Know and understand advantages and disadvantages of the different types of computer including portability and expandability

1. Computer Systems – Hardware, Software and the ICT Syllabus

1.1 What is Hardware?

Hardware comprises the tangible components of a computer system that can be seen and touched. Typical examples are:

• Central Processing Unit (CPU)
• Memory modules (RAM, ROM)
• Motherboard and bus circuitry
• Primary storage (HDD, SSD)
• Power Supply Unit (PSU)
• Input devices – keyboard, mouse, touchpad, scanner, digital camera, stylus
• Output devices – monitor, printer, speakers, projector, haptic controllers
• Peripheral devices – USB flash drives, external hard‑disks, network adapters

1.2 What is Software?

Software is a collection of instructions that tells the hardware what to do. It is divided into two main categories:

• System software – manages hardware resources and provides a platform for other programmes.

  • Operating System (e.g. Windows 11, macOS Ventura, Linux Ubuntu, Android, iOS)
  • Device drivers
  • Utility programmes (antivirus, disk‑defragmenter, backup tools)

• Application software – performs specific tasks for the user.

  • Word processors, spreadsheets, databases
  • Web browsers, multimedia editors, games
  • Specialist ICT applications (school‑management, banking, medical, retail, expert‑systems, pattern‑recognition)

2. Core Components of All Computer Types

2.1 Central Processing Unit (CPU)

The CPU is the “brain” of the computer. It carries out the fetch–decode–execute cycle and coordinates all data movement via the system bus.

• Fetch – the control unit reads the next instruction from RAM.
• Decode – the instruction register interprets the opcode and determines the required operation.
• Execute – the arithmetic‑logic unit (ALU) performs calculations or logical operations; results are stored in registers or written back to memory.

Key concepts for the syllabus:

• CPU registers (program counter, instruction register, accumulator)
• System bus (address, data, control lines)
• Multi‑core processors – multiple cores share the same bus but can execute independent instruction streams, improving performance and energy efficiency.

2.2 Internal Memory – RAM vs. ROM

2.3 Input Devices – Overview, Advantages & Disadvantages

2.4 Output Devices – Overview, Advantages & Disadvantages

2.5 Storage Devices & Media – Magnetic, Optical, Solid‑State and Cloud

Note: Primary storage (RAM, HDD/SSD) holds active data; backup storage (tape, external drives, cloud) protects against loss.

2.6 Operating Systems (OS) – Core Functions

• Manage hardware resources (CPU scheduling, memory allocation, I/O control).
• Provide a user interface (graphical or command‑line).
• Run system software and enable installation of application software.
• Handle file management, security, networking services, and peripheral drivers.

Common examples: Windows 10/11, macOS Ventura, Linux (Ubuntu, Fedora), Android, iOS.

3. Types of Computer Systems – Advantages, Disadvantages, Portability & Expandability

3.1 Supercomputers

Extremely fast machines used for scientific research, weather modelling, cryptography and AI training.

• Advantages

  • Petaflop‑level processing speed.
  • Massive parallelism – thousands of cores work together.
  • Huge memory pools (hundreds of terabytes).

• Disadvantages

  • Very high purchase, energy and cooling costs.
  • Fixed installation in specialised data centres.
  • Limited end‑user expandability – upgrades performed by specialist teams.

3.2 Mainframe Computers

Large, reliable systems for bulk data processing in banks, airlines, governments, etc.

• Advantages

  • High reliability and uptime (often >99.999%).
  • Supports thousands of concurrent users.
  • Modular scalability – processors, memory and storage can be added.
  • Robust security and backup facilities.

• Disadvantages

  • High acquisition and maintenance costs.
  • Requires dedicated space, power and cooling.
  • Not portable.

3.3 Servers

Computers that provide services (web, email, database, file storage) to other devices on a network.

• Advantages

  • Configurable for specific roles (e.g., web server, database server).
  • Designed for 24 / 7 operation and redundancy.
  • High expandability – additional drives, RAM, NICs, virtual machines.

