AQA 7517 4.5.5.2: ASCII and Unicode
The free BugBot lesson that teach this point, a robot to try it on, and the past-paper questions that test it.
What it covers
A byte is often not one number but several small fields packed together: a status byte with a flag per bit, a colour with red, green and blue squeezed into 16 bits, a character code whose bits mean something. Bitwise operations work on those bits directly. This lesson uses them to pick bytes apart, then looks at characters, where the same tricks turn a digit character into its value.
- AND, OR and XOR on whole bytes
- Shifts
- Characters
- A digit as a character and as a number
Or do it in the simulator, with tasks that mark themselves
Lessons that teach it
- A7.5 Bitwise operations and characters Data representation
Masks with AND, OR and XOR, logical, arithmetic and circular shifts, and characters as codes in ASCII and Unicode.
Try it on a robot
The task from A7.5 Bitwise operations and characters, running here. Change the program and press Run.
The specification is AQA's own document; this page says which of our lessons teach point 4.5.5.2 and is not endorsed by the board.