Embedded systems

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About embedded systems

An embedded system refers to a basic computer system embedded in to a device to make it to make it work. An embedded system doesn't do anything else. A non-embedded system means a general purpose computer e.g. a laptop.

Embedded systems are generally made up of a system that includes RAM, ROM and a CPU on a single microprocessor. These typically have lower processing power and are therefore cheaper than general purpose computers.

They often have no user interface or a very basic one. Inputs are often made with buttons, dials and switches. Some embedded systems also receive data from connected sensors.



It is often best to pick a simple device to describe an embedded system e.g. a toaster. A toaster needs a basic computer system to interpret the commands given by the user through the dials and buttons on the toaster. Commonly it will need to get a setting for darkness to determine how long to run. It will need to know to run when the lever is pulled down etc.

A system like this does not need an operating system. The commands can be written in assembly code. In general most embedded systems cannot have their code edited once written as it is stored in ROM. However, some devices can connect to the internet and be flashed with new software. An internet connected TV or your router might get an occassional update of their firmware but items like microwaves are never updated. The software in embedded systems is often referred to as firmware.



Embedded system or general purpose computer

You may be asked to justify whether a device is an embedded system or a general purpose computer. The table below summarises the differences.

Factor Embedded system General purpose computer
Functions Limited number of functions Can perform a large number of functions
Power Needs little power, often runs off batteries Higher power requirements
Processing Basic processing needs Different programs will have different levels of processing needs
Software Software is pre-installed and rarely changed if ever New software can be installed to perform different tasks
Cost Cheap Expensive

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