Hardware – the physical parts of a computer (processor, memory chips, circuit boards, input & output devices, storage media).
Software – the set of instructions that tells the hardware what to do. It is divided into:
Note: brand names (e.g., Microsoft Word, Adobe Premiere) are not scored – only the type of software matters.
| Aspect | Details |
|---|---|
| Characteristic | Executes program instructions by repeatedly performing the fetch‑decode‑execute cycle. |
| Key Parts | Control Unit (directs operations), Arithmetic‑Logic Unit (performs calculations), Registers (very fast internal storage). |
| Uses | Runs the operating system and all application programmes; performs calculations and logical decisions. |
| Advantages | High processing speed; can execute billions of instructions per second (modern CPUs). |
| Disadvantages | Consumes significant power and generates heat; performance limited by clock speed and architecture. |
| Aspect | Details |
|---|---|
| Characteristic | Non‑volatile – data is retained when power is removed. |
| Writeability | Read‑only in normal operation; some types can be rewritten only with special equipment (e.g., EPROM, EEPROM, Flash). |
| Typical Uses | Firmware such as BIOS/UEFI, boot loaders, embedded controller code, permanent device drivers. |
| Advantages | Data is permanent; provides a reliable place for essential system code. |
| Disadvantages | Slower access than RAM; limited capacity; most types cannot be rewritten by the user. |
| Typical Capacity | From a few kilobytes (micro‑controllers) to several megabytes (PC BIOS). |
| Common Types | Mask ROM, PROM, EPROM, EEPROM, Flash ROM. |
| Aspect | Details |
|---|---|
| Characteristic | Volatile – contents are lost when power is switched off. |
| Writeability | Read/write; the CPU can modify data at any time. |
| Typical Uses | Holds the operating system while it runs, active applications, temporary buffers, and cache. |
| Advantages | Very fast access (nanosecond‑scale); allows rapid read/write operations needed for running programmes. |
| Disadvantages | Data is lost on power‑off; more expensive per megabyte than secondary storage. |
| Typical Capacity | From a few gigabytes in low‑end laptops to tens of gigabytes in high‑performance desktops; servers may use hundreds of GB. |
| Main Types | Dynamic RAM (DRAM), Static RAM (SRAM), Synchronous DRAM (SDRAM), DDR‑x (DDR3, DDR4, DDR5) variants. |
| Feature | ROM | RAM |
|---|---|---|
| Volatility | Non‑volatile | Volatile |
| Writeability | Read‑only or limited rewrite (EPROM, EEPROM) | Read/write anytime |
| Primary purpose | Store permanent firmware & boot code | Provide temporary workspace for programmes |
| Speed | Slower access | Fast access (nanoseconds) |
| Typical capacity | KB – MB | GB – TB |
| Examples | BIOS/UEFI, embedded controller firmware | 8 GB DDR4 module, 32 GB DDR5 module |
| Device | Type | Typical Use | Key Characteristic | Advantages | Disadvantages |
|---|---|---|---|---|---|
| Keyboard | Input | Enter text and commands | Low‑cost, tactile feedback | Fast data entry, familiar layout | Limited to text; not suitable for graphics input |
| Mouse / Touchpad | Input | Point, click, drag | Precision control | Accurate cursor movement, supports multiple buttons | Requires a flat surface (mouse) or can be less precise (touchpad) |
| Monitor / Screen | Output | Display graphics & text | Resolution & refresh rate | Immediate visual feedback, supports colour | Consumes power; size limited by desk space |
| Printer | Output | Produce hard‑copy documents | Inkjet vs. laser, colour vs. monochrome | Creates permanent records, useful for presentations | Running cost (ink/toner), slower than screen display |
| Webcam / Microphone | Input | Capture video and audio | Resolution, sampling rate | Enables video conferencing, multimedia creation | Quality varies; may raise privacy concerns |
| Storage Type | Typical Technology | Typical Capacity | Speed (Read/Write) | Durability | Advantages | Disadvantages |
|---|---|---|---|---|---|---|
| Magnetic (HDD) | Spinning platters, magnetic heads | 0.5 TB – 10 TB (desktop) / 0.25 TB – 2 TB (laptop) | ~80‑150 MB/s (varies with RPM) | Mechanical parts → susceptible to shock | High capacity for low cost, long‑standing technology | Slower than SSD, noisy, higher power consumption |
| Solid‑State (SSD / Flash drive) | NAND flash memory, no moving parts | 128 GB – 8 TB | 300‑3500 MB/s (NVMe) / 500‑600 MB/s (SATA) | Resistant to shock, silent operation | Very fast access, lower power use, lighter | More expensive per GB, limited write‑cycles (though high in practice) |
| Optical (CD / DVD / Blu‑ray) | Laser‑etched pits on plastic discs | 700 MB (CD) – 100 GB (BD‑XL) | ~5‑30 MB/s | Read‑only (for most consumer media) → very stable | Good for distribution, archival, low cost per disc | Low capacity, slower, prone to scratches, largely obsolete for everyday use |
All secondary storage is non‑volatile, retaining data when power is removed, but it is slower than RAM and is used for long‑term data keeping.
