This key facts covers Order of Operations in Logic Circuits within Truth Tables for GCSE Computer Science. Revise Truth Tables in 3.4 Computer Systems for GCSE Computer Science with 15 exam-style questions and 15 flashcards. This topic appears less often, but it can still be a useful differentiator on mixed-topic papers. It is section 9 of 11 in this topic. Use this key facts to connect the idea to the wider topic before moving on to questions and flashcards.
Order of Operations in Logic Circuits
Just like mathematics has BIDMAS/PEMDAS, Boolean logic has an order of operations:
| Priority | Operation | Example |
|---|---|---|
| 1st (highest) | Brackets / Parentheses | Evaluate (A OR B) before anything else |
| 2nd | NOT | NOT(A) is evaluated before AND/OR |
| 3rd | AND | A AND B is evaluated before OR |
| 4th (lowest) | OR | OR is evaluated last |
Example: NOT(A) AND B OR C
- Step 1: Calculate NOT(A)
- Step 2: Calculate NOT(A) AND B
- Step 3: Calculate [NOT(A) AND B] OR C
Practice questions for Truth Tables
How many rows are needed in a truth table with 2 inputs (not including the header row)?
Explain why truth tables are useful when designing or testing logic circuits.