NOR gate?

The truth table for a 2-input NOR gate is as follows:

Input A Input B | Output
   0       0    |   1 
   0       1    |   0
   1       0    |   0
   1       1    |   0

What are the applications of NOR gates?

NOR gates are fundamental building blocks in digital circuits and can be used to construct various other logic gates like NOT, AND, and OR gates. They are commonly used in digital systems, computers, arithmetic operations, memory systems, and various control and decision-making applications.

How can I create a NOR gate using other logic gates?

A NOR gate can be created by connecting the output of an OR gate to the input of a NOT gate. This configuration inverts the output of the OR gate, providing the NOR functionality.

Related Technology Terms

  • Boolean Logic
  • Logic Gates
  • Complementary Metal-Oxide-Semiconductor (CMOS)
  • Transistor-Transistor Logic (TTL)
  • Electronic Circuit Design

Sources for More Information

  • All About Circuits: A comprehensive source for electronics and electrical engineering information, including articles and tutorials on NOR Gates.
  • Electronics Tutorials: Offers beginner to advanced electronics tutorials, including detailed information on NOR Gates and their applications.
  • IEEE Xplore: A scholarly research database that offers technical articles on electronics and technology, including studies on NOR Gates and their various applications.
  • Electronics For You: A source for industry news, innovations, and product information, including articles and tutorials on specific electronic components, like NOR Gates.

About The Authors

The DevX Technology Glossary is reviewed by technology experts and writers from our community. Terms and definitions continue to go under updates to stay relevant and up-to-date. These experts help us maintain the almost 10,000+ technology terms on DevX. Our reviewers have a strong technical background in software development, engineering, and startup businesses. They are experts with real-world experience working in the tech industry and academia.

See our full expert review panel.

These experts include:


About Our Editorial Process

At DevX, we’re dedicated to tech entrepreneurship. Our team closely follows industry shifts, new products, AI breakthroughs, technology trends, and funding announcements. Articles undergo thorough editing to ensure accuracy and clarity, reflecting DevX’s style and supporting entrepreneurs in the tech sphere.

See our full editorial policy.

More Technology Terms

Technology Glossary

Table of Contents