Lesson 1:

Get in gear

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Year 8 – Computing systems

Objectives

Year 8 – Computing systems

In this unit, you will:

Investigate different layers of computing systems:

• From programs and the operating system
• To the physical components that function together as a system to execute these programs
• To the fundamental binary building blocks that these components consist of

Objectives

Lesson 1: Get in gear

In this lesson, you will:

• Learn what the purpose of a computing system really is
• Explore what programs are, and look at specific examples of programs that we often use

Starter activity

What is Antikythera Mechanism?

The Antikythera mechanism is an Ancient Greek hand-powered orrery, described as the oldest example of an analogue computer used to predict astronomical positions and eclipses decades in advance.

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Starter activity

The Antikythera mechanism

It was retrieved in 1900 from a Roman shipwreck off the coast of Antikythera island.

It was constructed some time in the 1st or 2nd century BC.

Starter activity

The Antikythera mechanism

We now know that it was a complex geared mechanism that could predict solar eclipses, as well as the position of the moon and known planets.

There are dozens of documentaries about the Antikythera mechanism, describing the fascinating attempts to understand its function.

Starter activity

The Antikythera mechanism

Think, write, pair, share .

Would you call the Antikythera mechanism a computer?

How is it similar or different to modern computers?

We now know that it was a complex geared mechanism that could predict solar eclipses, as well as the position of the moon and known planets.

Starter activity

Would you call Antikythera mechanism a computer?

This depends on the definition of the computer. Some would define a computer as any other device that receives input, process it and produces output. In this sense the mechanism is a computer

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However, in this unit, we will be using the term ‘computer’ only for general purpose programmable devices. In this sense the mechanism is not a computer; the processing is hardwired and not prescribed by the program.

Activity 1

The Pascaline and the stepped reckoner

Pascal (1642) and Leibniz (1672) designed calculating machines.

Leibniz’s machine was the first to add, subtract, multiply, and divide.

Question .

How are these machines similar or different to modern computers?

Activity 1

Automate the process

“If we wanted to produce a more admirable machine it could be so arranged that it would not be necessary for the human hand

to move the machine from operation to operation: Things could be arranged in the beginning so that everything should be done by the machine itself.”

Question .

What is Leibniz suggesting here?

Extract from Leibniz’s description of the Machina arithmetica

The “more admirable machine” would follow a program .

Activity 1

Babbage’s Analytical Engine

Babbage (1837) conceived of a programmable machine that would perform calculations, as specified

by instructions on punched cards.

Question .

How is this machine similar or different to modern computers?

Activity 1

Automate the process

Activity 1

Automate the process

This will be our definition of a computer.

Activity 2

What makes a computer different...

...than an appliance such as a dishwasher?

The computer is the only appliance that can do more than one thing. Toasters toast. Refrigerators cool. Lamps illuminate.

One appliance, one task.

But the computer can do hundreds of tasks. The computer doesn’t have a specific, well-designed purpose.

I didn’t know you could do that with a computer! – Dan Gutman (1986)

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Activity 2

What makes a computer different...

...than an appliance such as a dishwasher?

The computer is the only appliance that can do more than one thing. Toasters toast. Refrigerators cool. Lamps illuminate.

One appliance, one task.

But the computer can do hundreds of tasks. The computer doesn’t have a specific, well-designed purpose.

Question .

What are your thoughts on this claim? Do you think that’s true?

Activity 2

What makes a computer different?

The purpose of a general-purpose computer is to execute programs that operate on data.

Activity 2

What makes a computer different?

A computer running an astronomy program can transform itself to provide the functionality of Antikythera Mechanism.

Screenshot of Stellarium

Activity 2

What makes a computer different?

The purpose of a general-purpose computer is to execute programs that operate on data.

Example: A computer running a basic calculator program can provide the functionality of the intricate stepped reckoner.

Activity 2

What makes a computer different?

The purpose of a general-purpose computer is to execute programs that operate on data.

Computer running a chess program can provide the functionality of an electronic chess machine.

Activity 2

And beyond

The purpose of a general-purpose computer is to execute programs that operate on data.

Through each program, the computer transforms itself into a machine that performs a specific task.

Activity 3

Your software

You use programs for every task that you perform on your computer.

The word software simply means programs.

The word computer applies to all kinds of general-purpose computing devices.

Activity 3

Your software

Use the worksheet to write down some of the programs you know.

The word software simply means programs.

The word computer applies to all kinds of general-purpose computing devices.

Activity 3

Your software – Answers

Programs to write documents with:

word processors

Programs to visit websites with:

browsers

Programs to manipulate media with:

video editing, image editing, �sound editing programs

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Subtle point: Sometimes you visit websites to perform these tasks, which might mean that parts of the program are executed on remote computers.

Activity 3

Your software – Answers

Question Are videos, images, and sounds programs?

Answer No, they are data.

Programs are required to read that data and play back the videos, or display the images, or reproduce the sounds.

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When asked if something is a program, you could ask yourself:

Does it perform a task?

Does it process data?

Activity 3

Your software – Answers

Question Are operating systems programs?

Answer Yes. The tasks they perform are to supervise and manage many aspects of the system’s operation.

You will learn more about this in future lessons

Activity 4

Executing a program

Execute the instructions on the intelligent piece of paper, to play noughts and crosses against a human opponent.

This will give you an insight into what it means to execute a program and carry out instructions mechanically.

Activity 4

Executing a program

Work in pairs.

Draw the noughts & crosses 3⨉3 grid.

X goes first and is the mechanical player: follow the instructions blindly.

O goes second and is the human player: play as you like and make sure X follows the instructions.

Switch roles after each game.

Plenary

Concept map

data

instructions

program

computing system

execute(s)

comprise(s)

operate(s) on

This incomplete concept map contains some of the lesson ideas.

Fill in the missing labels, which specify the relationships between them.

Plenary

Concept map

data

instructions

program

computing system

executes

operate on

comprises

This incomplete concept map contains some of the lesson ideas.

Fill in the missing labels, which specify the relationships between them.

Summary

In this lesson, you...

Next lesson, you will...

Describe the hardware components used in computing systems and how they work together in order to execute programs

Highlight how all computing systems, regardless of form, are similar in structure (‘architecture’)

Learnt that the purpose of a general-purpose computing system is to execute programs

Explored what programs are, and looked at specific examples of programs that we often use