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Cambridge IGCSE GCSE Computer Science

Cambridge: Software, the internet and security — Cambridge IGCSE GCSE Computer Science revision

Free revision notes, key terms, common exam traps and 5 practice questions with answers. About 8 minutes to read.

Software and translators

  • System software (operating system, utilities, device drivers) manages hardware; application software (word processors, browsers) helps users complete tasks.
  • The operating system manages memory, files, processes, peripherals, security and the user interface. Interrupts signal that a device or program needs CPU attention, and the current state is saved before servicing them.
  • Translators: a compiler converts the whole program to machine code before execution and reports all errors together; an interpreter converts and runs line by line, stopping at the first error; assemblers translate assembly language. Integrated development environments provide editors, debuggers and error diagnostics.

The internet and its uses

  • The internet is the global network infrastructure; the World Wide Web is the collection of pages accessed over it. URLs contain protocol, domain name and file path, and DNS servers translate domain names into IP addresses.
  • Browsers render HTML, manage tabs, history, bookmarks and cookies. HTML structure defines content while CSS presentation defines style. HTTPS uses SSL/TLS with digital certificates to encrypt traffic.
  • Cloud storage offers access anywhere, automatic backup and scalability, but depends on internet access, raises privacy questions and involves ongoing cost.

Key terms

Operating system
System software managing hardware, files, memory and users.
Interrupt
A signal telling the CPU that a device or program needs attention.
Compiler
Translator converting a whole program into machine code before running.
Interpreter
Translator executing code line by line.
DNS
System translating domain names into IP addresses.
SSL/TLS
Protocols encrypting data between browser and server.

Common exam traps

  • Saying the internet and the World Wide Web are the same thing.
  • Confusing phishing (fake message) with pharming (redirection by malicious code).
  • Claiming a firewall removes viruses — it filters traffic; anti-malware removes infections.

Practice questions with answers

  1. 1. Which is system software?

    • • Spreadsheet
    • • Operating system
    • • Photo editor
    • • Web game

    Answer: Operating system

    System software manages the computer itself.

  2. 2. Give two tasks performed by an operating system.

    Answer: Memory management and file management (also peripherals, security, user interface)

    Any two management roles are creditable.

  3. 3. An interrupt causes the CPU to:

    • • Shut down
    • • Save its current state and service the request
    • • Delete data
    • • Compile code

    Answer: Save its current state and service the request

    It resumes afterwards from the saved state.

  4. 4. Give one advantage of a compiler over an interpreter.

    Answer: The compiled program runs faster and can be distributed without source code

    Interpreters are better for step-by-step debugging.

  5. 5. DNS servers:

    • • Store web pages
    • • Translate domain names into IP addresses
    • • Encrypt traffic
    • • Block malware

    Answer: Translate domain names into IP addresses

    They allow human-readable addresses.

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