An embedded system is a computer built into a larger product to carry out a dedicated function, rather than a general-purpose machine you load arbitrary programs onto.1
Overview
Most embedded systems are built around a microcontroller or system-on-chip running fixed firmware. They are everywhere — in appliances, cars, medical devices, industrial controllers, and radios — usually invisible to the user. Many have hard real-time constraints, met with interrupts and a real-time operating system, while simpler ones run bare metal.
They read the physical world through sensors and act on it through actuators, closing the loop between measuring and doing. The term shades from “deeply embedded” 8-bit controllers with kilobytes of memory up to Linux-class systems-on-chip, but the common thread is a device dedicated to one purpose rather than a computer you install arbitrary apps onto.
Embedded versus general-purpose
The distinction is specialization, not size:
| Trait | Embedded system | General-purpose computer |
|---|---|---|
| Purpose | One dedicated function | Runs arbitrary programs |
| Software | Fixed firmware | Installable apps + OS |
| Resources | Kilobytes to a few MB | Gigabytes |
| Timing | Often hard real-time | Best-effort |
| Visible? | Usually hidden inside a product | The product itself |
Where it fits
The defining trade-off is specialization: an embedded system does one job extremely well, cheaply, and reliably, at the cost of flexibility. When a device also needs network connectivity it becomes part of the Internet of Things. In radio terms, the small transmitters that fill the airwaves GopherTrunk listens to are embedded systems — far too small to run GopherTrunk itself, which lives on a general-purpose computer with an SDR front end. A low-power capture node feeding IQ upstream is one honest exception: it is an embedded-style appliance built for a single job.
Sources
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Embedded system — Wikipedia, on dedicated-function computers. ↩