An operating system is system software that manages hardware resources and provides a platform for application software.
| Function | Characteristic | Uses | Advantages | Disadvantages |
|---|---|---|---|---|
| Memory Management | Allocates and de‑allocates RAM to programmes | Ensures each programme has its own workspace; supports multitasking | Prevents programmes from interfering with each other | Complex algorithms can add overhead |
| Process Scheduling | Decides which programme (process) runs at any moment | Enables multitasking and efficient CPU utilisation | Responsive user experience | Bad scheduling can cause lag or starvation of processes |
| File‑System Control | Organises data on secondary storage (folders, permissions, indexing) | Allows users and programmes to store, retrieve and protect files | Provides a logical, hierarchical view of data | Corruption or poor design can lead to data loss |
| User Interface (UI) | Provides a way for users to interact with the computer (CLI or GUI) | Command‑line for power users; graphical for most learners | GUI is intuitive, reduces learning curve | CLI requires memorisation of commands; GUI consumes more resources |
Common OS families in the IGCSE syllabus
| Type | Key Hardware Components | Portability | Expandability | Typical Use‑Cases | Advantages | Disadvantages |
|---|---|---|---|---|---|---|
| Desktop PC | CPU, 8‑64 GB RAM, HDD/SSD, separate graphics card | Low (stationary) | High – easy to add RAM, storage, expansion cards | Office work, gaming, software development | Powerful, upgradable, good cooling | Bulky, needs external monitor/keyboard |
| Laptop / Notebook | CPU, 4‑32 GB RAM, SSD/HDD, integrated graphics | High (mobile) | Medium – RAM/SSD upgrades often possible, limited slots | Student work, travel, presentations | Portable, all‑in‑one, battery powered | Less powerful than desktops, limited upgrade options |
| Tablet | System‑on‑Chip (CPU + GPU), 2‑8 GB RAM, flash storage | Very high (hand‑held) | Low – components soldered, storage not user‑replaceable | Reading, web browsing, light apps | Touch interface, lightweight, long battery life | Limited multitasking, weaker hardware |
| Smartphone | SoC, 4‑12 GB RAM, flash storage, integrated radios | Very high | Very low – virtually no user‑replaceable parts | Communication, apps, media consumption | Always with you, rich sensor suite | Small screen, constrained processing power |
| All‑in‑One PC | CPU, 8‑32 GB RAM, SSD/HDD, built‑in monitor | Medium | Medium – internal upgrades possible but space limited | Space‑saving office setups, home media centre | Compact, no separate tower | Harder to service than a desktop, limited expansion |
Regardless of form‑factor, every device contains ROM (firmware) and RAM (working memory) – the concepts are universal.
Analogue data is continuous (e.g., the varying voltage from a microphone).
Digital data is discrete, represented by binary numbers (0s and 1s). Computers can only process digital data, so conversion is required.
Analogue signal ──► ADC (Analogue‑to‑Digital Converter) ──► Digital data
│ │
▼ ▼
Processing (CPU, RAM) Storage
│ │
▼ ▼
Digital data ──► DAC (Digital‑to‑Analogue Converter) ──► Analogue output
Answers
EEPROM/Flash – used for BIOS/UEFI updates and firmware in smartphones.
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