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7.1 Adding unsigned integers

Study note: You may like to have the Numeracy Resource (attached below) to hand as you study Section 7. It offers extra practice with the manipulations, and you may find this useful.

Please click on the 'View document' link below to read the Reference Manual.

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6 Manipulating data in computers: introduction

Sections 1 to 5 of this unit have shown that in a computer all types of data are represented by binary codes, and that programmers must make sure that the programs they write treat this data appropriately in any particular application: as text if it is intended to be text, as a binary fraction if it is intended to be a binary fraction, and so on.

Programmers must also ensure that the programs manipulate the binary codes in an appropriate way for the particular application. But what sort
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5 Representing data in computers: conclusion

Study note: You will need to refer to the Reference Manual while you are working through this section.

Please click on the 'View document' link below to read the Reference Manual.

2.2.3 Positive integers: converting denary numbers to binary

If computers encode the denary numbers of the everyday world as binary numbers, then clearly there needs to be conversion from denary to binary and vice versa. You have just seen how to convert binary numbers to denary, because I did a couple of examples to show you how binary numbers ‘work’. But how can denary numbers be converted to binary? I'll show you by means of an example.

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12.2 Bytes of data

You will recall from Section 6.2 that a binary digit, or bit, can have one of two values: either a 0 or a 1. In a computer, bits are assembled into groups of eight, and a group of eight bits is known as a byte. The abbreviation used for a byte is B, so 512 bytes would be written as 512 B. Although this course will use ‘b’ for bit and ‘B’ for byte, you should be aware that not everyone makes this clear distinction.

A byte of data can represent many different things in a co
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11.4 Computer software

The electronic components and other equipment that make up your computer system are known as hardware. In order to make the computer do things, such as help you to produce your TMAs, edit photographs or draw diagrams, you also need computer programs, which are called software.


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7 Describing an ICT system: conclusion

We have arrived at a model of a communication system that illustrates the processes needed for communication. We have also looked at the different kinds of communication link that can be used to convey data, and how to express the rates at which they can convey data. In sections 8–14, we shall be looking at a computer system as an example of an ICT system where data manipulation and storage are the most important features.


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3.1 Tables and flat databases

Databases lie at the heart of many e-government systems, and at the heart of many other ICT systems. The local government websites you looked at in Activity 6, for instance, almost certainly used databases a great deal, as do the majority of central government sites. Away from e-government, the websites for Amazon or eBay, for example, use huge databases.

Constructing a database of any complexity requires careful thought about the way information is organised in any particular context.
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2.3 Styles of presentation

One commodity that is dispensed in vast amounts both by central and local government is information, and so this is one of the more obvious candidates for electronic delivery. Online government services are typically approached via a portal site, which is a kind of entry site from which other sites can be reached. The websites of large organisations, such as Microsoft, the BBC and the Open University, are usually portals.

Going into a portal site is a bit like going into a large
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References

Alberts, Christopher and Dorofee, Audrey (2003) Managing Information Security Risks: The OCTAVE Approach, Addision-Wesley.
Grant, Robert M (1998) Contemporary Strategy Analysis (3rd edn), Blackwell.
Itami, H and Roehl, T (1987) Mobilizing Invisible Assets, Harvard University Press.
Moses, Robin (1992) ‘Risk an
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7 The PDCA cycle

In Section 5 you were introduced to the nine-stage ISMS planning process advocated by the Standard. You have also, in Sections 5 and 6, looked in some detail at some of these stages – those comprising the ISMS documentation and asset identification tasks.

However, an ISMS must not only be planned, it must also be implemented, operated, monitored, reviewed, maintained and improved. Part 2 of the Standard provides guidance on these processes, which it suggests should be undertaken follo
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6.2.2 Threats and vulnerabilities

A hacker who threatens your organisation's information assets is taking advantage of vulnerabilities in the media and systems which handle them. Vulnerabilities and threats clearly go hand-in-hand: each threat is directed at a vulnerability.

The relationship between information assets, threats, vulnerabilities and existing defences is illustrated in Author(s): The Open University

2.1 What is information?

Information comprises the meanings and interpretations that people place upon facts, or data. The value of information springs from the ways it is interpreted and applied to make products, to provide services, and so on.

Many modern writers look at organisations in terms of the use they make of information. For instance, one particularly successful model of business is based on the assets that a firm owns. Assets have traditionally meant tangible things like money, property, plan
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4.1.1 Other files

Scan any files you download from the Internet via your web browser or other software before you run them.

Treat files given to you on a floppy disk, CD or memory stick the same way: scan them before you open them.


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4.1 Email attachments

Following some simple rules should help you to minimise the risks from malware. The first rule is:

  • Never ‘double click’ to open a file attached to an email

Instead, what you should do is:

  • Create a folder called ‘Attachments’ (or something similar) in an accessible location within your file structure. Mine is in ‘My Documents’ and is called ‘My Received Files’.


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3.3 Antivirus software

In conjunction with these patches, you should also install antivirus software. This is because patches and updates are not always issued quickly enough to protect your system from new viral attacks. In addition, patches only stop the types of malware that exploit errors in the program code.

Antivirus software is updated as new malware is found, so it can offer a higher level of protection than just relying on manufacturers’ updates. Antivirus software is specifically designed to catch
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Acknowledgements

The content acknowledged below is Proprietary (see terms and conditions) and is used under licence.

All materials included in this unit are derived from content originated at the Open University.


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2.3 Electromagnetic radiation

To help explain the nature of the waves of energy known as electromagnetic radiation, visualise a pond into which a stone has been thrown. If the state of the pond is ‘frozen’ at an instant in time, the height or depth of the water's surface at that moment will vary with distance from the source of the disturbance. If you were to cut a slice through the pond, you would see a wave shape similar to Author(s): The Open University

1.1 Getting an overview

This section starts with an article from a technical journal – the sort that is read by academics and professionals working in a related technical field. It sets the scene for some of the technologies and issues that you will be encountering later in this unit.

We're not going to ask you to read the entire article, but we would like you to get an idea of the article's contents, the kind of points the author is making, and the range of issues that it throws up. With this aim in mind, w
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Learning outcomes

When you have completed your study of this unit, you should be able to:

  • understand and use correctly terms introduced in this unit in relation to communication networks;

  • understand general principles involved in data exchange between ICT devices;

  • work with numbers expressed in scientific notation, and use the Windows calculator to perform calculations on these numbers.


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