RSS Feed for the unit An introduction to data and information

Introduction

Computers are used to find, store, process and share data and information. The World Wide Web is an example of a vast store of information, which can be searched. This material will introduce you to what a web browser is and how to use one. The use of search engines to find information more effectively on the web will also be demonstrated. This unit looks at how data is transformed into information and relates the topics of data and information to the computer. These are fundamental issues in an understanding of the way in which the computer has shaped and changed contemporary life.

Learning Outcomes

After studying this unit you should be able to:

identify some of the instances in daily life where a computer is, or is likely to be, involved;
given a simple scenario, list most of the obvious information or data required by the parties in that scenario, and give some examples of how the information or data might be used;
explain briefly what perceptual data is, and how it is turned into a form that can be used by a person for reasoning or by a computer for processing;
given a figure, identify whether it is a sign and, if so, what it symbolises;
describe, in simple terms, the difference between data and information;
give a simple explanation of why computers are important to people in terms of data and information;
describe what a parameter is and identify the parameters in a particular scenario;
explain in simple terms what a computer program is, and why one is necessary;
explain the role of the computer with respect to the data given to it;
make use of a search engine to find websites corresponding to a topic of your choice, using some of the advanced search features, and be able to state how many computers (at a minimum) are involved in using a search engine and which role each has;
understand what a gateway is and what advantages it offers a user in searching for a topic;
briefly explain how requirements (e.g. considering the environment in which a computer might be used) affect the presentation of information, giving a simple example;
list some of the problems raised by very large databases even when the basic unit of data is very simple;
explain briefly what advantages a computer system can offer a creative artist and what characteristic enables it to do so;
describe briefly the elements of a distributed system that are needed for selling on the web;
describe the role of computers in controlling mechanical devices;
explain the role of sensors and actuators in a computer-controlled application, given a brief description of that application;
identify some simple safety considerations in a computer-controlled application;
identify appropriate information displays in a given situation.

1.1 What this unit is about

1 An introduction to data and information

1.1 What this unit is about

Each venture

Is a new beginning, a raid on the inarticulate …

T. S. Eliot, ‘East Coker’

Some years ago I was playing with my nephew. ‘Guess what’, he said. ‘My gran remembers before there was television!’ He was clearly thinking about the past in terms of ‘before there was television’.

At that time, I was working in computing, and most people couldn't really understand what I did. Computers were mysterious boxes that were hidden away in large, secure buildings in major companies and government organisations. The average person came in contact with them only in the form of stories in the press or printed statements they received from their bank or gas supplier.

All that has changed, as dramatically and as completely as from ‘before television’ to the present day. Today, most people experience computers not as remote machines producing bills or directing space flight (though they still do these things), but in two ways:

as a medium that combines graphics, video, sound and text to impart information and a means of enabling us to shop on the internet, and so on;
as a ubiquitous but hardly noticeable means of controlling everything from toasters to air traffic.

Whether or not you realise it, you are not only surrounded by computers but you have a persona created by the data associated with you. Some of this data you create yourself, consciously. Some is created when you open a bank account, enrol on a course, shop using a loyalty card, and so on. How much of this persona of yours is public, whether the data it contains is correct, and whether it should be held in the public domain are all things you need to be aware of.

Exercise 1

Take a moment to look in your wallet or purse. What kind of persona do you think you present through the cards and documents it holds? Each of these is likely to mean that some organisation holds electronic records about you.

Now read the discussion

Discussion

This is what I found in my wallet:

driving licence;
two credit cards;
a store card;
three library cards for different libraries;
membership cards for the National Trust and RSPB;
loyalty cards for an airline and a car hire firm;
my National Health Service medical card.

Your wallet or purse is likely to contain similar items. The point is that various organisations (the DVLC in Swansea, the credit card companies, a department store, several libraries, as well as the NHS) all hold data about me. Probably they hold my name, age, date of birth, and address in common, but each will also hold data that is different from the others. For example, I have three bank accounts, two with the same bank, and one with another. The two different banks may have very different views of my finances!

