Embedded Systems
Embedded Systems & General Purpose Computers
An embedded system is a computer system built into a larger device to carry out a dedicated function: one particular job, or a small set of related jobs. Its purpose is to control or perform that function as part of the device, not to run many different programs. The controller inside an electronic keyboard, for example, turns key presses into sounds and runs no other software.
A general-purpose computer is different: it can carry out many tasks, and you change what it does by running or installing different software.
How they compare
| Feature | Embedded system | General-purpose computer |
|---|---|---|
| Main job | One function, or a few related tasks | Many different tasks |
| Software | Fixed program; you cannot normally install new software | You install and run different programs |
| Size, power and cost | Typically smaller, lower power, cheaper | Typically larger, uses more power, costs more |
| Processing and memory | Limited to what the task needs | Much more processing power and memory |
| Complexity and reliability | Simple, so reliable in its dedicated role | Complex, so less suitable for one control task |
Why use an embedded system?
A device may use an embedded system rather than a general-purpose computer to keep the product smaller, cheaper, lower power and more reliable. Smaller means it fits inside the product; cheaper means the whole product costs less; lower power means it can run from a battery; simpler hardware and a fixed program mean fewer things can go wrong.
The keyboard's controller shows this. It is built into the keyboard, has a processor and limited memory, and uses dedicated hardware such as its keys as input. Its fixed program is hard for you to change and is usually held in ROM. A general-purpose computer could also generate sound, but it would bring a full operating system the instrument does not need, and its extra cost, size and complexity would make it a poorer fit for one control task; the keyboard's small fixed controller gives a fast, consistent response to every key press.
Practise this
OCR GCSE Computer Science · Embedded Systems