Embedded systems
Embedded Systems
An embedded system is a computer system built into a larger device for a specific, dedicated purpose. Unlike a general-purpose computer (such as a laptop or desktop PC), an embedded system is not designed to run arbitrary programs chosen by the user. It typically runs a single fixed program stored in ROM, controlling the device it is part of. The user interacts with the device's function - not with the computer inside it.
Embedded systems are everywhere: inside washing machines, cars, traffic lights, medical devices, microwave ovens, and digital cameras. The vast majority of computing devices in the world are embedded systems, not general-purpose computers.
An embedded system is hidden inside a device with a fixed purpose; a general-purpose computer runs programs chosen by the user.
Embedded and Non-Embedded Systems
Embedded Systems - Examples
Embedded systems are found in an enormous range of everyday devices. In every case, the computing component is not visible to the user as a computer - it simply makes the device function.
- Washing machine: a microcontroller manages the wash cycle - controlling the motor, heater, water inlet valve, and drum rotation according to the selected programme. The user presses buttons; the embedded system responds to sensors and executes the appropriate sequence.
- Car engine management system: monitors and controls fuel injection, ignition timing, and emissions. Reads data from sensors dozens of times per second and adjusts engine parameters in real time.
- Microwave oven: controls the magnetron, turntable motor, timer, and display based on the user's input. The program is fixed in ROM.
- Digital camera: processes sensor data, manages autofocus, controls the shutter, and encodes images - all through embedded processors running dedicated firmware.
- Traffic light controller: cycles through light sequences according to a fixed timing pattern or in response to sensors detecting vehicle presence.
- Implanted pacemaker: monitors heart rhythm and delivers electrical pulses at precise intervals - a safety-critical embedded system where reliability is paramount.
Non-Embedded (General-Purpose) Systems - Examples
A non-embedded system - or general-purpose computer - is designed to run a wide range of programs as chosen by the user. The user can install new software, switch between applications, and modify the system's behaviour.
- Desktop PC: can run word processors, games, web browsers, video editors, programming tools - any software compatible with its OS. The user controls what runs.
- Laptop computer: same flexibility as a desktop, in a portable form factor.
- Smartphone: while smartphones contain many embedded components (baseband processor, GPS chip), the main application processor runs a general-purpose OS (Android or iOS) on which users install arbitrary apps.
- Server: runs operating systems and server software to host websites, databases, or cloud services. Programs are installed and updated by system administrators.
- Tablet computer: a general-purpose device running a full mobile OS, capable of running many different applications.
How Embedded and Non-Embedded Systems Differ
| Feature | Embedded system | Non-embedded (general-purpose) |
|---|---|---|
| Purpose | Single, fixed, dedicated task | Many tasks, user-defined |
| Program storage | Program fixed in ROM at manufacture | Programs loaded from secondary storage, can be changed |
| User interaction | User interacts with the device's function, not the computer itself | User directly controls and programmes the computer |
| Flexibility | Cannot run arbitrary programs | Can run any compatible software |
| Resources | Minimal RAM, small processor - optimised for one task | Large RAM, powerful CPU - handles varied demands |
| Operating system | Often none, or a minimal real-time OS | Full operating system (Windows, macOS, Linux, iOS, Android) |
Key Takeaways
- An embedded system is a computer built into a device for a single dedicated purpose. Examples: washing machine, microwave, car engine controller, pacemaker.
- A non-embedded (general-purpose) system can run many different programs chosen by the user. Examples: desktop PC, laptop, server.
- Embedded systems run a fixed program stored in ROM; general-purpose computers load programs from secondary storage and can be changed by the user.
- The user of an embedded system interacts with the device's function, not the computer inside - the computing component is hidden and dedicated.