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Computer-science_A-level_Cie

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  1. computers-and-components
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  2. logic-gates-and-logic-circuits
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  3. central-processing-unit-cpu-architecture
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  4. assembly-language-
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  5. bit-manipulation
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  6. operating-systems
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  7. language-translators
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  8. data-security
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  9. data-integrity
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  10. ethics-and-ownership
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  11. database-concepts
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  12. database-management-systems-dbms-
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  13. data-definition-language-ddl-and-data-manipulation-language-dml
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  14. computational-thinking-skills
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  15. algorithms
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  16. data-types-and-records
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  17. arrays
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  18. files
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  19. introduction-to-abstract-data-types-adt
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  20. programming-basics
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  21. constructs
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  22. structured-programming
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  23. program-development-life-cycle
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  24. program-design-
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  25. program-testing-and-maintenance
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  26. user-defined-data-types
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  27. file-organisation-and-access-
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  28. floating-point-numbers-representation-and-manipulation
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  29. protocols
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  30. circuit-switching-packet-switching
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  31. processors-parallel-processing-and-virtual-machines
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  32. boolean-algebra-and-logic-circuits
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  33. purposes-of-an-operating-system-os
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  34. translation-software
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  35. encryption-encryption-protocols-and-digital-certificates
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  36. artificial-intelligence-ai
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  37. recursion
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  38. programming-paradigms
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  39. object-oriented-programming
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  40. file-processing-and-exception-handling
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  41. data-representation
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  42. multimedia
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  43. compression
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  44. networks-and-the-internet
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Standard protocols

  • A protocol is a set of rules that govern communication on a network

  • There are protocols for different purposes, such as:

    • HTTP & HTTPS

    • FTP

    • POP, IMAP & SMTP

    • BitTorrent

HTTP & HTTPS

  • Hypertext Transfer Protocol (HTTP) allows communication between clients and servers for website viewing

  • HTTP allows clients to receive data from the sever (fetching a webpage) and send data to the server (submitting a form, uploading a file)

  • HTTPS works in the same way as HTTP but with an added layer of security

  • All data sent and received using HTTPS is encrypted

  • HTTPS is used to protect sensitive information such as passwords, financial information and personal data

http

FTP

  • File Transfer Protocol (FTP) allows sending and receiving files between computers

  • Uploading and downloading files to/from a web server is often completed using FTP

  • FTP offers greater efficiency and support for bulk transfers and large files such as resuming interrupted transfers

  • FTP clients are software applications that use the FTP protocol to make the process easier for users

ftp

POP, IMAP & SMTP

  • A family of protocols that handle sending and receiving of email across the internet (WAN)

imapi-1

SMTP

  • Simple Mail Transfer Protocol (SMTP) is a protocol that allows communication between an email sender and the email server, and between different email servers using the internet

  • In the diagram above, SMTP is used to transfer the senders email to their email providers server and SMTP is used to transfer the email to the recipients email server

POP

  • Post Office Protocol (POP) is a protocol for downloading emails to a device from an email server

  • Once the email has been retrieved it is removed from the server

IMAP

  • Internet Message Access Protocol (IMAP) is a protocol for downloading emails to a device from an email server

  • Once the email has been retrieved, a copy is retained on the mail server

Advantages & disadvantages of POP/IMAP

 

Advantages

Disadvantages

POP

  • Frees up storage space on email servers

  • Faster on slow connections

  • Only access emails from the device they’re downloaded to

  • Emails deleted on the server once downloaded

IMAP

  • View and manage emails from any device with internet access

  • Changes made on one device are synchronised on all connected devices

  • Server storage space can limit amount of retained emails

  • Requires internet access to view emails

BitTorrent

  • BitTorrent is a peer-to-peer (P2P) file-sharing protocol used to distribute large amounts of data efficiently across the internet

  • Instead of downloading a file from a single central server, BitTorrent allows users to download pieces of the file from multiple users (peers) who already have parts of it

  • This makes file sharing:

    • Faster, as downloads come from many sources at once

    • More efficient, as it reduces the load on any single server

  • BitTorrent is often used for:

    • Sharing large files, such as software, videos, or games

    • Decentralised distribution, which avoids the need for central hosting

  • While BitTorrent is a legal technology, it is sometimes used for sharing copyrighted content illegally, so ethical and legal use is important

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