Truth tables, logic gates and Boolean algebra.
Understand digital circuits with illustrated explanations, worked examples, past-paper discussions and revision questions.
Study sections
Follow the order or choose a sectionDescribing a Circuit — Functional Specification and Truth Tables
You’re playing tic-tac-toe. Can we build a small electronic box that looks at the board and lights a red LED if X has won? Before build…
02Logic Gates — NOT, AND, OR and Friends
A lift door should open only if the lift has stopped AND someone pressed the button . A fan should run if the switch is on OR the timer…
03Boolean Algebra — The Rules
In school maths, you learned rules like a × 1 = a and a + 0 = a. They let you simplify long expressions. Boolean algebra has its own ru…
04De Morgan's Laws
“It’s not true that (I’m hungry or I’m tired)” means “I’m not hungry and I’m not tired.” When you push a NOT inside the brackets, OR tu…
05Sum of Products (SOP) and Minterms
You have a truth table, and you want a formula. Here’s the trick: look only at the rows where the output is 1 . Write a small “detector…
06How to Solve Week 2 Exam Questions
Every Week 2 question from the 11 past papers is on this page, with the exact paper it came from. For each type you first learn the met…