GCSE Computer Science (J277)

1.1.1 Systems Architecture

• The purpose of the CPU: The Fetch-Execute cycle
• Common CPU components and their function: ALU, CU, Cache, Registers
• Von Neumann architecture: MAR, MDR, Program Counter, Accumulator

1.1.2 CPU performance

• How common characteristics of CPUs affect their performance: Clock speed, Cache size, Number of cores

1.1.3 Embedded Systems

• The purpose and characteristics of embedded systems
• Examples of embedded systems

1.2.1 Primary Storage (memory)

• The need for primary storage
• The difference between RAM and ROM
• The purpose of ROM in a computer system
• The purpose of RAM in a computer system
• Virtual memory
• Cache memory

1.2.2 Secondary Storage

• The need for secondary storage
• Common types of storage: Optical, Magnetic, Solid State
• Suitable storage devices and storage media for a given application
• The advantages and disadvantages of different storage devices and storage media relating to these characteristics: Capacity, speed, portability, durability, reliability, cost

1.2.3 Units

• The units of data storage: Bit, Nibble, Byte, KB, MB, GB, TB, PB
• How data needs to be converted into a binary format to be processed by a computer
• Data capacity and calculation of data capacity requirements

1.2.4a Data Storage: Numbers

• Numbers: How to convert positive denary whole numbers to binary numbers (up to and including 8 bits) and vice versa
• Numbers: How to add two binary integers together (up to and including 8 bits) and explain overflow errors which may occur
• Numbers: How to convert positive denary whole numbers into 2-digit hexadecimal numbers and vice versa
• Numbers: How to convert binary integers to their hexadecimal equivalents and vice versa
• Numbers: Binary shifts

1.2.4b Data Storage: Characters

• Calculate file sizes of text
• Characters: The use of binary codes to represent characters
• Characters: The term 'character set'
• Characters: The relationship between the number of bits per character in a character set, and the number of characters which can be represented, e.g. ASCII, Unicode

1.2.4c Data Storage: Images

• Calculate file sizes of image
• Images: How an image is represented as a series of pixels, represented in binary
• Images: Metadata
• Images: The effect of colour depth and resolution on:quality of the image, size of an image file

1.2.4d Data Storage: Sound

• Calculate file sizes of sound
• Sound: How sound can be sampled and stored in digital form
• Sound: The effect of sample rate, duration and bit depth on: playback quality, size of the sound file

1.2.5 Compression

• The need for compression
• Types of compression: Lossy, Lossless

1.3.1 Networks and topologies

• Types of network: LAN (Local Area Network), WAN (Wide Area Network)
• Factors that affect the performance of networks
• The different roles of computers in a client-server and a peer-to peer network
• The hardware needed to connect stand-alone computers into a Local Area Network: Wireless access points, Routers, Switches, NIC (Network Interface Controller/Card), Transmission media
• The Internet as a worldwide collection of computer networks: DNS (Domain Name Server), Hosting, The Cloud, Web servers and clients
• The Internet: DNS (Domain Name Server)
• The Internet: Hosting
• The Internet: The cloud
• The Internet: Web servers and clients
• Star and Mesh network topologies

1.3.2 Wired and wireless networks, protocols and layers

• Modes of connection: Wired - Ethernet; Wireless - Wi-Fi, Bluetooth;
• Encryption
• IP addressing and MAC addressing
• Standards
• Common protocols
• Common protocols: TCP/IP (Transmission Control Protocol/Internet Protocol)
• Common protocols: HTTP (Hyper Text Transfer Protocol)
• Common protocols: HTTPS (Hyper Text Transfer Protocol Secure)
• Common protocols: FTP (File Transfer Protocol)
• Common protocols: POP (Post Office Protocol)
• Common protocols: IMAP (Internet Message Access Protocol)
• Common protocols: SMTP (Simple Mail Transfer Protocol)
• The concept of layers

1.4.1 Threats to computer systems and networks

• Forms of attack
• Forms of attack: Malware
• Forms of attack: Social engineering, e.g. phishing, people as the 'weak point'
• Forms of attack: Brute-force attacks
• Forms of attack: Denial of service attacks
• Forms of attack: Data interception and theft
• Forms of attack: The concept of SQL injection

1.4.2 Identifying and preventing vulnerabilities

• Common prevention methods
• Common prevention methods: Penetration testing
• Common prevention methods: Anti-malware software
• Common prevention methods: Firewalls
• Common prevention methods: User access levels
• Common prevention methods: Passwords
• Common prevention methods: Encryption
• Common prevention methods: Physical security

1.5.1 Operating Systems

• The purpose and functionality of operating systems: User interface, Memory management and multitasking, Peripheral management and drivers, User management, File management
• The purpose and functionality of operating systems: User interface
• The purpose and functionality of operating systems: Memory management and multitasking
• The purpose and functionality of operating systems: Peripheral management and drivers
• The purpose and functionality of operating systems: User management
• The purpose and functionality of operating systems: File management

1.5.2 Utility software

• The purpose and functionality of utility software
• Utility system software: Encryption software; Defragmentation; Data compression

1.6.1 Ethical, legal, cultural and environmental impact

• Impacts of digital technology on wider society including: Ethical issues; Legal issues; Cultural issues; Environmental issues; Privacy issues
• Legislation relevant to Computer Science:The Data Protection Act 2018; Computer Misuse Act 1990; Copyright Designs and Patents Act 1988; Software licences (i.e. open source and proprietary)
• Legislation relevant to Computer Science: The Data Protection Act 2018
• Legislation relevant to Computer Science: Computer Misuse Act 1990
• Legislation relevant to Computer Science: Copyright Designs and Patents Act 1988
• Legislation relevant to Computer Science: Software licences (i.e. open source and proprietary)

2.1.1 Computational Thinking

• Principles of computational thinking: Abstraction; Decomposition; Algorithmic thinking.

