GCSE · Computer Science · Edexcel · Spec 1CP2

Embedded systems

Your laptop will do almost anything you ask. Your microwave does one job, over and over, and never asks. Both are computers — so what's the difference?

Sort it yourself

Embedded or general purpose?

Before you sort anything, ask one question: who chooses the task? You, picking from lots of different tasks — or the designer, once, when the device was built? Pick a device, then pick its category.

Still to sort

Embedded system (0)

A small computer built into a device to control specific functions. Its task, or set of tasks, is fixed.

Where the line is: Plenty of buttons and settings doesn't make a device general purpose. If every setting serves the same one job, it's still embedded.

General purpose computer system (0)

Designed to do many different tasks. The user chooses the task.

Where the line is: Being small doesn't make a device embedded. If you can run lots of applications and switch between them, it's general purpose, whatever its size.

7 of 7 still to sort.

Side by side

Embedded systemvsGeneral purpose computer system

Start with the top row. Every other difference grows out of it.

Focus

Purpose

Embedded system

One task, or a few specific tasks, fixed by its design

General purpose computer system

Many different tasks, and the user chooses which

The insight

This is the big one. It's the same question as the sort: who chooses the task?

Running applications

Embedded system

Does its own job, not a menu of apps

General purpose computer system

Runs multiple applications and switches between them

User interface

Embedded system

Limited, or none at all — it often works without a user

General purpose computer system

A user interface for selecting tasks or applications

Resources

Embedded system

Limited — only what its set job needs

General purpose computer system

More advanced software and hardware

Cost

Embedded system

Lower, because it's designed for a set purpose

General purpose computer system

Higher, because it needs more advanced software and hardware

Computer Science · Structure

One washing machine, several embedded systems

Embedded systems are usually part of a larger system. Tap each one to see its job.

Tap any part of the diagram to see what it does.

What do you really think?

What is an embedded system, exactly?

Your friend is revising and says: "An embedded system is basically a computer inside a computer."

Which idea is closest to what you think right now?

Your friend's right: it's a smaller computer tucked inside a bigger one, like a chip inside a laptop.It's any computer small enough to carry around with you.It's a small computer built into a device to control specific functions. Its job is fixed.It's a computer with no screen and no buttons. If you can press anything, it isn't embedded.

How sure are you?

I'm sureI think soI'm guessing

Your friend's right: it's a smaller computer tucked inside a bigger one, like a chip inside a laptop.

This is a common misconception

This is the most common mix-up, and it's easy to see why after the washing machine: 'part of a larger system' sounds like 'inside another computer'. But the larger system is a device — a washing machine, a microwave, a set of traffic lights. An embedded system is a small computer built into that device to control its specific functions. It isn't nested inside a general purpose computer.

It's any computer small enough to carry around with you.

This is a common misconception

Embedded systems are usually small, but small isn't what makes them embedded. A smartphone fits in your pocket and it's general purpose, because you choose its tasks and switch between its applications.

It's a small computer built into a device to control specific functions. Its job is fixed.

This matches the evidence

Spot on. It's built into a device, it controls specific functions, and it has a specific task or set of tasks to complete. That fixed job is what everything else follows from: the limited interface, the limited resources and the lower cost.

It's a computer with no screen and no buttons. If you can press anything, it isn't embedded.

This is a common misconception

Close, but too strict. Embedded systems have a limited user interface, or none at all. A few buttons, or a small set of options, is still a limited interface. The test is whether the job is fixed, not whether there's anything to press.

An embedded system is defined by its dedicated job: a small computer built into a device to control specific functions. Not by its size, and not by whether it has buttons.

Your turn to write

Explain it in your own words

A smart thermostat adjusts the temperature of a home, using the user's settings and readings from its sensors. Explain why a smart thermostat is an embedded system, and why it is useful to build it this way. [4 marks]

Your answer

0 words · your answer stays on this page and is not sent anywhere.

The mark scheme

It is dedicated to one set task: adjusting (controlling) the home's temperature. (1 mark)
The user can change its settings, but cannot choose it to do different tasks or run other applications. (1 mark)
Dedicating it to a set task reduces its cost. (1 mark)
Dedicating it to a set task reduces its complexity. (1 mark)
It automates heating or cooling, which reduces energy consumption. (1 mark)

Model answer

A smart thermostat is an embedded system because it is dedicated to one set task: adjusting the temperature of the home. The user can change its settings, but they can't choose it to do a different task or run other applications. Building it for one set task reduces its cost and its complexity. It is also useful because it automates the heating or cooling, which reduces energy consumption.

For 'why is it embedded?', name the one job first. Then say what being dedicated to that job buys you: lower cost and less complexity.

WHAT YOU'VE LEARNED

A quick recap of today's lesson.

Some computers will do whatever you ask. Others do one job, all day, and never ask you anything. Learn to tell them apart.

