1. GCSE COMPUTER SCIENCE
Computers
1.7 Control, Models and Virtual Machines

2. Examples of Control Systems include:
- Air conditioning and central heating systems
- Security systems and burglar alarms
- Automatic doors
- Manufacturing processes
- Traffic lights and pedestrian crossings
Microcontroller
Sensors
Output Devices
ACTIVITY
Draw this control system diagram in your book.
This diagram show the different parts of a typical control system.

3. Write this definition of a microcontroller in your book.
Microcontrollers
Microcontrollers are small computers usually with a processor, memory and programmable input and output peripherals.
ACTIVITY
Write this definition of a microcontroller in your book.
Arduino
Microcontrollers are often embedded to provide automated control systems such as car engine control systems, robots and games consoles.

4. Write this definition of a sensor in your book.
Sensors
Sensors are input devices that are used to measure physical properties such as temperature, light, pressure, sound and humidity. They send signals to the microprocessor.
ACTIVITY
Write this definition of a sensor in your book.
Data such as pressure, light and temperature is analogue. Computers can only work with digital data.

5. Write this definition of an actuator in your book.
Actuators
An actuator is a type of motor that is used as an output device for a control system. They allow the system to control movement or action.
ACTIVITY
Write this definition of an actuator in your book.
An example is the Thames flood barrier, actuators are used to open and close the barrier gates.

6. Identify the control key terms from the descriptions:
Activity 1
Identify the control key terms from the descriptions:
Model Type
Description
Microcontroller
Small computers usually with a processor, memory and programmable input and output peripherals.
Sensor
Input devices that are used to measure physical properties such as temperature, light, pressure, sound and humidity. They send signals to the microprocessor.
Actuator
Type of motor that is used as an output device for a control system. They allow the system to control movement or action.

7. Computational Models
There are three different computational models used in computer science. You need to be able describe the characteristics of each of these models:
Sequential
Parallel
Multi-Agent

8. Write the definition of a sequential model in your book.
A sequential computational model is one in which instructions are executed one after another.
There may be branches in the program, but the general principle is that each instruction follows on from the previous one.
ACTIVITY
Write the definition of a sequential model in your book.

9. Write the definition of a parallel model in your book.
A parallel computational model is one in which each program instruction is executed simultaneously on multiple processors in order to get the results faster. Using multi-cores in processors is an example of parallel computing. It is by using parallel processing that super computers are getting faster and faster.
ACTIVITY
Write the definition of a parallel model in your book.

10. Multi-Agent
A multi-agent computational model is one in which computer systems co-operate and co-ordinate with other agents to achieve their goals.
ACTIVITY
Write the definition of a multi-agent model in your book.
Swarm robots are examples of multi-agents.

11. Activity 2
Identify the model type from the description: sequential, parallel, multi-agent.
Model Type
Description
Sequential
One in which instructions are executed one after another. There may be branches in the program, but the general principle is that each instruction follows on from the previous one.
Multi-agent
One in which computer systems co-operate and co-ordinate with other agents to achieve their goals. Swarm robots are examples of multi-agents.
Parallel
One in which each program instruction is executed simultaneously on multiple processors in order to get the results faster.

12. Virtual Machines
A virtual machine is a layer of software that allows one computer to simulate another and to run more than one operating system.

13. Activity 3
Use the Internet to help you find the answer to the following question:
Question
Information
Find out more information about Parallels.
Find out more information about VM Ware.
HINT
Use their websites. Find out information such as cost, operating systems, features, uses etc.

14. Guest Operating System
How Do They Work?
The virtual machine acts as if it is a hardware machine, ‘deceiving’ the guest operating system into believing that it is installed on a computer when in fact it is not.
With the continued increase in processor power, reduction in memory cost and increase in storage capacity, most desktop computers are capable of running many operating systems simultaneously.
Guest Operating System
Virtual Machine
Host Operating System
Hardware

15. Activity 4 Answer these questions in your own words: Question Answer
What is a virtual machine?
A virtual machine (VM) is an emulation of a computer system. Virtual machines provide functionality of a physical computer. Their implementations may involve specialised hardware, software, or a combination.
Explain how a virtual machine works.
A virtual machine is usually software that is installed on a computer. It allows a guest OS to be installed within this software. The guest OS then runs inside a window on the host OS, allowing you to use the guest OS at the same time as the host OS.

16. Activity 5
Use the Internet to help you find the answer to the following question:
Question
Answer
What program is used to install Windows a on Mac computer?
BootCamp
What are the steps to installing Windows on a Mac computer using this program?
Hint: Look on the Apple website!
Check System Requirements
Get a Windows disk image or CD/DVD
Open Boot Camp Assistant
Format your Windows partition
Install Windows
Restart your computer

17. Modelling
Software is often used to model aspects of the real world. They can be used to make predictions about how real world systems will respond to different events.
They allow us to try things out without putting people in danger or damaging equipment.
An example is a flight simulator that allows trainee pilots to practice in a controlled environment safely.

18. Activity 6 Answer these questions in your own words: Question Answer
Why is software used to simulate and model aspects of the real world?
Computer models are cheaper to setup than alternative methods that could be used to predict what will happen in a system, eg building a prototype. Other benefits include being able to: make alterations and quickly see the outcomes, repeat tests several times over, learn from "what if?" scenarios and model dangerous situations safely.
Give some examples of software models or simulations.
Supermarket queues
Stresses which will be borne by a new bridge
Traffic flow in a new road system
Grades for a GCSE class

19. Activity 7
Crossword
Create a crossword based on this topic using the online crossword generator linked below. It should have a minimum of 10 questions.
When you have finished, paste your crossword on to a Powerpoint slide and name it 1.7 Control Crossword.
Print out one copy (include your name) and stick it in your book.
puzzle maker criss-cross