Paper 1

• Types of processors:

  • CISC (Complex Instruction Set Computing): supports more instructions, more transistors and power, less complicated software
  • RISC (Reduced Instruction Set Computing): supports fewer instructions, fewer transistors and power, more complicated software
  • GPUs: designed for graphics, example of array processor
• Types of operating systems:

  • Multitasking operating system: allows the user to do multiple things at the same time
  • Multi-user operating system: allows users to share resources of one powerful machine
  • Distributed operating system: runs across multiple individual computers but appears as one system to the end user
  • Embedded OS: found in hardware serving a single purpose
  • Real-time operating system: reacts to input as close to real time as possible
• Device drivers: contain software that tells the operating system how to understand data from external hardware devices and the format it expects to receive the data in

  • BIOS: basic input output system that controls the computer's startup sequence and helps configure hardware devices
  • Virtual machines (VM): program designed to fully simulate a computer in software, allowing multiple operating systems to run on the same computer or server
• Applications:

  • Application software: allows users to perform tasks or produce something (e.g., word processor, spreadsheet, web browser)
  • Utility: small program with one purpose, usually for system maintenance (e.g., disk cleanup, defragmenter, compression, encryption)
  • Open source vs. closed source software:
  • Open source: source code available, often free and can be amended by users
  • Closed source: proprietary source code not available, usually more polished and easier to install with customer support
• Translators:

  • Assembler: converts assembly code into machine code
  • Interpreter: converts high-level source code into machine code line by line
  • Compiler: converts high-level source code into machine code all at once
• Software development lifecycle methodologies:

  • Waterfall model: sequential stages followed linearly, suited for large-scale projects with stable requirements
  • Rapid Application Development (RAD): builds a prototype evaluated and refined over multiple iterations, well-suited for projects with unclear requirements
  • Spiral model: manages risk well, requires risks to be identified and evaluated at each stage, suitable for large-scale or risky projects
  • Agile software development: deals with changing requirements, Extreme Programming (XP) focuses on producing high-quality code
• Types of programming languages:

  • Low-level vs. high-level languages
  • Low-level languages: machine code, Assembly Language
  • High-level languages: imperative (procedural, object-oriented), declarative (logic, functional)
• Assembly Language:

  • Uses mnemonics to represent machine code instructions
  • Little Man Computer instruction set for basic understanding
• Modes of addressing memory:

  • Immediate addressing: data hard-coded into the instruction
  • Direct addressing: operand contains memory address
  • Indirect addressing: address of data held in an intermediate location
  • Indexed addressing: final address determined by adding an offset to a base address
• Object-oriented languages:

  • Object-oriented programming (OOP) organizes programs around data or objects
  • Classes: templates defining attributes and methods for objects
  • Encapsulation, inheritance, polymorphism for code reuse and maintenance
• Abstraction: objects reveal only relevant internal mechanisms

  • Encapsulation: implementation and state of each object can be private
• Encapsulation:

  • Implementation and state of each object can be private
  • Provides greater program security and avoids unintended data corruption
• Inheritance:

  • Define a class which inherits attributes and methods from a parent class
  • Encourages code reuse and programming
• Polymorphism:

  • Ability to use the same code to process different objects according to their type
  • Program determines the meaning your usage is necessary for each execution of that object
• Compression:

  • Types: lossy compression and lossless compression
  • Lossy compression removes data to reduce file sizes, resulting in reduced quality
  • Lossless compression has no data loss and is reversible
• Run Length Encoding (RLE):

  • Replaces repeating consecutive sequence of data with a single data value
  • Works best with long sequences of the same data
• Dictionary Coding:

  • Uses redundant repeated data to store data items once in a dictionary
  • Best for long files with lots of repeated data
• Symmetric Encryption:

  • Uses the same key to encrypt and decrypt the message
  • Works well when the key can be securely passed
• Asymmetric Encryption:

  • Uses two different keys for encryption and decryption
  • Better for use across the internet where keys cannot be physically exchanged
• Hashing:

  • Generates a value from a string of text using a mathematical function
  • One-way process that scrambles data
• Database:

  • Structured collection of data
  • Flat file database vs relational database
  • Primary key, foreign key, secondary key, entity relationship diagram
• Normalization:

  • Process of organizing data into tables in a series of steps
  • Zero, first, second, and third normal form
  • Eliminating data redundancy and ensuring data integrity
• SQL:

  • Basic code structure: SELECT, FROM, WHERE
  • Use of wildcards and percentage sign for complex queries
  • Select statements within select statements for nested queries
  • Join keyword to link tables with foreign keys
• Foreign keys link fields in different tables with the same information
• Example: SELECT student.surname, course.name FROM student JOIN course ON student.course ID = course.course ID
• Transaction processing involves changes to the database from one consistent state to another
• ACID rules for database integrity:

  • Atomicity: transaction must be completed fully
  • Consistency: any change must not break the database
  • Isolation: a transaction must be isolated and not interfere with another transaction
  • Durability: a transaction must remain in the database
• Data integrity ensures accuracy and reliability of data in a computer system
• Referential integrity ensures consistency in the database with matching foreign keys to primary keys
• Record locking is used to lock a table until a transaction is completed
• Redundancies are built into database systems for organizations like hospitals, military forces, and banks to prevent catastrophic system failure
• Networks are collections of connected computer devices used for communication and data sharing
• Network hardware includes NIC, switch, wireless access point, router, copper cables, fiber optic cables, and radio waves
• Networks can be classified by extent (LAN, WAN, PAN), topology (bus, ring, star, mesh), and protocols (TCP, IP, HTTP, HTTPS, FTP, SMTP, POP, IMAP)
• Network communication is complex and uses layering with different protocols for different aspects of functionality
• TCP/IP model includes application layer, transport layer, internet layer, and network/link layer
• DNS matches domain names to IP addresses using domain name servers
• Circuit switching establishes a physical connection, while packet switching divides messages into packets for modern computer networks
• Authentication methods include usernames/passwords, two-factor authentication, and biometric information
• Firewalls monitor and filter data coming into and out of the network for security