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A1 · Hardware in a Computer System
Spec reference: Section A1 - Hardware and Software Key idea: Understand the types of computer system, their internal components, and the factors that affect hardware choice and performance.
Types of computer system
| Type | Description | Examples |
|---|---|---|
| Multi-functional device | Combines several functions in one device | Smartphones, tablets |
| Personal computer | Single-user system for general-purpose tasks | Desktop PCs, laptops |
| Mobile device | Portable, battery-powered, touch-based | Phones, tablets, smartwatches |
| Server | Provides services and resources to other devices | Web servers, file servers, database servers |
Each type has different requirements for processing power, battery life, portability, and connectivity.
Internal components
CPU (Central Processing Unit)
The CPU processes instructions. Key components:
- Control Unit (CU): Directs operations, fetches and decodes instructions.
- Arithmetic Logic Unit (ALU): Performs calculations and logical comparisons.
- Registers: Small, fast storage locations inside the CPU.
- Cache: Ultra-fast memory built into or close to the CPU, storing frequently used data.
RAM (Random Access Memory)
Volatile memory used to store data and programs currently in use. Faster than storage but loses content when power is removed.
ROM (Read-Only Memory)
Non-volatile memory containing firmware (e.g. the BIOS/UEFI). Cannot be modified during normal operation.
GPU (Graphics Processing Unit)
Handles graphical calculations. Essential for gaming, video editing, and machine learning. Contains thousands of small cores optimised for parallel processing.
Motherboard
The main circuit board connecting all components. Contains the chipset, expansion slots, and connectors for all peripherals.
PSU (Power Supply Unit)
Converts mains electricity into the voltages required by internal components.
Input, output and storage devices
| Category | Examples |
|---|---|
| Input | Keyboard, mouse, microphone, webcam, scanner, touchscreen |
| Output | Monitor, printer, speakers, projector |
| Storage | HDD, SSD, optical drive, USB flash drive, SD card |
Factors affecting hardware choice
| Factor | Explanation |
|---|---|
| User experience | Ease of use, performance, accessibility |
| User needs | What tasks will be performed |
| Compatibility | Will it work with existing hardware and software |
| Cost | Budget constraints |
| Efficiency | Power consumption, performance per watt |
| Implementation | Timescales, testing, migration from old system |
| Productivity | How much will it improve workflow |
| Security | Physical and data security features |
Data storage and recovery systems
RAID (Redundant Array of Independent Disks)
Combines multiple physical drives to improve performance and/or reliability.
| RAID Level | Description | Use case |
|---|---|---|
| RAID 0 | Data striped across drives, no redundancy. Fast reads/writes. | Speed-critical tasks |
| RAID 1 | Data mirrored across two drives. If one fails, the other takes over. | Critical data protection |
| RAID 5 | Data and parity striped across three or more drives. Can recover from one drive failure. | Servers balancing speed and redundancy |
NAS (Network Attached Storage)
A dedicated storage device connected to a network. Any authorised device on the network can access it. Common in homes and small businesses for centralised file storage and backup.
How hardware features affect performance
| Feature | Impact on performance |
|---|---|
| Clock speed (GHz) | Higher clock speed means more instructions per second |
| Number of cores | More cores allow more tasks to run simultaneously |
| RAM capacity | More RAM allows more applications to run at once without slowdown |
| SSD vs HDD | SSDs load data much faster than HDDs due to no moving parts |
| Cache size | Larger cache reduces the number of times the CPU fetches data from slower RAM |
| GPU cores | More GPU cores improve graphics rendering and parallel processing tasks |
Summary
| Term | Meaning |
|---|---|
| CPU | Processes all instructions in a computer system |
| RAM | Volatile memory holding active data and programs |
| RAID | Array of drives for improved speed or redundancy |
| NAS | Network-connected storage accessible by multiple devices |
| Firmware | Permanent software stored on ROM, e.g. BIOS |