Stretch tasks Embedded Systems

Round 1: Quiz Blitz

1. A computer built into a larger device to do one dedicated task The computer is not the product: the washing machine is, and the computer inside just runs it.
2. Washing machine controller; Pacemaker; Traffic light controller Laptops and smartphones run software the user chooses, so they are general purpose.
3. False Its owner installs whatever apps they like, which makes it a general purpose computer.
4. ROM The fixed program sits in non-volatile ROM, so it is there every time the device powers on.
5. It only needs the hardware its one task requires The designer knows exactly what the task needs, so everything else is stripped out.
6. True Hardware matched to one task needs little power, which suits battery devices such as fitness trackers.
7. Can the user install whatever software they like? Embedded systems have CPUs and some have screens, but their software is fixed.
8. real time A real-time system must respond within a guaranteed time limit. Brakes cannot wait.
9. It can only do the task it was built for; Its software can be hard or impossible to update The trade off is flexibility: one task only, and updates may need a new chip.
10. The task is fixed and well tested, so there is less to go wrong Fewer possibilities means fewer things that can fail.
11. It keeps the cost, size and power use down Low power is deliberate: the task does not need more, so extra power would only add cost and heat.
12. True Many have no operating system at all, but some run a small real-time one. Never say they never have one.

Round 2: Quick Fire

1. • It performs one dedicated task
   • It is built into a larger device
   • It uses little power
   • It is small and cheap
   • Its program is fixed, stored in ROM
   • It is very reliable
   Model answer

   It performs one dedicated task, and it is built into a larger device, such as the controller inside a washing machine.

2. • It is general purpose: it runs many different programs
   • The user can install whatever software they like
   Model answer

   A laptop is a general purpose computer: it runs many different programs, and the user can install whatever software they like.

3. • Advantage: cheaper, smaller, lower power or more reliable
   • Disadvantage: it cannot do anything else, or is hard to update
   Model answer

   Advantage: it is cheaper and more reliable, because it only has the hardware the wash cycles need. Disadvantage: it cannot do anything else, and its software is hard to update.

4. • ROM is non-volatile, so the program is kept when the power is off
   • The program never needs to change, and cannot be changed by accident
   Model answer

   ROM is non-volatile, so the program is not lost when the device is switched off and is ready as soon as it is turned on. The program is fixed and never needs to change, and it cannot be changed by accident.

Round 3: Big Think

1. • Embedded: one dedicated task. General purpose: many different tasks
   • Embedded software is fixed in ROM; general purpose lets the user install software
   • Embedded systems use very little power
   • Embedded systems are cheaper
   • Embedded systems are smaller
   • Embedded systems are more reliable
   • Embedded: a few buttons and lights. General purpose: keyboard, screen and more
   • Embedded: no OS or a small real-time one. General purpose: a full operating system
   Model answer

   An embedded system performs one dedicated task, while a general purpose computer runs many different tasks. An embedded system's software is fixed and stored in ROM, whereas a general purpose computer lets the user install whatever software they like. Embedded systems use very little power, are cheaper and smaller, and are more reliable because there is less to go wrong. They often have a limited interface of a few buttons and lights, and either no operating system or a small real time one, while a general purpose computer has a keyboard, a screen and a full operating system such as Windows.

2. • It is small enough to fit inside the body
   • It uses very little power, so the battery lasts for years
   • The task is fixed and well tested, so it is very reliable
   • It can respond in real time to the heartbeat
   • It only needs to carry out one dedicated task
   Model answer

   A pacemaker has one dedicated task, keeping the heart beating steadily, so an embedded system can be designed just for it. It is small enough to fit inside the body, and it uses very little power, so the battery lasts for years. Because the task is fixed and well tested, it is very reliable, which matters when a life depends on it. It can also respond in real time to the heartbeat.

This or That

1. A gaming laptop The dishwasher's computer only runs wash cycles, so its processor is matched exactly to that small job.
2. A tablet A tablet runs whatever apps its user installs. A traffic light controller does one job.
3. Their hardware is matched to one task The designer strips out everything the task does not need, so there is less hardware to power.
4. ROM The fixed programs live in non-volatile ROM, so they survive when the machine is unplugged.
5. Hard, or impossible without a new chip The software is fixed, often in ROM, so changing it may mean replacing the chip.
6. A real-time system Brakes cannot wait, so the system must respond within a guaranteed time limit.
7. Fewer possibilities mean fewer faults If the device can only do one thing, far less can go wrong, so it is more reliable.
8. Yes: it is built for a few dedicated tasks It counts steps and measures heart rate: a small set of dedicated tasks, so it is embedded.

Memory Match

• A 4 Embedded system: A computer built into a device for one task
• B 6 General purpose: Runs many programs the user chooses
• C 5 ROM: Non-volatile memory holding a fixed program
• D 3 Real-time system: Must respond within a guaranteed time
• E 1 Dedicated function: The one job a system is built for
• F 2 Pacemaker: An embedded system inside the body

Sort It

1. Embedded system Uses very little power and is cheap to make in volume Hardware matched to one task keeps power use and cost down.
2. General purpose A smartphone running apps chosen by its owner The owner chooses the apps, so a smartphone is general purpose.
3. Embedded system Its program is fixed and stored in ROM Embedded systems run a fixed program that rarely, if ever, changes.
4. General purpose Has a powerful processor to cope with unpredictable demands A general purpose computer cannot know what its user will run next, so it needs power to spare.
5. General purpose Lets the user install any software they like Being able to install your own software is the test for a general purpose computer.
6. Embedded system A few buttons and lights are its whole user interface Embedded systems need very limited interfaces, such as a microwave's keypad.
7. Embedded system Controls the wash cycles in a washing machine A washing machine controller does one dedicated job inside a larger device.
8. General purpose Has a keyboard, a large screen and expansion slots General purpose computers need a rich interface because users do many different things.
9. General purpose Usually runs a full operating system such as Windows A full operating system is needed to manage many programs chosen by the user.
10. Embedded system The engine management system in a car It does one dedicated job inside a larger product: the car.