What you need to know

An embedded system is a small computer built into a device to control specific functions. It has a specific task, or set of tasks, to complete.
A general purpose computer system is designed to perform many different tasks. The user chooses the task, it can run multiple applications and switch between them, and it has a user interface for selecting them. Laptops, tablets and smartphones are examples.
The key differences: an embedded system focuses on one or a few specific tasks, has a limited user interface or none, and costs less because it is designed for a set purpose. A general purpose system has many purposes chosen by the user, a user interface, and a higher cost because it needs more advanced software and hardware.
Embedded systems are specialised. They can only do a limited number of things, but they do them very well. They have limited resources and often work without a user.
Embedded systems are usually part of a larger system, each controlling a set function. A washing machine has more than one, for example to control the water inlet, the temperature and the cycle. Because there is more than one inside a machine, each is small and uses less power.
Examples of embedded systems include microwaves, washing machines, automated robotic arms, traffic lights, fitness trackers, smart thermostats, coffee machines, robot vacuum cleaners, security systems, printers, Bluetooth speakers and game controllers.
Traffic lights, smart thermostats and fitness trackers each use an embedded system because each is dedicated to a set task, and dedicating a system to a set task reduces cost and complexity.

The big picture

An embedded system is a small computer built into a device to control specific functions, and its task is fixed. A general purpose computer system does many different tasks: the user chooses the task, it runs multiple applications and switches between them, and it has a user interface for selecting them. Embedded systems are specialised — a few things done very well — with limited resources, a limited user interface or none, and a lower cost because they are designed for a set purpose. They are usually part of a larger system, so each is small and uses less power. Many settings but one purpose? Still embedded.

Key points

1Embedded system: a small computer built into a device to control specific functions.

2General purpose system: many different tasks, chosen by the user, with a user interface for picking them.

3The test is who chooses the task — not the size of the device, and not how many buttons it has.

4Embedded systems have limited resources and a limited user interface (or none), and cost less because they are designed for a set purpose.

5They are usually part of a larger system, so each is small and uses less power.

6Dedicating a system to a set task reduces cost and complexity.

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Worked example

Problem

A coffee machine lets the user choose between several drinks and cup sizes. Is it an embedded system or a general purpose computer system? Justify your answer.

⚠ Watch out

Writing 'embedded systems are cheaper' and stopping there. The reason is the part that shows you understand: an embedded system is designed for a set purpose, while a general purpose system needs more advanced software and hardware.

🧠

Memory hook

Who picks the job? If it's you, choosing from many, it's general purpose. If the designer picked it once, it's embedded — even a washing machine covered in buttons.

✓

Check yourself

Without looking back, explain why an embedded system usually costs less than a general purpose computer system.

Flashcards

(14)

What is an embedded system?

A small computer built into a device to control specific functions. It has a specific task or set of tasks to complete.

What is a general purpose computer system?

A computer system designed to perform many different tasks. The user chooses the task, it can run multiple applications and switch between them, and it has a user interface for selecting them.

Give three examples of general purpose computer systems.

Laptops, tablets and smartphones.

Name four examples of embedded systems.

Any four of: microwaves, washing machines, automated robotic arms, traffic lights, fitness trackers, smart thermostats, coffee machines, robot vacuum cleaners, security systems, printers, Bluetooth speakers, game controllers.

What is the one question that decides embedded or general purpose?

Who chooses the task? The user, from many different tasks (general purpose) — or the designer, once (embedded).

How do the user interfaces of the two kinds of system differ?

An embedded system has a limited user interface, or none. A general purpose system has a user interface for selecting tasks or applications.

What does it mean to say embedded systems are 'specialised'?

They can only do a limited number of things, but they do them very well.

Do embedded systems need a user to work?

Often not. Many embedded systems function without a user at all.

Why is each embedded system in a washing machine small and low power?

There is more than one inside the machine, each controlling a set function, so each is small and uses less power.

A washing machine has lots of cycles to choose from. Why is it still embedded?

Every cycle has the same purpose — washing clothes on different settings. The user changes how it does its job, not which job it does.

Is an embedded system 'a computer inside a computer'?

No. It is built into a device, such as a microwave or traffic lights, to control that device's specific functions — not nested inside a general purpose computer.

What does the embedded system in a set of traffic lights do?

It controls the timing of the lights, using traffic flow sensors or a set programme, to keep traffic safe and flowing smoothly.

Why is a fitness tracker built as an embedded system?

It collects step count, heart rate and sleep data, and needs to be a compact, low-power system to monitor continuously.

What is the benefit of dedicating a system to one set task?

It reduces cost and complexity.

Tap any card to flip it, or use Study as deck to go through them one at a time. In the full lesson these run as a spaced-repetition deck — you rate each card Hard, Good or Easy and the tricky ones keep coming back until they stick.

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Embedded or general purpose?

One washing machine, several embedded systems

What is an embedded system, exactly?

Explain it in your own words

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