AQA 7517 4.6.4.1: Logic gates
The free BugBot lessons that teach this point, a robot to try it on, and the past-paper questions that test it.
What it covers
At GCSE you met AND, OR and NOT, drew their truth tables, and built a half adder from XOR and AND (lessons F9.1 and F9.2). A level adds two more gates, NAND and NOR, asks you to write expressions in your board's notation, and then treats those expressions as algebra you can rearrange and simplify. This lesson sets out the six gates and the symbols, so the rest of the module has a shared language.
- The six gates
- Three ways to write the same thing
- Gates in Python
- NAND can build anything
- A robot example
Or do it in the simulator, with tasks that mark themselves
Lessons that teach it
- A8.1 Logic gates and notation Boolean algebra and logic circuits
NOT, AND, OR, XOR, NAND and NOR, the notation each board uses, and why NAND alone can build anything. - A8.2 Circuits, expressions and truth tables Boolean algebra and logic circuits
Reading and drawing circuits, defining a problem in Boolean logic, and sum of products from a truth table. - A8.7 Half adders and full adders Boolean algebra and logic circuits
The full adder's expressions, building it from half adders, and chaining full adders into a ripple carry adder. - A8.8 D-type flip-flops and clocks Boolean algebra and logic circuits
Clock signals, edge triggering, the D-type flip-flop as one bit of memory, registers and a divide-by-two counter. - A8.9 Project: the robot's safety logic Boolean algebra and logic circuits
From a rule table to a Karnaugh map, a simplified expression, a proof and a robot that stops for the right reasons.
Try it on a robot
The task from A8.1 Logic gates and notation, running here. Change the program and press Run.
The specification is AQA's own document; this page says which of our lessons teach point 4.6.4.1 and is not endorsed by the board.