My persona consists of all of this data, whether I am aware of it or not. That is what I mean by a persona: a ‘picture’ of you created by various collections of data about you, such as your finances, shopping habits, interests.

You might like to ask yourself at this point how aware you were, before doing the above Exercise, that so much information about you existed in the public domain.

1.2 Aims of the unit

1 An introduction to data and information

1.2 Aims of the unit

This unit will:

use case studies (real-life examples of interesting aspects of the unit which illustrate particular points) that relate the use of computers to finding, storing, processing and disseminating data and information;
describe various instances of computer use to see how computers can work with data to produce information;
introduce you to what a browswer is, and how to use one;
demonstrate how to use a search engine to find information more effectively.

1.3 Summary

1 An introduction to data and information

1.3 Summary

This section briefly discussed the public awareness of computers and how quickly this has developed from a situation where computers hardly impacted on most people to one where they are involved in virtually every facet of modern life. As an illustration, you examined the contents of your wallet to determine how much data about you (your persona) might be kept by a variety of organisations. This sets the scene for developing an understanding of how this affects you as an individual in modern society.

The aims of the unit were then described.

2.1 The individual: an average day

2 Daily life and computers

2.1 The individual: an average day

If I take an average day in my life, I find myself surrounded by computers, most of which are invisible to me. This section looks at where computers are found in the course of everyday life. It aims to:

place computers in the context of the activities we do and the things we handle in our day-to-day lives.

But it does this from two points of view: the individual and the commercial organisation.

A day in my life

I wake to a radio-alarm. It's controlled by a small computer that lets me set the time I want to wake up and the radio programme that will wake me.

I prepare breakfast on a cooker which has a small computer that controls the clock, timer, and other functions such as oven temperature.

I take my dog for a walk. She has a ‘microchip’ (i.e. a very small simple computer) implanted under her skin that will enable her to be traced if she is lost or stolen.

I take my son to his nursery in the car. It has a number of small computers that control the steering, manage the engine, and control the braking system.

My son's nursery has a computer that children as young as two can use. The nursery keeps its records on a computer and it has a website.

At work, I write material such as this unit using a computer, and find information both from the library catalogues and from the World Wide Web (the web) using my computer. I send and receive emails from colleagues down the corridor or across the world.

During my lunch break I stop at the bank. My computer-produced statement has a confusing entry that I want clarified. On the way out I draw cash from another computer (an automated teller machine or ATM).

I phone a friend using my mobile telephone. It's controlled by a small computer, and my network is able to locate my phone and connect my calls through computer-controlled switching systems.

After picking up my son, I drive to the supermarket. Supermarkets are just one form of business that depends on computers to check stock, order items that are running out and add up sales, among other things. These computers also use my loyalty card to record my preferences, and issue me with vouchers that might entice me to Exercise these preferences.

On the way home I pass a police speed camera. If I were exceeding the speed limit, its computer-controlled system would recognise my number plates, identify me as the owner using the DVLC licensing records, and automatically send me a ticket. (Of course, it's not triggered into action as I pass by!)

Later in the evening my partner and I go to visit a friend who's in hospital. Because we aren't too sure where the hospital is, we use an in-car navigation system to help us get there using the best route.

At the very end of the day, I take a shower which uses a small computer to control the temperature and pressure to ensure I'm neither frozen nor scalded if someone else in the house turns a tap on or off.

The one thing I'm fairly certain of is that my bed doesn't (yet) contain a computer.

Exercise 2

Think about your day as I have thought about mine. Note down the places you visit and things you do in the course of the day, and tick those items you think involve a computer of some kind. As you study this unit, you may want to return to this list to check whether you were right about computers being involved.

Now read the discussion

Discussion

Chances are, if you've chosen an ordinary day, you'll do many of the same things I described above. Many, if not most, of these will involve a computer in some form or other. Most modern mechanical devices are now controlled entirely or partially by computers, including buses, trains and aircraft. Even bicycles are sometimes fitted with a computerised speedometer and odometer.

Most activities these days involve exchanging data or finding and using information – tasks that increasingly are being done by computer.

