A Level Computer Science WJEC

This subject is broken down into 66 topics in 17 modules:

  1. Hardware and Communication 8 topics
  2. Logical Operations 1 topics
  3. Data Transmission 2 topics
  4. Data Representation and Data Types 4 topics
  5. Data Structures 1 topics
  6. Organisation of Data 4 topics
  7. Database Systems 1 topics
  8. The Operating System 6 topics
  9. Algorithms and Programs 14 topics
  10. Principles of Programming 3 topics
  11. Systems Analysis 8 topics
  12. Software Engineering 1 topics
  13. Program Construction 1 topics
  14. Different Types of Software Systems 3 topics
  15. Practical Programming 3 topics
  16. Data Security and Integrity Processes 3 topics
  17. Economic, Moral, Legal, Ethical and Cultural Issues 3 topics
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  • 17
    modules
  • 66
    topics
  • 25,343
    words of revision content
  • 3+
    hours of audio lessons

This page was last modified on 28 September 2024.

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Computer Science

Hardware and Communication

Hardware and Communication

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Hardware and Communication

Hardware

  • Processors: Central Processing Units (CPUs) are essential for executing program instructions. They perform arithmetic, logical, control and input/output operations within a computer system.
  • Main Memory: RAM (Random Access Memory) is vital for temporarily holding data and program instructions that the CPU uses frequently. ROM (Read Only Memory) is the non-volatile part of the main memory which retains data when power is switched off.
  • Secondary Memory: This includes hard disks, optical disks and solid state drives. They provide long-term storage of files and programs.
  • Input/Output Devices: These peripherals (e.g. keyboards, mice, monitors, printers) send and receive data to and from the computer system.
  • Buses: Connect all components in a computer system allowing data to be transmitted.
  • Understand the Von Neumann architecture. It's a computer design model where the storage and the processor share the same memory space.
  • Also comprehend the Fetch-Decode-Execute cycle that underpins how any computer works.

Communication

  • Understand network topologies like Star, Bus, Ring and Mesh. They're important for knowing how devices are connected in a network.
  • Know the different types of networks: Local Area Network (LAN), Wide Area Network (WAN), Metropolitan Area Network (MAN), and Personal Area Network (PAN).
  • Learn about network protocols (e.g. HTTP, FTP, TCP/IP, SMTP, POP3, IMAP). They govern how data is transferred across a network.
  • Identify the difference between routable and non-routable protocols.
  • Be familiar with the Client-Server model where servers provide resources and services to clients.
  • Get to know about Peer-to-Peer networking which allows resources sharing among network devices without the need of a central server.
  • Understand the concept of Virtual Networks and their benefits: e.g. VPNs that provide privacy and greater security online.
  • Grasp how cloud computing provides on-demand network access to shared computing resources.
  • Have a clear concept of hardware and software firewalls, which are instrumental for network security.

Course material for Computer Science, module Hardware and Communication, topic Hardware and Communication

Computer Science

Algorithms and Programs

Sorting

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Sorting

Overview of Sorting

  • Sorting is a process of arranging items in a certain order, which can be either ascending or descending.
  • Sorting helps achieve sorted data, which is efficient and faster to process for search operations and data analytics.

Common Sorting Algorithms

  • Bubble Sort: an algorithm that works by repeatedly swapping the adjacent elements if they are in the wrong order.
  • Insertion Sort: a simple sorting algorithm that builds the final sorted array (or list) one item at a time.
  • Selection Sort: an algorithm that sorts an array by repeatedly finding the minimum (considering ascending order) from unsorted part and putting it at the beginning.
  • Quick Sort: a divide and conquer algorithm that uses a pivot element to divide the array into two parts and then sorts them independently.
  • Merge Sort: another divide-and-conquer, comparison-based algorithm which is not in-place (uses extra space) but is stable and has a worst-case and average complexity of O(n log n).

Comparison of Sorting Algorithms

  • Sorting algorithms are often compared based on their time complexity, space complexity, and whether they are stable (two keys with equal values appear in the same order in output as they appear in input).
  • Bubble sort, insertion sort, and selection sort have an average and worst-case time complexity of O(n^2), making them less efficient on large lists, and are not used often for large data sets.
  • Quick sort is one of the fastest sorting algorithms for large datasets, though its worst-case performance is O(n^2). It is not a stable sort.
  • Merge sort is more efficient than bubble, insertion, and selection sort for larger lists as it always performs at O(n log n), and is a stable sort. However, it requires extra space, making it less efficient space-wise.

Role of Sorting in Programming

  • Sorting plays a crucial role in algorithms that involve searching, as a sorted dataset is much easier to search.
  • Applications include database sort/search operations, sorting data for analytics, algorithms in graphics engines to determine render orders, etc.
  • In computer programming, sorting algorithms are implemented through built-in library functions and custom algorithms depending on the specific requirements of the task.

Course material for Computer Science, module Algorithms and Programs, topic Sorting

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