Pearson Edexcel International AS Level Information Technology - Complete Study Guide

Topic 1: Hardware and Software

Features and Functions of Devices

• Device Definition: An electronic piece of technology composed of physical hardware and internal software.

• Features: Distinctive characteristics or parts of a device (e.g., color, size, screen type).

• Functions: The intended purpose or way a device is used (e.g., making calls, gaming).

• Key Identification Attributes:

  • Portability: How easily a device can be carried. Smaller devices are generally more portable. Important for mobile phones/tablets; less critical for desktop PCs and smart TVs.

  • Performance: How well and fast a device works for its intended purpose (e.g., app opening speed).

  • Storage: Hardware used to store data (text, values, images, sound).

    • Magnetic Storage: Uses electromagnets and moving parts; prone to physical damage if dropped.

    • Solid-State Storage (SSD): Uses silicon chips and integrated circuits (IC). Faster, smaller, and more durable than magnetic storage.

    • RAID (Redundant Array of Independent Disks): Combining multiple storage devices for performance (RAID 0) or data protection/mirroring (RAID 1).

  • User Interface (UI): The medium through which a person interacts with the device (e.g., buttons, touchscreens, Graphical User Interface with windows/icons/menus).

  • Connectivity: Ability to connect to other devices via wired (USB, HDMI, VGA, DP) or wireless (Wi-Fi, Bluetooth, NFC) methods.

    • USB Standards: USB-C is the modern standard for power and speed; USB3 is faster than USB2.

  • Media Support: Capability to use formats like SD cards, flash memory, and optical disks (CD/DVD).

  • Energy Consumption: The amount of electricity used. Low consumption is preferred for battery life and environmental sustainability.

  • Expansion Capacity: The ability to add components (e.g., more RAM or storage) later.

  • Security Features: Includes passwords and Biometrics (using biological data like fingerprints or facial recognition).

Internal Components and Technologies

• Processor (CPU): Process all instructions. Performance is determined by:

  • Clock Speed: Measured in Gigahertz (GHz). $1\,GHz = 1\text{ billion instructions per second}$.

  • Cores: Number of instructions processed simultaneously (e.g., Dual-core).

• Memory:

  • ROM (Read Only Memory): Non-volatile storage for start-up instructions (BIOS).

  • RAM (Random Access Memory): Volatile storage for currently running programs and data.

• Sensors: Capture environmental data (Light, Accelerometers, Motion, Temperature).

• Embedded Systems: Systems with a dedicated purpose (e.g., smartwatches, washing machines) controlled by microprocessors.

• Technological Convergence: Combining multiple devices/services into one (e.g., Smartphone, Smart TV).

• Internet of Things (IoT): Everyday devices connected to the internet to share data.

• Firmware: Basic instructions for a system to function, containing the BIOS (initializes hardware) and Bootloader (loads the OS).

Data Representation and File Sizes

• Analogue vs. Digital: Humans process analogue (continuous) data; computers process digital (binary) data.

• Binary Conversions:

  • Denary to Binary: Based on multiples of 2. For 150:

    • $128 + 0 + 0 + 16 + 0 + 4 + 2 + 0 = 10010110_2$

  • Binary to Denary: Summing the value of positions marked with 1.

• Units of Measurement:

  • $1\text{ Nibble} = 4\text{ bits}$

  • $1\text{ Byte} = 8\text{ bits}$

  • $1\text{ Kibibyte (KiB)} = 1024\text{ bytes}$

  • $1\text{ Mebibyte (MiB)} = 1024\text{ KiB}$

  • $1\text{ Gibibyte (GiB)} = 1024\text{ MiB}$

• File Transfer Expression:

  • Time (seconds) for 10 MiB across a 10 gigabit ethernet connection:

  • $\frac{10 \times 8 \times 1024 \times 1024}{10 \times 1000 \times 1000 \times 1000}$

Topic 2: Networks

Network Components

• NIC (Network Interface Card): Essential for any device to connect to a network. Can be wired or wireless (WNIC).

• Hub: Basic connector that broadcasts data to every device on a LAN; causes high data collisions.

• Switch: Intelligent connector that uses MAC Addresses to send data only to the intended destination.

• Router: Forwards data packets between networks using IP Addresses and a routing table.

• Modem (Modulator-Demodulator): Converts between analogue (telephone wires) and digital signals.

• Gateway: Translates protocols between different network types (e.g., connecting a LAN to the Internet).

• Bridge: Connects two LANs to act as one large LAN.

• Repeater: Boosts weak electrical signals to allow long-distance transmission.

• Server: Central hardware providing data or services (file, web, or print servers).

• WAP (Wireless Access Point): Core hardware for receiving radio signals from wireless devices.

Transmission Media

• Wired:

  • Twisted Pair: Copper wires twisted together. Cheap, easy install, limited distance due to EMI. Speeds up to $10\,Gbps$.

  • Coaxial: Copper with a central wire and metal shield. Used for Cable TV. Less EMI prone.

  • Fibre Optic: Strands of glass/plastic using light signals. Expensive, high speed ($1\,Gbps+$), immune to EMI.

  • Powerline: Uses existing electrical wiring in a building.

