AQA 7517 4.7.3.3: The processor instruction set
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
At GCSE you learned that a processor runs machine code. At A level you need to know what a machine code instruction is made of, why code for one processor will not run on another, and how the operand of an instruction can be used in different ways, called addressing modes. Addressing modes are what let a short instruction reach any value in memory, and they are how arrays and pointers work underneath.
- The instruction set
- Opcode and operand
- Addressing modes
- Indexed addressing walks an array
Or do it in the simulator, with tasks that mark themselves
Lessons that teach it
- A9.4 Instruction sets and addressing modes Computer architecture
Opcodes, operands and instruction formats; immediate, direct, indirect and indexed addressing.
Try it on a robot
The task from A9.4 Instruction sets and addressing modes, running here. Change the program and press Run.
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