Computer-science_A-level_Cie
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computers-and-components6 主题
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logic-gates-and-logic-circuits2 主题
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central-processing-unit-cpu-architecture6 主题
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assembly-language-4 主题
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bit-manipulation1 主题
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operating-systems3 主题
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language-translators2 主题
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data-security3 主题
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data-integrity1 主题
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ethics-and-ownership3 主题
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database-concepts3 主题
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database-management-systems-dbms-1 主题
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data-definition-language-ddl-and-data-manipulation-language-dml1 主题
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computational-thinking-skills1 主题
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algorithms14 主题
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data-types-and-records2 主题
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arrays2 主题
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files1 主题
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introduction-to-abstract-data-types-adt1 主题
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programming-basics1 主题
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constructs2 主题
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structured-programming1 主题
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program-development-life-cycle2 主题
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program-design-2 主题
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program-testing-and-maintenance3 主题
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user-defined-data-types1 主题
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file-organisation-and-access-3 主题
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floating-point-numbers-representation-and-manipulation3 主题
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protocols2 主题
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circuit-switching-packet-switching1 主题
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processors-parallel-processing-and-virtual-machines5 主题
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boolean-algebra-and-logic-circuits4 主题
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purposes-of-an-operating-system-os3 主题
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translation-software3 主题
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encryption-encryption-protocols-and-digital-certificates3 主题
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artificial-intelligence-ai4 主题
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recursion1 主题
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programming-paradigms4 主题
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object-oriented-programming7 主题
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file-processing-and-exception-handling2 主题
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data-representation5 主题
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multimedia3 主题
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compression2 主题
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networks-and-the-internet11 主题
the-internet
Internet vs WWW
What is the Internet?
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The Internet is a global network of networks (Interconnected Network)
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The Internet is the most well-known Wide Area Network (WAN)
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The Internet is the infrastructure used to provide connectivity to the World Wide Web (WWW)
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Uses protocols like TCP/IP to transfer data between devices and networks
What is the World Wide Web (WWW)?
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The world wide web, or simply the web, is a collection of websites and web pages that are accessed using the Internet
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It was created in 1989 by Tim Berners-Lee, who envisioned it as a way to share and access information on a global scale
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The web consists of interconnected documents and multimedia files that are stored on web servers around the world
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Web pages are accessed using a web browser, which communicates with web servers to retrieve and display the content
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Uses protocols like HTTP and HTTPS to request and deliver web content
Internet hardware
Modem
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Modem stands for modulator-demodulator
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Converts digital signals from a computer into analogue signals to send over telephone or cable lines
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Also converts analogue signals back into digital so the computer can understand them
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Allows devices to connect to the internet through technologies like:
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DSL
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Cable
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Dial-up
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Used to send and receive data over long distances via traditional communication lines
Public Switched Telephone Network (PSTN)
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Developed soon after the invention of the telephone in the late 1800s
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Originally built to handle voice communication over copper wires
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As the demand for other forms of communication grew, the PSTN was adapted to enable internet access
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Used to connect computers/devices and LANs between towns and cities
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Traditional copper telephone lines are being slowly replaced with fibre optic cables
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Fibre gives access to higher bandwidth and faster data transfer speeds
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Dedicated lines
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Dedicated lines (e.g. T1, T3, and fibre-optic) provide exclusive, high-speed connections between two points
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Unlike the PSTN, these connections are always active and not shared with other users
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Faster and more reliable
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Ideal for businesses and organisations needing consistent, high-bandwidth internet
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Better for activities like video conferencing, cloud computing, and large file transfers
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|
Connection type |
Speed |
|---|---|
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T1 Line |
Up to 1.54 Mbps |
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T3 Line |
Up to 45 Mbps |
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Fibre-Optic |
Speeds in the gigabits |
Cellular networks
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Provide wireless communication for mobile phones and other portable devices
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The network is made up of cells, each served by a cell tower (base station)
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Devices connect to the nearest tower to send and receive signals
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As a user moves, their device automatically switches to the next closest tower (handover)
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Used for voice calls, text messaging, and mobile data (internet access)
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Support different generations of mobile technology:
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2G – Basic calls and texts
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3G – Mobile internet and video calling
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4G – Fast internet browsing and streaming
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5G – Very high-speed internet, low latency (great for gaming and real-time apps)
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Responses