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3.3 Other disadvantaged groups

Information on other disadvantaged groups, such as older workers or people with disabilities, is even harder to come by. The problems faced by older workers in the labour market have become an increasing cause for concern in recent years. The nature of the disadvantage faced by older workers is, however, much harder to uncover and the evidence is often anecdotal. One trend that has become evident during the past three decades is the difficulty older workers have in obtaining any work and, in
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7.2 Adding 2's complement integers

The leftmost bit at the start of a 2's complement integer (which represents the presence or absence of the weighting −128) is treated in just the same way as all the other bits in the integers. So the rules given at the start of Section 7.1 for adding unsigned integers can be used.

Example 7


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2.2.1 Positive integers: denary numbers

The number system which we all use in everyday life is called the denary representation, or sometimes the decimal representation, of numbers. In this system, the ten digits 0 to 9 are used, either singly or in ordered groups. The important point for you to grasp is that when the digits are used in ordered groups, each digit is understood to have a weighting. For example, consider the denary number 549. Here 5 has the weighting of hundreds, 4 has the weighting of tens and
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1 Representing data in computers: introduction

A computer is designed to do the following things:

  • receive data from the outside world;

  • store that data;

  • manipulate that data, probably creating and storing more data while doing so;

  • present data back to the outside world.

In the next few sections I am going to examine in more detail the data that a computer receives, stores, manipulates and presents. I
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17.3 The network

The network conveys the data on items purchased through to the database server. It also conveys data such as revised prices and special offers from the database server back to the checkout terminal. In both cases this may involve selecting an appropriate route through the network and manipulating, storing or retrieving data.


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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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16.8 Linking data

We now have two sets of data held by the supermarket: the data about its own products and the personal data about customers. Individually, each of these two sets of information has important uses. However, when they are linked, they provide a very powerful tool for the supermarket.

The personal data from a loyalty card scheme can be used to compile targeted mailing lists, because data about your purchases can help build up a profile of how you spend your money. For example, the supermar
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16.6 Pricing and stock control

A supermarket has a large database of information about its goods, such as the name, price, size and quantity held in stock.

If the price of a particular item changes, the relevant data in the supermarket's database can be easily updated. When the bar code for an item is scanned, the checkout computer searches the database for the item and retrieves the new price. Because the checkout computers are networked, they all use the same data on the database server, so it is not necessary to c
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16.4 The network

The term ‘network’ is used to describe some very different interconnected systems. In a home setting, you might have just two computers linked together to share documents and devices (such as a printer and a scanner) and to use the same internet connection. This setup is a network, albeit a small one. At the other end of the scale is a multinational company with a network of computers distributed all over the world.

A network belonging to a single organisation, where the computers a
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2.2 Memory

You should now be beginning to build up a picture of what a computer is: you know it needs input and output devices to communicate with the world outside and a processor to carry out the instructions that are programmed into it. But where are these instructions stored within the computer? The answer is that they are stored within what is called the computer's main memory, along with any data needed to carry them out.

However, the main memory in computers like PCs is much too smal
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8 Online shopping – what it means

Shopping online is already very big business, and is growing rapidly. This suggests that the concerns of consumers discussed earlier are being addressed by the industry. People wouldn't shop online if they didn't trust it. But in a way the most profound impact of online retailing is being experienced in the ‘real’ world. According to the Economist magazine, for example, the Internet is profoundly changing consumer behaviour in the real world.

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2.3.1 A step-by-step approach to selling

First you have to complete the ‘Sell Your Item’ form. This creates your eBay listing and requires decisions from you on a number of issues:

  • Selling Format Are you selling through eBay's standard auction format, or using your own eBay Shop (using ‘Buy It Now’)?

  • Category Into what category or categories does your item fall?

  • Title Should be clear, complete, and descriptive – and should i
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Acknowledgements

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

Grateful acknowledgement is made to the following sources for permission to reproduce material within this unit.

Figures

Figure 6 NanoElectronics Japan

Figure 30 The Cottingley Fairies © Science and Society Picture Library

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4.2.4 CCD light sensor

The CCD light sensor is a transducer that converts light to an electrical signal. CCD stands for ‘charge coupled device’, and physically a CCD light sensor is an integrated circuit with a transparent cover. A photograph of one is shown in Figure 6. Under the cover is a rectangul
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Learning outcomes

By the time you have completed this unit you should:

  • know the meaning of all the terms highlighted in the text;

  • understand the concept of the ‘network society’;

  • have an awareness of how ICTs impact on your everyday life.


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9 Summary

This unit has introduced the main concepts used in this course, has given an overview of software development with an object-oriented approach and has discussed some of the issues that are relevant to developing software that can be reused. Here are the main points addressed in the unit.

  • An iterative and incremental model for the development process is more appropriate to object-oriented development than a traditional sequential waterfall model. Itera
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8.1 Balanced argument

In many instances, we are not just concerned with arguing a particular case or taking a particular point of view, we are interested in looking at all sides of an issue and producing a balanced argument. This can be helpful in drawing conclusions on an issue.

7.3 Drafting essays

As you may remember from Activity 4, the main elements of an essay are:

  • the introduction

  • the main body

  • the conclusion.


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4.1 Writing requirements

Being a successful writer in one area doesn't always make it easy to know what is required in another. Here are some general questions that you can ask to help define the requirements for particular pieces of writing:

  • What will my tutor be expecting? (this is sometimes phrased as ‘think about the audience’)

  • What is the most appropriate format: report or essay? Do I have a choice, or is it stipulated in any guidance notes I've been
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