• Disadvantages

  • Usually rack‑mounted; limited physical mobility.
  • Initial setup can be complex (network configuration, security hardening).
  • Significant power consumption.

3.4 Desktop Computers

Standard personal computers used at a fixed location.

• Advantages

  • Relatively low cost compared with larger systems.
  • Easy internal upgrades – CPU, GPU, RAM, storage, expansion cards.
  • Broad software compatibility.

• Disadvantages

  • Not portable – requires a desk, power outlet and external monitor.
  • Performance limited by the form‑factor and cooling capacity.

3.5 Laptop (Notebook) Computers

Portable, all‑in‑one devices with an integrated screen, keyboard, battery and internal components.

• Advantages

  • High portability – can be used anywhere with power or battery.
  • All‑in‑one design reduces cable clutter.
  • Built‑in wireless connectivity (Wi‑Fi, Bluetooth).
  • Often include webcam and microphone for online collaboration.

• Disadvantages

  • Limited internal expandability – usually only RAM and SSD upgrades.
  • Smaller keyboard and screen may affect ergonomics.
  • Battery life varies; high‑performance models may drain quickly.

3.6 Tablet Computers

Touch‑screen devices primarily operated with fingers or a stylus.

• Advantages

  • Extreme portability – lightweight, often fits in a pocket.
  • Intuitive touch interface; stylus support for drawing and note‑taking.
  • Long battery life for typical usage (8‑12 hours).

• Disadvantages

  • Very limited expandability – no internal RAM or storage upgrades.
  • Lower processing power than most laptops.
  • Peripheral support often requires adapters (USB‑C to HDMI, etc.).

3.7 Emerging & Specialist Devices (AI‑enabled, XR, Wearables)

• AI‑enabled devices – smart speakers, AI‑accelerated laptops, edge‑AI boxes.
• Extended Reality (XR) headsets – VR/AR devices for immersive learning and design.
• Wearables – smartwatches and fitness trackers with limited computing but high portability.

3.8 Comparison of Portability and Expandability

4. Network, Cloud Computing and Emerging Technologies (Syllabus 4.1‑4.2)

4.1 Networking Basics

• LAN (Local Area Network) – connects devices within a building.
• WAN (Wide Area Network) – links multiple LANs over large distances.
• Wi‑Fi (IEEE 802.11) – wireless LAN; security protocols: WEP (obsolete), WPA2, WPA3.
• Bluetooth – short‑range wireless for peripherals.
• Network security basics: firewalls, strong passwords, MAC address filtering, VPNs.

4.2 Cloud Computing & Services

• Infrastructure as a Service (IaaS) – virtual machines, storage (e.g., AWS EC2, Azure VM).
• Platform as a Service (PaaS) – development environments, databases (e.g., Google App Engine).
• Software as a Service (SaaS) – web‑based applications (Google Workspace, Microsoft 365).
• Benefits: scalability, cost‑effective pay‑as‑you‑go, remote collaboration.
• Risks: data‑privacy, dependence on internet connectivity, vendor lock‑in.

4.3 Emerging Technologies (AI, XR, IoT)

• Artificial Intelligence (AI) – machine learning, natural language processing; used in chatbots, recommendation systems.
• Extended Reality (XR) – virtual reality (VR) and augmented reality (AR) for simulations and design.
• Internet of Things (IoT) – sensors and smart devices communicating over networks (e.g., smart classrooms).

5. ICT Applications – Specialist Domains (Syllabus 6)

6. Systems Development Life‑Cycle (SDLC) – Syllabus 7

1. Analysis – Identify user requirements, define problem, produce a specification document.
2. Design

   • Data structures (tables, fields, relationships).
   • Interface design – mock‑ups, wire‑frames, colour schemes.
   • Validation rules (range checks, mandatory fields, data‑type checks).

3. Development (Implementation) – Write code or configure software, create database tables, set up security.
4. Testing

   • Unit testing – individual components.
   • Integration testing – combined modules.
   • System testing – full solution against requirements.
   • Document test plans, expected results and actual outcomes.

