A1.1 Computer hardware and operation: notes and practice

What you need to know

Our summary of the topic in our own words, not the IB guide. Points marked HL are for Higher Level only.

• Name the main components of a CPU and state what each one does
• Explain how the control unit, ALU and registers interact to execute an instruction
• Describe the purpose of the address bus, data bus and control bus
• Explain the role of specific registers such as the program counter, instruction register and memory address register
• Compare single-core and multi-core processors and explain why core count alone does not determine performance
• Describe what a GPU is and the kinds of work it is designed for
• Give real examples of GPU workloads such as graphics rendering, simulation and neural network training
• Compare CPU and GPU architecture in terms of core count, instruction handling and memory accessHL
• Explain why a GPU suits high-throughput parallel work and a CPU suits low-latency sequential workHL
• Distinguish RAM from ROM and state what each is used for
• Place registers, cache, main memory and secondary storage in order of speed, size and cost
• Explain what cache memory is for and what a cache hit and a cache miss mean
• Describe the fetch, decode and execute cycle step by step
• Trace which registers and buses are used at each stage of the cycle for a given instruction
• Explain pipelining and how overlapping instruction stages raises throughputHL
• Describe how pipelining applies in a multi-core architecture and what can stall a pipelineHL
• Compare internal and external secondary storage types including HDD, SSD, optical, flash and network attached storage
• Choose an appropriate storage type for a given scenario and justify it on capacity, speed, durability and cost
• Distinguish lossy from lossless compression and say when each is appropriate
• Apply run-length encoding to a small data set by hand
• Describe how a dictionary-based compression scheme such as LZW builds and uses its dictionary
• Distinguish the cloud service models SaaS, PaaS and IaaS with an example of each
• Compare cloud and on-premises provision on cost, control, scalability and security

Practice questions

Original questions written for the 2027 course, marked as you go. Easiest first.

• ALU and program counter in a CPUWritten · Warm-up
• How CPU cache memory speeds up a loopWritten · Core
• SSD or HDD for an outdoor computerWritten · Core
• Fetch-decode-execute cycle for LOADWritten · Stretch
• CPU pipelining and clock cyclesWritten · Stretch

Exam tips for A1.1

• Learn the fetch, decode and execute cycle as a sequence, naming the register or bus used at each step. Practise it until you can write it from memory.
• When comparing storage, give a reason tied to the scenario (cost, speed, durability or capacity), not just a list of features.
• Practise run-length encoding by hand on a short string. It is quick marks if you are careful.