• Wireless:

  • Microwaves: Point-to-point, unidirectional, high frequency, requires line of sight.

  • Radio Waves: Omnidirectional, can pass through walls; used for Wi-Fi.

  • Infrared: Very short distance, requires line of sight (e.g., TV remotes).

  • Satellite: Uses radio waves to communicate with Earth-based ground stations. Pinpoints location via Triangulation (min. 3 satellites).

Network Models and Protocols

• Client-Server: Central servers manage resources. High security and easy backups, but expensive/central failure point.

• Peer-to-Peer (P2P): All computers are equal peers. Cheap and easy but less secure and lacks central management.

• Ad Hoc: Spontaneous, temporary wireless network set up without a router.

• Tethering: Connecting a device to a mobile phone to use its internet, turning the phone into a Hotspot.

• The OSI Model (7 Layers):

  1. Application

  2. Presentation

  3. Session

  4. Transport

  5. Network

  6. Data Link

  7. Physical

• TCP/IP (4 Layers): Application, Transport, Network/Internet, Link/Physical.

• Addressing:

  • MAC Address: 48-bit hex unique ID assigned by the manufacturer (e.g., $3C:5A:84:01:63:02$).

  • IP Address: Software-assigned. IPv4 (32-bit, denary) vs. IPv6 (128-bit, hex).

Topic 3: The Online Environment

Web Technologies

• Internet vs. WWW: Internet is the infrastructure (cables, hardware); WWW is the collection of web pages viewed over the internet.

• DNS (Domain Name System): Translates text URLs (pearson.com) into matching binary IP addresses.

• Static Web Pages: Content remains the same for every user; run using client-side scripting (JavaScript).

• Dynamic Web Pages: Content is generated per request (personalised); requires server-side scripting (PHP).

• Scripting Location:

  • Client-side: Processing on user's browser (e.g., JavaScript).

  • Server-side: Processing on the web server (e.g., PHP). Source code is hidden from the user.

Online Interaction and Impact

• Online Working Environments: Virtual workspaces (SharePoint, Google Workspace) allow remote collaboration but require robust security.

• Digital Footprint: The permanent record of online activity.

  • Active: Data deliberately shared (social posts).

  • Passive: Data collected without awareness (location tracking, cookies).

• Online Communities: Platforms (Reddit, TikTok, Facebook) for shared interests. Monetisation methods include Targeted Ads, Pay-per-click, Selling data, and Paid subscriptions.

• Cloud Computing: Storing data and running applications on remote servers (e.g., Microsoft 365, iCloud).

Topic 4: IT Systems

Systems Design and Analysis

• System Components: Hardware, Software, Processes, and People.

• Decomposition: Breaking a complex system into smaller Sub-systems to analyze them easier.

• Dataflow Diagrams (DFD): Use symbols (circle for process, rectangle for data source/sink, open rectangle for data store) to show how data moves through a system.

• Flowcharts: Visual representation of the sequence of actions and decisions (diamond symbol).

• Evaluation: Checking if a system is Fit for Purpose based on the original requirements in the Design Brief.

Topic 5: Data and Databases

Structuring Data

• Data vs. Information: Data is raw (symbols/values); Information is data with Context. $Data + Context = Information$.

• Structured Data: Fixed format, easily searchable (SQL databases).

• Unstructured Data: No specific format (emails, social media posts); difficult to analyze.

• Data Extraction: Collecting data from sources (Data Mining) to retrieve meaningful patterns for business decisions.

Relational Databases

• Structure: Composed of Tables (Entities), Fields (Columns), and Records (Rows).

• Keys:

  • Primary Key: Unique identifier for a record.

  • Foreign Key: A primary key from one table placed in another to create a link.

  • Composite Key: Using two or more fields together to uniquely identify a record.

• Relationships:

  • One-to-One: One record linked to exactly one other.

  • One-to-Many: One record linked to multiple records.

  • Many-to-Many: Requires a joining entity (middle table) to break into two one-to-many links.

Structured Query Language (SQL)

• SELECT: Choose fields.

• FROM: Identify table.

• WHERE: Filter results (=, <, >, AND, OR, NOT).

• INSERT INTO: Add new record.

• UPDATE: Modify existing record.

• DELETE: Remove record.

• JOIN: Combine data from multiple tables.

• ORDER BY: Sort result (ASC/DESC).

• Wildcards: \% (any number of characters), _ (one character).

Topic 6: Wider Issues

Environmental Impact

• Negative: Resource consumption (precious metals: gold, silver), pollution from manufacturing, and e-waste (toxic techno trash) in landfills.

• Positive: Monitoring dangerous environments, Smart Homes (energy efficiency), and Smart Cities (efficient transport/reduced emissions).

Legal, Moral, and Ethical Issues

• Legality: Data protection laws, Copyright (protecting intellectual property like Berne Convention), and Computer Misuse laws (hacking prevention).

• Ethics/Morals:

  • Privacy: Tracking location without consent.

  • Digital Divide: The gap between those with technology/bandwidth and those without.

  • Accessibility: Features like screen readers, high contrast, and screen magnifiers to help users with disabilities.

  • Bias: Human bias programmed into Artificial Intelligence (AI).