IB Computer Science HL · Year 2 · Lesson 33
Operating systems: roles, functions and scheduling
Operating systems coordinate resources and processes; control systems sense, decide and act in the physical world.
Paper 150 minutesA1.3.1 · A1.3.2 · A1.3.3
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Today’s targets
What you need to be able to do
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- DescribeThe role of operating systems
- DescribeThe functions of an operating system
- CompareDifferent approaches to scheduling
A1.3.1A1.3.2A1.3.3
Paper 1 lensMatch the depth of every response to the command term. Previously learned content can move quickly, but retrieval must still be accurate.
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Retrieve
Rapid Recall Deck
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Say the answer aloud before flipping. Mark secure knowledge quickly and spend time on the gaps.
- What is the core role of an operating system?: It abstracts hardware complexity and manages computer resources so applications can run safely and efficiently.
- What major functions can an operating system perform?: Memory management, file system, device management, scheduling, security, accounting, GUI, virtualization, and networking.
- What is the purpose of CPU scheduling?: To decide which ready process receives CPU time and in what order so system goals such as responsiveness or throughput can be met.
- How does first-come, first-served scheduling work?: Processes are handled in the order they enter the ready queue.
- How does round-robin scheduling work?: Each ready process receives a time slice in turn, then returns to the queue if it has not finished.
- How do priority and multilevel-queue scheduling differ from simple FCFS?: They choose work based on priority or category/queue rather than only arrival order.
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A1.3.1 + A1.3.2 · Learn
Core knowledge and application
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A1.3.1Describe
The role of operating systems
Operating systems coordinate resources and processes; control systems sense, decide and act in the physical world.
Exam moveGive a detailed, accurate account of what happens or what something is like.
Required detail 1Operating systems abstract hardware complexities to manage system resources
Explain it without notes
Describe: The role of operating systems in the context of a computer running many tasks while controlling a smart device.
- Operating systems abstract hardware complexities to manage system resources
A1.3.2Describe
The functions of an operating system
Operating systems coordinate resources and processes; control systems sense, decide and act in the physical world.
Exam moveGive a detailed, accurate account of what happens or what something is like.
Required detail 1Maintaining system integrity while running operating systems’ background operations
Required detail 2Memory management, file system, device management, scheduling, security, accounting, graphical user interface (GUI), virtualization, networking
Explain it without notes
Describe: The functions of an operating system in the context of a computer running many tasks while controlling a smart device.
- Maintaining system integrity while running operating systems’ background operations
- Memory management, file system, device management, scheduling, security, accounting, graphical user interface (GUI), virtualization, networking
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A1.3.3 · Learn
Core knowledge and application
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A1.3.3Compare
Different approaches to scheduling
Operating systems coordinate resources and processes; control systems sense, decide and act in the physical world.
Exam moveMake direct, paired comparisons using the same criteria.
Required detail 1Managing the execution of processes by allocating CPU time to optimize system performance
Required detail 2First-come first-served, round robin, multilevel queue scheduling, priority scheduling
Explain it without notes
Compare: Different approaches to scheduling in the context of a computer running many tasks while controlling a smart device.
- Managing the execution of processes by allocating CPU time to optimize system performance
- First-come first-served, round robin, multilevel queue scheduling, priority scheduling
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Apply
Transfer to a new scenario
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ScenarioA computer running many tasks while controlling a smart device needs a design or technical decision related to today’s topic. Explain what matters and why.
- Operating systems abstract hardware complexities to manage system resources
- Maintaining system integrity while running operating systems’ background operations
- Memory management, file system, device management, scheduling, security, accounting, graphical user interface (GUI), virtualization, networking
- Managing the execution of processes by allocating CPU time to optimize system performance
- First-come first-served, round robin, multilevel queue scheduling, priority scheduling
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Exam lens
Paper 1 practice
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Build the response before checking notesUse precise terminology and match the required depth.
- Describe: The role of operating systems in the context of a computer running many tasks while controlling a smart device.
- Describe: The functions of an operating system in the context of a computer running many tasks while controlling a smart device.
- Compare: Different approaches to scheduling in the context of a computer running many tasks while controlling a smart device.
Self-checkAnswer the exact command term. For explain, include mechanism/reason; for compare, pair criteria; for discuss/evaluate/justify, build supported reasoning and a conclusion.
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Homework
Finish the learning cycle
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IA — main task
Finish Criterion D evidence: development documentation, testing evidence, video planning/recording and full source-code appendix.
Syllabus — short
Complete a short Paper 1 retrieval set based on today’s topic.
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End of Lesson 33.