5. Implementation Methods

   • Direct (big‑bang) – switch‑over at once.
   • Parallel – old and new systems run together for a period.
   • Pilot – limited rollout to a test group.
   • Phased – modules introduced sequentially.

6. Documentation

   • Technical documentation – architecture, code comments, API specs.
   • User documentation – manuals, help files, tutorials.

7. Evaluation

   • Assess against original specifications (functionality, performance, security).
   • Gather user feedback, calculate ROI, identify future improvements.

7. Safety, e‑Safety and Legal Issues (Syllabus 8‑10)

7.1 Physical Safety

• Ergonomic workstation setup – chair height, monitor eye‑level, keyboard position.
• Electrical safety – avoid overloaded sockets, use surge protectors.
• Handling of storage media – avoid static discharge, proper e‑waste disposal.

7.2 e‑Safety & Data Protection

• Strong passwords, two‑factor authentication, regular password changes.
• Recognising phishing, spam, and social‑engineering attacks.
• Safe browsing – check HTTPS, avoid suspicious downloads.
• Data‑protection principles (GDPR/UK Data Protection Act):

  • Lawful, fair, and transparent processing.
  • Purpose limitation and data minimisation.
  • Accuracy, storage limitation, integrity and confidentiality.

• Backup strategies – 3‑2‑1 rule (three copies, two media types, one off‑site).

7.3 Copyright, Licensing and Intellectual Property

• Copyright protects original literary, artistic, musical, and software works.
• Fair dealing / fair use – limited copying for education, criticism, news reporting.
• Open‑source licences (GPL, MIT) allow modification and redistribution under conditions.
• Consequences of infringement – legal action, reputational damage.

8. File Management, Compression and Data Handling (Syllabus 11‑12)

8.1 File Management

• Creating, renaming, moving, copying and deleting files/folders.
• Using hierarchical folder structures for logical organisation.
• File‑extension awareness – .docx, .xlsx, .pdf, .jpg, .png, .zip, .rar.

8.2 Compression Techniques

8.3 Image Resolution, Colour Depth and Trade‑offs

• Resolution – measured in pixels (e.g., 1920 × 1080). Higher resolution = larger file size.
• Colour depth – bits per pixel (8‑bit = 256 colours, 24‑bit = 16.7 million colours). Greater depth = richer colours but larger files.
• When preparing images for web or documents, balance quality with file size using formats:

  • JPEG – lossy, good for photographs, adjustable quality.
  • PNG – lossless, supports transparency, larger than JPEG.
  • GIF – limited to 256 colours, supports animation.

8.4 Proofing and Validation Checks

• Range checks – ensure numbers fall within permitted limits.
• Type checks – confirm data is the correct format (numeric, date, text).
• Length checks – restrict character count (e.g., passwords).
• Mandatory field checks – require entry before submission.
• Consistency checks – cross‑field validation (e.g., start date before end date).

9. Document Production, Databases, Spreadsheets, Presentations (Syllabus 13‑16)

9.1 Document Production

• Use of styles (heading, normal, caption) for consistent formatting.
• Page layout – margins, columns, headers/footers, page numbers.
• Inserting graphics, tables, captions and cross‑references.
• Proofing tools – spell‑check, grammar, track changes, comments.

9.2 Database Fundamentals

• Tables, fields, records, primary keys, foreign keys.
• Relationships – one‑to‑one, one‑to‑many, many‑to‑many.
• Queries – SELECT, WHERE, JOIN, aggregate functions (SUM, COUNT).
• Forms for data entry; reports for output.

9.3 Spreadsheets

• Cell references – relative, absolute (\$A\$1) and mixed.
• Formulas and functions – SUM, AVERAGE, IF, VLOOKUP, INDEX/MATCH.
• Data visualisation – charts (column, line, pie) and conditional formatting.
• Data validation – drop‑down lists, error alerts.

9.4 Presentation Software

• Slide design – templates, consistent colour scheme, readable fonts.
• Multimedia – inserting images, audio, video, and animation.
• Speaker notes and slide timings for rehearsals.

9.5 Website Authoring – Three‑Layer Model (Syllabus 17‑21)

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