Logic Circuits (Cambridge (CIE) IGCSE Computer Science)

Revision Note

James Woodhouse

Written by: James Woodhouse

Reviewed by: Lucy Kirkham

Logic Circuits

What is a logic circuit?

  • A logic circuit performs logical operations on binary information

  • Logic gates are core components of logic circuits

  • Based on the arrangement of logic gates and the input signals, the circuit performs a specific function

  • A logic diagram is a visual representation of a combinations of logic gates within a logic circuit

  • Brackets are used to clarify the order of operations

  • An example logic diagram for the Boolean expression Q = NOT(A OR B) would be:

logic circuit1
  • In the logic diagram above, the inputs are represented by A and B

  • P is the output of the OR gate on the left and becomes the input of the NOT gate

  • Q is the final output of the logic circuit

Examiner Tips and Tricks

You may be asked to draw a logic circuit from a logic statement or a Boolean expression OR write the logical expression that is expressed in the logic diagram using Boolean expression operators

Logic circuits will be limited to a maximum of three inputs and one output

Example of combining logic gates

10-boolean-logic
  • P = (A OR B) AND NOT C 

Worked Example

A sprinkler system switches on if it is not daytime (input A) and the temperature is greater than 40 (input B)

Draw a logic circuit to represent the problem statement above

[2]

screenshot-2023-05-30-at-08-34-38

Last updated:

You've read 0 of your 10 free revision notes

Unlock more, it's free!

Join the 100,000+ Students that ❤️ Save My Exams

the (exam) results speak for themselves:

Did this page help you?

James Woodhouse

Author: James Woodhouse

Expertise: Computer Science

James graduated from the University of Sunderland with a degree in ICT and Computing education. He has over 14 years of experience both teaching and leading in Computer Science, specialising in teaching GCSE and A-level. James has held various leadership roles, including Head of Computer Science and coordinator positions for Key Stage 3 and Key Stage 4. James has a keen interest in networking security and technologies aimed at preventing security breaches.

Lucy Kirkham

Author: Lucy Kirkham

Expertise: Head of STEM

Lucy has been a passionate Maths teacher for over 12 years, teaching maths across the UK and abroad helping to engage, interest and develop confidence in the subject at all levels.Working as a Head of Department and then Director of Maths, Lucy has advised schools and academy trusts in both Scotland and the East Midlands, where her role was to support and coach teachers to improve Maths teaching for all.