Exercise 3

Imagine wandering around your local supermarket. Mentally observe the behaviour of other shoppers and the staff at the supermarket. Write down the information that these two groups need.

Now read the discussion

Discussion

There is no single answer to this Exercise. I can only give you some examples.

Shoppers want information about a particular product, where it is, what it costs and perhaps nutritional information associated with the product.

The store manager wants different information, such as:

which items are being sold quickly so that shelves can be replenished and stock reordered;
what the daily turnover of the supermarket is so that new staff can be hired when business increases.

The staff who stack the shelves need to know what products to put on shelves, and where the products can be found.

Staff at the check-outs need to know what some products are (e.g. different fruits, or how to distinguish pastry items) in order to enter the correct codes.

Exercise 4

What sort of information would a doctor need in the course of his or her working day?

Now read the discussion

Discussion

Here is my list of the things I believe a doctor needs to know:

personal information about a patient which enables the doctor to visit that patient;
the patient's medical records which show previous treatments, any adverse reactions to treatments, and so on;
information about the external bodies that deal with patients, such as the location of the nearest pathology laboratory, and the name of the consultants at the local hospital who treat particular disorders;
information about the latest policies and procedures of the NHS;
recent research findings relevant to a patient's condition.

The above list shows how daunting information requirements can be. A doctor needs everything from the simple and obvious (the patient's name and address) to the complex and possibly obscure (the latest research findings on a rare disease).

Data and information

So far, I have used two words in connection with computers: data and information. Did you see any differences in the way the two terms have been used? Let me point out one.

Data refers to discrete items, such as the price of an item on the shelf of a supermarket, or the type of product listed on a sign over a supermarket aisle. The word ‘data’ is a plural Latin word but it is generally used as a singular word in English.

In contrast, information involves linking together two or more items of data to provide an item of knowledge. If someone suddenly said to you, ‘50p’, you'd be a bit puzzled. However, being told, ‘The price of a litre of milk is 50p’, would convey information. In other words, information can be thought of as the answer to a question such as: ‘What is the price of this product?’ So the words ‘50p’ said in connection with nothing would mean little, but stated in answer to the above question would convey information or knowledge.

It's true that the distinction I've made here between data and information may seem fuzzy. One person's data could be another's information (as you will see later in this unit). But for now, please work with the simple definitions given above.

2.2 The organisation: loyalty cards

2 Daily life and computers

2.2 The organisation: loyalty cards

Many supermarkets and other firms (such as petrol companies and airlines) use loyalty cards: cards that offer a customer some form of incentive, such as a future discount or gift, to continue buying from that firm. For example, the British supermarket chain Tesco issues such cards. The holder of a loyalty card is regularly sent vouchers which give the holder discounts from their shopping bills and also vouchers which enable them to gain a discount on items that the supermarket wishes to promote.

When applying for a loyalty card you are required to fill in a form which asks for your name and address, and possibly details about your lifestyle, such as what sort of car you drive, your annual salary range, and so on.

Once you have your loyalty card, it will be swiped through a reader whenever you take your purchases to the check-out.

This subsection is concerned with how a supermarket, or any other organisation, uses the data:

taken from the loyalty card application form;
generated when the loyalty card is swiped through the reader at the check-out.

Exercise 5

Can you think of a use for the postcode data that is written on the loyalty card application form of a supermarket chain?

Now read the discussion

Discussion

You might have said that it is used to send special offers to card holders, and that's correct. However, the senior management of the supermarket chain might use postcode data in a much more subtle way. They often open new branches, and your postcode is a valuable piece of data which helps them to anticipate what the effect might be of opening a new branch in a particular area.

When a loyalty card is swiped at the check-out, the data associated with the holder is linked to the set of products which the holder has just bought. This provides further information for the senior management of the supermarket chain. For example, it could be used to detect whether there is any pattern in the buying habits of customers. If, for example, one product is consistently bought with another (e.g. bottled beer with snacks) this could lead the supermarket chain to display the linked items together in the aisles or near to the check-out in the hope of increasing sales.

