Know and understand characteristics of a desktop computer

1. Types and Components of Computer Systems

1.1 Classification of Computer Systems

Computer systems are grouped according to size, purpose and portability. The main categories relevant to the Cambridge IGCSE/AS‑Level ICT syllabus are:

• Supercomputers – extremely powerful machines for large‑scale scientific simulations.
• Mainframes – large, multi‑user systems used by organisations for bulk processing.
• Servers – provide services (e.g., file, print, web) to other computers on a network.
• Desktop computers – personal computers intended to stay in a fixed location (the focus of this section).
• Laptops / Notebooks – portable PCs with integrated components and a battery.
• Tablets & Smartphones – highly portable devices with touch‑screen interfaces and mobile operating systems.
• Embedded systems – specialised computers built into equipment such as washing machines, cars or medical devices.

1.2 Desktop Computer – Definition and Typical Use

A desktop computer is a personal computer designed to remain on a desk or work‑station. It normally consists of separate, replaceable hardware components, giving it greater flexibility, upgrade potential and cost‑effectiveness than most portable devices. Desktops are the most common platform for school labs, office work, graphics, programming and many emerging technologies (AI, AR/VR).

1.3 Core Hardware Components

Note: The syllabus distinguishes internal memory (RAM/ROM) from backing storage (HDD/SSD). RAM is volatile and loses its contents when power is removed, whereas backing storage retains data permanently.

1.4 System Software vs. Application Software

1.5 Operating Systems – GUI and CLI

In most schools the desktop runs Windows 11 Education, which provides a full GUI and also includes PowerShell/Command Prompt for CLI tasks.

1.6 Input & Output Devices – Analogue vs. Digital Data

1.7 Characteristics of Desktop Computers

• Modularity – Individual components can be upgraded or replaced, extending the system’s lifespan.
• Performance – Higher CPU clock speeds, more cores, larger RAM and powerful GPUs compared with most portable devices at the same price.
• Power consumption – Requires a constant mains connection; typically 150 W – 300 W under load.
• Ergonomics – Supports full‑size keyboards, high‑resolution monitors and adjustable seating, reducing strain.
• Cost efficiency – For a given performance level, desktops are cheaper because components are not limited by size or battery life.
• Heat management – Larger chassis allow effective air or liquid cooling, enabling sustained high performance.
• Connectivity – Numerous ports (USB‑C, USB‑A, HDMI, DisplayPort, Ethernet, audio jacks) and expansion slots.
• Portability – Fixed location; not suitable for on‑the‑move work.
• Expandability – Easy to add extra RAM, storage drives, or dedicated cards.

1.8 Comparison with Mobile Computing Devices

1.9 Example Specification Sheet – Mid‑Range School Desktop

1.10 Simple Performance Estimation Model

For a quick relative comparison of CPU capability:

Performance ≈ Clock Speed (GHz) × Number of Cores

Example: a 3.2 GHz quad‑core processor → 3.2 × 4 = 12.8 (arbitrary performance units).

1.11 Emerging Technologies & Their Impact on Desktop Use

• AI‑assisted development tools – Integrated code‑completion (e.g., GitHub Copilot) runs locally on a powerful desktop, speeding up programming lessons.
• Extended Reality (AR/VR) – High‑performance GPUs enable immersive simulations for science and geography curricula.
• Cloud‑enhanced desktops – Hybrid models where local processing is combined with cloud‑based AI services (e.g., Microsoft 365 Copilot).
• Edge computing – Desktops act as local “edge” nodes processing data from IoT sensors before sending summaries to the cloud.

1.12 Safety and Security

1.13 Practical Activities (AO2 & AO3)

1. Design a file‑naming convention (AO2)
   • Choose a subject (e.g., “Biology”).
   • Define a consistent pattern such as BIOL_YearGroup_Topic_Version.ext.
   • Apply the convention to three sample files and explain why it improves organisation.
2. Evaluate two desktop specifications for a given audience (AO3)
   • Audience: Year 10 students needing word processing, web browsing and occasional video editing.
   • Specification A: i3 CPU, 8 GB RAM, integrated graphics.
   • Specification B: i5 CPU, 16 GB RAM, dedicated GTX 1650.
   • Write a short evaluation (≈150 words) weighing performance, cost, upgrade potential and suitability for the audience.

1.14 Quick‑Reference Cheat‑Sheets for Remaining Syllabus Topics

The following one‑page tables summarise the key points for topics not covered in detail above. They can be printed as revision aids.

1.15 Summary

Desktop computers are versatile, high‑performance machines that offer modularity, ergonomic benefits and cost‑effective upgrades. Understanding each hardware component, the distinction between internal memory (RAM/ROM) and backing storage, the roles of system versus application software, and the advantages/disadvantages compared with mobile devices equips learners to evaluate suitability for a wide range of tasks—from routine word processing to AI‑driven or AR/VR applications—while maintaining safety, security and good e‑safety practice. The included practical activities and cheat‑sheets support the Cambridge assessment objectives (AO1‑AO3) and provide a solid foundation for the remaining ICT syllabus topics.