1. Computer Architecture
IGCSE Computer Science (0478)
  • Chapter 6: Automated & Emerging Technologies
  • Data Representation
    • Introduction
    • Why computers use binary (how binary represents data)
    • Number system
      • Introduction
      • Number Conversions
      • Addition of Binary Numbers
      • Logical binary shifts (positive 8-bit integers)
      • Two’s Complement (Signed: Positive and Negative Numbers)
      • Use of the Hexadecimal System
    • Text, Sound and Image
      • Text, Sound and Images
      • File Types
    • Data storage and File compression
      • Measurement of the Size of Computer Memories
      • Lossless and Lossy File Compression
  • Hardware
    • Computer Architecture
      • The CPU & Microprocessors
      • Von Neumann Architecture
      • Fetch-Decode-Execute Cycle (FDE)
      • Characteristics of the CPU
      • CPU Instruction Sets
      • Embedded Systems
    • Input/output devices
      • Input devices
      • Output devices
      • Sensors
    • Data Storage
      • What is Primary Storage?
      • What is Secondary Storage?
      • What is Virtual Memory?
      • What is cloud storage?
    • Network hardware
      • What is a Network Interface Card(NIC)?
      • MAC Addresses & IP Addresses
      • What is a Router?
  1. Computer Architecture

Embedded Systems

Embedded Systems#

Cambridge (CIE) IGCSE Computer Science — Revision Notes#

1. What is an Embedded System?#

An embedded system is a computer system built into a larger device, designed to perform a specific, dedicated function.
It is not a general-purpose computer (like a laptop or desktop).
It runs continuously, usually without user interaction.
It typically has limited resources (memory, processing power).
It is usually controlled by a microprocessor or microcontroller.

Simple Definition:#

A computer system with a dedicated function within a larger mechanical or electrical system.

2. Embedded Systems vs General-Purpose Computers#

FeatureEmbedded SystemGeneral-Purpose Computer
PurposeSingle, specific taskMany different tasks
User InteractionMinimal or noneHigh (keyboard, mouse, screen)
Operating SystemSimple / noneFull OS (Windows, macOS, Linux)
ResourcesLimited (low RAM, storage)Large RAM, storage, GPU
CostUsually cheapMore expensive
ExamplesWashing machine, pacemakerLaptop, desktop, tablet

3. Examples of Embedded Systems#

Embedded systems are found in almost every modern device:

🏠 Household#

Washing machines
Microwave ovens
Digital alarm clocks
Smart TVs
Air conditioning units

🚗 Automotive#

Anti-lock braking systems (ABS)
Engine management systems
Airbag control systems
GPS navigation units

🏥 Medical#

Pacemakers
Insulin pumps
Digital thermometers
MRI/CT scan machines

📱 Consumer Electronics#

Digital cameras
Printers
Routers and modems
ATM machines

🏭 Industrial#

Traffic light controllers
Barcode scanners
Industrial robots
Smart meters

4. Components of an Embedded System#

An embedded system typically contains:
ComponentRole
Microprocessor / MicrocontrollerThe "brain" — executes instructions
ROMStores the fixed program (firmware) permanently
RAMTemporary storage for data during operation
Input sensorsCollect data from the environment (e.g., temperature sensor)
Output actuatorsAct on the environment (e.g., motor, display, alarm)
ClockSynchronises operations and timing

5. How an Embedded System Works#

Embedded systems typically follow a continuous sense → process → act loop:
┌──────────────────────────────────────────┐
│ │
│ INPUT PROCESS OUTPUT │
│ (Sensors) → (Microprocessor) → (Actuators) │
│ ↑ ↓ │
│ ROM RAM │
│ │
└──────────────────────────────────────────┘

Example — Washing Machine:#

1.
Input: User selects programme; sensors detect water level and temperature.
2.
Process: Microcontroller reads the fixed program from ROM and makes decisions.
3.
Output: Controls the motor, water valve, heater, and display.

6. Role of ROM in Embedded Systems#

The program in an embedded system is stored in ROM (Read-Only Memory).
This program is called firmware.
ROM is non-volatile — the program is retained even when power is off.
The program cannot (easily) be changed by the user — it is fixed at manufacture.
Firmware = software permanently programmed into a device's ROM.

7. Characteristics of Embedded Systems#

CharacteristicExplanation
Dedicated functionDesigned to do one job only
Real-time operationMust respond to inputs within strict time limits
ReliabilityMust work correctly every time, often in critical situations
Low power usageOften battery-powered; must be energy efficient
Small sizeMust fit inside the host device
Low costMass-produced, so must be cheap to manufacture

8. Real-Time Processing#

Many embedded systems must operate in real time — meaning they must process inputs and produce outputs within a guaranteed time period.

Examples:#

An airbag system must detect a crash and inflate within milliseconds.
A pacemaker must deliver an electrical pulse at exactly the right moment.
A traffic light controller must change lights on a precise schedule.
Real-time system: A system that guarantees a response within a specified time constraint.

9. Advantages and Disadvantages of Embedded Systems#

✅ Advantages#

Optimised for their specific task — highly efficient.
Low cost due to minimal hardware requirements.
Small and lightweight — easy to fit inside devices.
Reliable and stable — runs the same program repeatedly.
Low power consumption.

❌ Disadvantages#

Cannot be easily reprogrammed or upgraded.
Limited processing power compared to general-purpose computers.
Difficult to diagnose faults — often no display or interface.
Fixed functionality — cannot adapt to new tasks.

10. Worked Scenario — Embedded System in a Burglar Alarm#

StageDetail
InputMotion sensor detects movement; door sensor detects opening
ProcessMicrocontroller checks sensor data against the stored program
OutputTriggers siren, sends alert to owner's phone, flashes lights
StorageProgram stored in ROM; current alarm state stored in RAM

11. Key Vocabulary#

TermDefinition
Embedded SystemA dedicated computer system built into a larger device
MicrocontrollerA small processor with built-in memory/I/O, used in embedded systems
FirmwareSoftware permanently stored in ROM that controls a device
Real-Time SystemA system that must respond to inputs within a guaranteed time
SensorAn input device that detects physical changes (heat, motion, etc.)
ActuatorAn output device that causes a physical action (motor, valve)
Dedicated FunctionDesigned to perform one specific task only

12. Exam Tips ✅#

Always give specific examples of embedded systems — examiners want detail
(e.g., "a pacemaker" not just "a medical device").
Remember the program is stored in ROM, not RAM.
Be able to describe the input → process → output cycle for a given embedded system.
Know why embedded systems use ROM (non-volatile, program must be retained without power).
Questions often ask you to identify whether a system is embedded — check if it has a single, fixed, dedicated purpose.
Real-time processing is a key feature — link it to time-critical applications.
Modified at 2026-04-03 09:48:13
Previous
CPU Instruction Sets
Next
Input devices
Built with