Logic Gates

KS3 Computer Science

11-14 Years Old

48 modules covering EVERY Computer Science topic needed for KS3 level.

GCSE Computer Science

14-16 Years Old

45 modules covering EVERY Computer Science topic needed for GCSE level.

A-Level Computer Science

16-18 Years Old

66 modules covering EVERY Computer Science topic needed for A-Level.

GCSE Logic Gates and Logic Circuits (14-16 years)

  • An editable PowerPoint lesson presentation
  • Editable revision handouts
  • A glossary which covers the key terminologies of the module
  • Topic mindmaps for visualising the key concepts
  • Printable flashcards to help students engage active recall and confidence-based repetition
  • A quiz with accompanying answer key to test knowledge and understanding of the module

A-Level Logic gates and circuits (16-18 years)

  • An editable PowerPoint lesson presentation
  • Editable revision handouts
  • A glossary which covers the key terminologies of the module
  • Topic mindmaps for visualising the key concepts
  • Printable flashcards to help students engage active recall and confidence-based repetition
  • A quiz with accompanying answer key to test knowledge and understanding of the module

Logic gates execute basic logical functions and are the core components of digital integrated circuits.  Most logic gates accept an input of two binary values and provide an output of a single binary value.  Some circuits have a few logic gates, while others have many logic gates.  A microprocessor has millions of logic gates.
The connection between the input and the output is based on a definite rationale.  These gates are enforced using electronic switches like diodes and transistors.  As a custom, primary logic gates are produced using Complementary Metal Oxide Semiconductor (CMOS) technology, Field Effect Transistor (FET) and Metal Oxide Semiconductor Field Effect Transistor (MOSFET).

Types of Logic Gates

Here are the 7 different types of logic gates:

NameExplanationNotation
ANDTrue if A and B are both TrueZ = A AND B
ORTrue if either A or B is TrueZ = A OR B
NOTInverts value: True if input is False; False if input is TrueZ = NOT A
XORTrue if either A or B is True, but False if both are TrueZ = A XOR B
NANDAND followed by NOT: False only if A and B are both TrueZ = A NAND B
NOROR followed by NOT: True only if A and B are both FalseZ = A NOR B
XNORXOR followed by NOT: True if A and B are both True or both FalseZ = A XNOR B

Highly complex operations are made possible by combining thousands or even millions of logic gates.  The highest number of logic gates on an integrated circuit is established by the size of the chip divided by the size of the logic gates.  Smaller transistors mean more complicated and quicker processors.

Logic Gate Truth Tables

Every possible input and output scenario are covered in a truth table.

AND

Input AInput BOutput Z
000
010
100
111

OR

Input AInput BOutput Z
000
011
101
111

 NOT

Input AOutput Z
10
01

XOR

Input AInput BOutput Z
000
011
101
110

NAND

Input AInput BOutput Z
001
011
101
110

NOR

Input AInput BOutput Z
001
010
100
110

XNOR

Input AInput BOutput Z
001
010
100
111

Application of Logic Gates

Wherever the existence of any one or more than one incident is needed to be observed or some behaviour are to be taken after their existence, in all those instances OR gates can be used.  For example, in an industrial plant, if one or more than one specification goes beyond the safe value, some security measures must be done.
AND gates are used as Enable gate and Inhibit gate.  Enable gate means acceptance of data through a pathway while Inhibit gate is the opposite of that process which means rejection of data through a pathway.
XOR and XNOR gates are used in identity generation and identity check operation.
NOT gates are also called inverter because they switch the output given to them and show the reverse outcome.

Advantages of Logic Gates

  • Logic gates are quick yet use low energy.
  • Logic gates don’t get overworked.
  • Logic gates can lessen the prescribed number of I/O ports needed by a microcontroller.
  • Logic gates can bring about straightforward data encryption and decryption.