8.4 The OR operation

The OR operation (occasionally called the inclusive-OR operation to distinguish it more clearly from the exclusive-OR operation which I shall be introducing shortly) combines binary words bit by bit according to the rules:

  • 0 OR 0 = 0

  • 0 OR 1 = 1

  • 1 OR 0 = 1

  • 1 OR 1 = 1

In other words, the result is 1 when either bit is 1 or when both bits are 1; alternativel
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4.2 Representing text

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.

References

Revell, P. (September, 2004) Miniature computers are adding up to fun [online] http://education.guardian.co.uk/elearning [story[0,10577,1314016,00.html Accessed 16 October 2006] Guardian Newspapers Ltd.

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18.2 Using e-commerce

Many people now have internet connections and this offers many benefits to both businesses and their customers.

From a customer's point of view, e-commerce has a number of advantages. Shopping can be done from home; you can probably find what you need without trudging from one shop to another and waiting in queues. You can also purchase goods 24 hours a day, every day.

From the point of view of a business, e-commerce also offers a number of advantages. There is a potentially wide
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17.2 The checkout terminal

The first computer block represents the checkout terminal. The processes at the checkout (receiving, storing, retrieving, manipulating and sending data to the user), are the same as I described earlier. However, the checkout terminal also sends data via the supermarket's network.


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16.9 Identity in an ICT system

In a supermarket we might see the following data on an item: 5018190009067. On their own, the digits do not mean very much, but these numbers are typical of the type of data input to a computer system. In this instance, they are numbers from a bar code on a jar of coffee. I have described the numbers here as ‘data’ because in themselves they do not really tell us anything.

When the bar code is moved past a bar code reader at a checkout counter, the checkout terminal will display det
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16.2.3 Manipulating data

Once all items have been scanned, the checkout computer manipulates the data to produce the total cost. If you are paying with cash and require change, the checkout operator will enter the amount you have tendered (an example of the computer receiving data from the user) and the computer will calculate any change required.


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6.2 Working with bits

You may have met the term bit, perhaps in connection with computers. The term ‘bit’ is also important in communication systems. It is an abbreviation for ‘binary digit’. A binary digit can have just one of two values: it can be either 1 or 0. Pulses can be represented by 1s and 0s, that is, as bits, and so it is convenient to think of streams of 1s and 0s being conveyed along the communications link.

The rate at which the 1s and 0s are conveyed is known as the data rat
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1 Describing an ICT system

In this unit I shall be introducing you to some ideas about how ICT systems work. Because this unit is about ICT systems, I'll be starting with a discussion about what constitutes a system. I'll go on to introduce some diagrammatic ways of representing ICT systems. Then I'll look at some examples to illustrate how they carry out certain processes, namely conveying, storing and manipulating data. You will also find out about other processes performed by ICT systems.

In this sectio
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3.6 Viewing the data

Reverting to the relational database we constructed in Section 3.3, you might wonder what, from the user's point of view, has been gained by creating separate tables for the students and courses. With Table 1 you could see at a glance who was studying what. In the relational database it was har
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2.1 Modernising government

Before we start to look at e-government itself, I would like you to read some quotations. During the 1980s and 1990s, the potential of ICT systems for government was discussed by many commentators, but in the UK the official argument for e-government was set out in 1999 in the document Modernising Government. This document, however, is not specifically about e-government. Rather, it is about the much broader issue of how government should be modernised. Here is an extract:


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1 1 Getting the best from interaction devices

Once we have chosen an interaction device for a user interface, we need to consider how to use it effectively. We have relatively little control over the appearance or use of input devices, so we concentrate on the design of the feedback provided by output devices. In particular, we concentrate on the following software components that form this feedback.

  • Text. How can we ensure that the text is legible? Which font should we use? How long shou
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5.2.4 Risk treatment

The risk treatment task is again carried out at unit level, in light of polices set out in Stages 1 to 3. The risks treated are those chosen for control at Stage 6.

  • Stage 7: select control objectives and controls For each risk chosen for control at Stage 6, a suitable control (countermeasure) must be selected from those suggested in the Standard or from elsewhere. The risks are treated in order of priority, according to the priority levels as
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11.4 Controlling cookies in Firefox

  • Open your browser.

  • On the top menu bar of the browser choose Tools > Options.

  • Then choose Privacy in the left panel and expand the Cookies heading.

9 Adware and spyware

The previous sections of this topic have been concerned with email, but the Internet provides yet more problems, in the form of adware and spyware on the Web. You may have seen pop-up messages on your browser screen offering services or products. What you may not realise is that if you respond to these messages, extra software may be installed alongside other programs without your knowledge.

Adware

Adware is ‘free’ software that is subsidised by displaying adverts


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The PROMPT checklist

In the table below is a checklist to help you apply the PROMPT criteria, adapted from the Open University Safari. You can use this to help you evaluate a website.

PROMPT Site 1 Site 2 Site 3
Presentation
Is the informatio
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4.2 Index

It is not practical for the search engine to go looking at every page on the Web whenever it receives a search request. Instead, the search engine consults a vast index to the Web. This index is prepared in advance and is stored as a database to make retrieval as efficient as possible. The index of a search site is just like the index of a book – it contains a list of words, each with a reference to the page on which that word was found. The reference to the original page is, of course, a U
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2.1 Introduction

In this section we will cover the following topics:

  • browsing for information on the Web;

  • searching for information on the Web;

  • using search engines;

  • bookmarking websites;

  • finding images on the Web;

  • how to reference sources.

Some of the material in this section has been drawn from Safari, an interactive website provided by the Open University Library.
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Learning outcomes

By the end of this unit you should be able to:

  • use search engines confidently to locate information and images on the Web;

  • critically address resources that you locate on the Web;

  • describe some of the processes underlying search engines.


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6.3 Devices for automatic control

Sensors and actuators were mentioned in the introduction to the article, Networked microsensors and the end of the world as we know it, that you read in Section 1. Sensors are devices that measure some physical property – for example, temperature, electrical re
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