Computer Science

Key Facts

• Paper 1 and Paper 2 are both 1 hour 30 minutes and 100 marks.
• Use precise technical vocabulary and avoid vague statements.
• Most 6-9 mark questions require structure and evaluation.
• Draw clear diagrams for networks and CPU architecture.

Subtopics

Key Facts

• Selection uses IF/ELSE logic; iteration uses loops.
• Binary search requires sorted data.
• Merge sort is faster on large data sets.
• Flowcharts and pseudocode should follow standard conventions.

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Key Facts

• Indentation improves readability and reduces errors.
• Syntax errors stop a program from running.
• Logic errors produce incorrect output with no crash.
• Good algorithms can be expressed in pseudocode or flowcharts.

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Key Facts

• 1 byte = 8 bits; 1 KB = 1024 bytes.
• Higher resolution increases file size.
• Sampling theorem: sample at least twice the highest frequency.
• Hex is base 16 and uses 0-9 and A-F.

Subtopics

Key Facts

• Indexing often starts at 0 in many languages.
• Stacks are used in function call handling.
• Queues are used for task scheduling.

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Key Facts

• Clock speed and number of cores affect CPU performance.
• RAM is cleared when power is off.
• Virtual memory uses secondary storage to extend RAM.
• SSDs are faster and more durable than HDDs.

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Key Facts

• MAC addresses identify devices on a LAN.
• IP addresses identify devices on a network.
• DNS turns domain names into IP addresses.
• Packets contain header, payload, and trailer data.

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Key Facts

• Phishing uses fake messages to steal data.
• Strong passwords combine length, symbols, and unpredictability.
• Brute force attacks try every possible password.
• Two-factor authentication adds a second layer of security.

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Key Facts

• Databases improve data accuracy and reduce duplication.
• Validation checks data type, range, or format.
• Verification ensures data is entered correctly.

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Key Facts

• Normal test data is within expected range.
• Boundary data tests limits of the range.
• Erroneous data checks validation and error handling.

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Key Facts

• Data must be processed securely and for specific purposes.
• Copyright protects software and digital content.
• Open source allows modification and sharing.

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