2.1.2 Designing, creating and refining algorithms

• Identify the inputs, processes, and outputs for a problem
• Structure diagrams
• Create, interpret, correct, complete, and refine algorithms using: Pseudocode
• Create, interpret, correct, complete, and refine algorithms using: Flowcharts
• Create, interpret, correct, complete, and refine algorithms using: Reference language/high-level programming language
• Identify common errors
• Trace tables

2.1.3 Searching and sorting algorithms

• Standard searching algorithms: Binary search
• Standard searching algorithms: Linear search
• Standard sorting algorithms: Bubble sort
• Standard sorting algorithms: Merge sort
• Standard sorting algorithms: Insertion sort

2.2.1 Programming Fundamentals

• The use of variables, constants, operators, inputs, outputs and assignments
• The use of the three basic programming constructs used to control the flow of a program: Sequence
• The use of the three basic programming constructs used to control the flow of a program: Selection
• The use of the three basic programming constructs used to control the flow of a program: Iteration (count- and condition-controlled loops)
• The common arithmetic operators
• The common Boolean operators AND, OR and NOT

2.2.2 Data Types

• The use of data types
• Casting

2.2.3 Additional Programming Techniques

• The use of basic string manipulation: Concatenation
• The use of basic string manipulation: slicing
• The use of basic file handling operations: Open, Read, Write, Close
• The use of records to store data
• The use of SQL to search for data
• The use of arrays (or equivalent) when solving problems: one-dimensional (1D)
• The use of arrays (or equivalent) when solving problems: two-dimensional arrays(2D)
• How to use sub programs (functions and procedures) to produce structured code
• Functions and Procedures: local variables
• Functions and Procedures: global variables
• Functions and Procedures: arrays
• Random number generation

2.3.1 Defensive Design

• Defensive design considerations: Anticipating misuse, Authentication
• Input validation
• Maintainability: Use of sub programs; Naming conventions; Indentation; Commenting

2.3.2 Testing

• The purpose of testing
• Types of testing: Iterative, Final/terminal
• Identify syntax and logic errors
• Selecting and using suitable test data: Normal; Boundary; Invalid/Erroneous
• Refining algorithms

2.4.1 Boolean Logic

• Simple logic diagrams using the operators AND, OR and NOT
• Truth tables
• Combining Boolean operators using AND, OR and NOT
• Applying logical operators in truth tables to solve problems

2.5.1 Languages

• Characteristics and purpose of different levels of programming language: High-level languages; Low-level languages
• The purpose of translators
• The characteristics of a compiler and an interpreter

2.5.2 IDEs

• Common tools and facilities available in an Integrated Development Environment (IDE): Editors; Error diagnostics; Run-time environment; Translators

301.1 Output and Sequence

• Basic print / output
• Literals vs variables
• Sequence execution

301.2 Arithmetic Operators

• Arithmetic operators
• DIV and MOD
• Exponentiation
• Operator precedence

301.3 Variables and Constants

• Declare variables
• Constants
• Tracing variables
• Naming conventions

301.4 Data Types and Casting

• Common data types
• Choosing types
• Casting
• Fix type errors

301.5 Concatenation and Basic Strings

• String concatenation
• Strings + Numbers
• Readable output

301.6 Input

• Input basics
• Numeric input
• IPO Pattern

301.7 Maintainable Code

• Meaningful names
• Indentation
• Comments
• Tidy code comparison

301.8 Boolean Expressions

• Comparison operators
• Logical operators
• Translate logic

301.9 Selection

• IF and Else
• ELIF chains
• Nested IF
• Match Case

301.10 Iteration

• FOR loops
• WHILE loops
• Loop patterns
• Loop bugs

301.11 String Manipulation

• String length
• Substring slicing
• Case conversion
• String validation

301.12 Subprograms

• Why subprograms
• Procedures
• Functions
• Scope + parameters

301.13 Testing

• Why test?
• Test data types
• Dry run tracing
• Expected vs actual
• Test tables
• Debugging

301.14 Random Number Generation

• Random integers
• Games
• Off-by-one

301.15 File Handling Techniques

• Opening files
• Reading files
• Writing files
• Closing files

301.16 Defensive Design

• Anticipate misuse
• Validation checks
• Authentication
• Validation subprograms
• Error messaging

301.17 Arrays and Records

• 1D arrays
• 2D arrays
• Arrays in subprograms
• Records

301.18 IDE Skills

• Editor usage
• Error messages
• Running code
• Debugging tools