NOR Gate

A NOR gate is a fundamental digital logic gate that performs the logical NOR (NOT-OR) operation on two or more binary inputs to produce a single binary output. The output of a NOR gate is the complement of the result obtained from an OR gate. In other words, the output of a NOR gate is high (1) only when all of its input signals are low (0); otherwise, the output is low (0).

The logic symbol for a NOR gate is represented as follows:

   ----       ----
A |    |    B |    |
  | NOR |      |    |
---|    |    ---|    |
   ----       ----
     Output

In this symbol:

  • A and B represent the input signals.
  • The NOR symbol in the middle represents the logical NOR operation.
  • The output is the complement of the OR operation’s output.

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

ABOutput
001
010
100
110

The truth table shows the output for all possible combinations of input values. As per the truth table, the output is 1 only when both inputs are 0; otherwise, the output is 0.

NOR gates have various applications in digital systems, including:

  • Building more complex logic gates, such as AND, NOT, and XOR gates.
  • Logic circuits for control and decision-making.
  • Implementing universal gates that can realize any logical function.
  • Memory circuits, such as static random-access memory (SRAM) cells.
  • Creating latch and flip-flop circuits for sequential logic.

By combining NOR gates with other logic gates, intricate digital circuits can be designed to perform a wide range of tasks in electronic devices and systems.