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Craig 'n' Dave · Edexcel 1CP2Operating Systems
Key facts
Core OS functions
- Process management / multitasking — manages multiple processes, gives each a time slice, switches between them (scheduling)
- Memory management — allocates RAM to processes, prevents processes accessing each other's memory
- File management — organises files in a hierarchical directory structure, controls read/write access
- Peripheral management — communicates with hardware devices via device drivers
- User management — controls user accounts, permissions and access rights
- User interface — provides CLI (command line) or GUI (graphical) interface
Scheduling — how multitasking works
- CPU can only run one process at a time — scheduling gives the illusion of simultaneous execution
- A scheduler controls which process runs and for how long
- Each process gets a time slice — a small amount of CPU time
- Processes are held in a queue (data structure)
- Incomplete processes go to the back of the queue
- Priority scheduling: higher-priority processes get more/longer time slices
Utility software
- Defragmentation — reorganises fragmented files on magnetic drives to improve read speed
- Anti-malware — detects and removes malicious software
- Backup software — creates copies of data to prevent loss
- Compression software — reduces file size for storage or transfer
- Firewall — monitors network traffic against a rule set
- Disk formatting — prepares a storage device for use
Exam questions — 4 questions · 9 marks · from real 1CP2 past papers
1 markOS scheduling1CP2 Jun 2023 Q1(g)(i) style
How does an operating system allow multiple processes to appear to run simultaneously on a single CPU?
A It installs a second CPU to handle additional processes
B A scheduler gives each process a time slice of CPU time, switching rapidly between processes and holding incomplete ones in a queue
C It stores all processes in cache so they can all be accessed at once
D It runs each process fully before starting the next
1 markUtility software1CP2 Jun 2023 Q1(g)(ii) style
Which of the following is a function of the operating system?
A Editing a spreadsheet document
B Compiling a Python program
C Managing user accounts and access permissions
D Sending an email
2 marksUser management1CP2 Jun 2022 Q2(g) style
Explain how the operating system's user management function benefits users of a shared computer. (2 marks)
Hint: Give a feature (what it does) AND a benefit (why it helps users of a shared machine).
+20 XP
2 marksDefragmentation1CP2 style
Explain what defragmentation does and why it is only necessary for magnetic hard drives, not SSDs. (2 marks)
Hint: Explain what defrag does + why it helps HDDs + why SSDs don't need it.
+20 XP
Module complete! 🎉
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