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Introduction

This course introduces the important distinction between our analogue world of colour, sound, taste and touch and the computer's peculiar binary world of digital entities. Concepts of the analogue universe in which we live and the digital world we create are explained. The way in which information, in the form of text, still and moving images, and sound can cross the boundary from the analogue universe into a digital world is explored.

This OpenLearn course provides a sample of Level 1
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4.9 Making it move

To me, there is a wonderful quality of timelessness about Vermeer's picture of the young woman at her harpsichord. It captures a tranquil moment, frozen for eternity. But of course our visual world is not like that at all. It is dynamic, seething with motion. And schoolchildren have known how to create the illusion of movement since time immemorial. Riffling quickly through a little ‘flick book’ under the desk, with each page showing one step in a moving sequence, as in Author(s): The Open University

4.4 Introducing pixels

Let's try a simple example. I'm going to take an image, divide it into discrete parts and then transform the result into numbers. I shall use the simple picture of a church shown in Figure 12(a). The process will be exactly the same, whatever image we use.


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2.6 Representing true/false quantities

Sometimes a quantity that is to be represented in a computer has only two possible values, either true or false. An example of such a true/false quantity in the kitchen scales is the one that represents whether the scales are to weigh in metric or in imperial measure. The value of this true/false quantity is given by the true/false response to the statement ‘the most recent push of the input button made the measuring system metric’.

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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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2.1 Introduction

Study note: You may like to click on the link below to the Numeracy Resource as you study Section 2. It offers additional explanations and extra practice on some of the topics, and you may find this useful.

Click on the 'View document' link below to open the Numeracy Resource.
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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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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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19 Conclusion

In sections 15–18, we examined the components and processes of an ICT system that is used for an everyday activity: shopping. We started by looking at a system map of the 'checkout system' before exploring the processes involved at the checkout. We considered some examples of networks and discussed the processes involved in a networked supermarket ICT system. Finally, we looked briefly at another way in which ICT systems can be used for shopping: e-commerce.


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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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18.1 Introduction

Most supermarkets now have an online ICT system which allows customers to select and purchase goods from the supermarket's website. Goods are then delivered to the customer's home. Buying and selling things using the internet is known as 'electronic commerce', often shortened to e-commerce.

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17.4 The database server

The computer block on the right represents the database server, which is dedicated to managing a database and making the data available to other computers in the network. The database server receives data via the network. It stores, retrieves and manipulates data, for example by retrieving your previous points total and adding to it the number of points you have 'earned' on this visit. This data is also sent back via the network to the checkout computer to show you the total number of points
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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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17.1 Introduction

I'm going to pause here to try to put together some of the ideas we have encountered so far. I deliberately chose the example of a supermarket to illustrate some of the key processes involved in an ICT system. Figure 15 is a modified version of the block diagram for computers in a network (Author(s): The Open University

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 details
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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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16.7 A loyalty card scheme

Supermarkets, and other types of retailer, use loyalty cards to encourage customers to use their particular shops. Points are awarded when a customer spends money in the shop. Supermarkets 'reward' their customers by converting loyalty card points into vouchers. They may also give them discount vouchers for a range of products.

Supermarkets use their loyalty card schemes to collect data about their customers. Data about each customer is held in a large database where each customer is id
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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 are c
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16.2.4 Sending data

As the items are scanned into the checkout computer, information about the price of each item may be shown on a small display so that the customer can see the price. Sometimes there is a beep as each item passes the bar code reader, to tell the checkout operator the item has been identified. Once all the items have been scanned, the total amount is displayed. Once the customer has paid, they are given a printed till receipt which shows all the items purchased, the price of each and total expe
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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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