2.3 Summary

2 Daily life and computers

2.3 Summary

This section showed that computers pervade our daily lives, but that many of them are invisible to us.

It investigated the information requirements of certain individuals, such as shoppers and doctors. You learned that their requirements can range from the simple and obvious to the complex and not so obvious.

You also learned that it is not just individuals who require information: it is also essential to the operation of organisations. The example of loyalty cards was used to demonstrate how the data associated with such cards could be used to derive information that could be put to subtle use.

The section also provided simple definitions of data and information, and noted that these will be developed further in this unit.

3.1 Making sensation make sense

3 Sensing data and turning it into something usable

3.1 Making sensation make sense

In the previous section you learned something about what data is, where it can be found, and how it can be used. But have you ever thought about how we get data in the first place? As human beings, we are so used to reading, writing, speaking and observing that we rarely think about the true origins of the data we commonly use with such ease. I don't intend taking you back to these origins – that would take too long. Rather, I want to describe how human beings ‘get’ data and put it into a useful form.

This section aims to:

provide a more detailed definition of data;
show in simple terms how human beings can turn sensory data into something that can be communicated and reasoned about.

Before computers, it was mainly philosophers who thought about how human sensation (such as sight or hearing) could be turned into an abstract thing like thought (i.e. ideas or reasoning). To do this, most agreed, sensation had somehow to be transformed into an appropriate form. Once it had such a form, it could become the subject of thought, and human beings could reason about it.

Example 1

If you touch a surface, one of the things you will sense is its temperature, i.e. whether it is hot, cold or neither. This is a survival mechanism: if a surface is so hot, or so cold, that it will damage your hand, you need to remove it immediately. But between the extremes of damagingly hot or cold there are all sorts of other sensory experiences: uncomfortably hot, comfortably hot, comfortably warm, neutral, comfortably cool, and uncomfortably cold. Even these categories can be further divided.

If we were only able to react instinctively to our sensations of hot and cold, we wouldn't be able to convey anything about that surface to another person – for instance to warn them that the surface was damagingly hot or cold. So in the course of our evolution, we have developed the means of transforming sensation into a form that can be thought about and communicated. We have developed words like ‘hot’, ‘cold’, ‘warm’, and ‘cool’. Such words allow us to link one sensation (touch) to another (vision) (e.g. ‘as hot as burning coals’) and use them to convey our thoughts to other human beings who share our language.

But humans have also gone further. Languages have been given written form, which enables us to transmit our sensations and thoughts across time and space, so that someone over four centuries ago could write:

as, the icy fang

And churlish chiding of the winter's wind,

Which, when it bites and blows upon my body,

Even till I shrink with cold, I smile …

(Shakespeare, As You Like It)

and convey to us now the feeling of coldness.

Also, because science doesn't deal in words (such as ‘cold’) which are open to different interpretations, we have developed more objective measures of hot and cold, such as the length of a column of mercury in a thermometer. Thermometers can then be used to compare temperatures by dividing the column of mercury into gradations, called degrees Celsius (written °C). (I n some countries temperature is measured in degrees Fahrenheit.) So everyone will agree that a particular surface with a temperature of 112°C is hotter than one of 91°C, even though both may feel unbearably hot.

The remainder of this section looks at the concept of sensation, and how perceptions of sensation (such as feeling something is warm or seeing colour or hearing sounds) can be represented so that a computer can do something with them.

3.2 Human beings, data, signs and symbols

3 Sensing data and turning it into something usable

3.2 Human beings, data, signs and symbols

We live in a sea of sensation: sight, sound, touch, taste, smell and balance (really a sense of our bodies in three-dimensional space). These sensations, and our ability mentally to process, and then react to and communicate them, are vital to our survival. What we perceive with our senses we call the most primitive form of data: perceptual data.

However, as Example 1 showed, human beings don't just react instinctively; they respond reflectively, using thought. In other words, we seek to name, to classify and finally to understand what we perceive. A reaction like withdrawing your hand from something that is painful to touch is instinctive. Physiologically, such a reaction protects us from harm.

Language, one of the defining characteristics of human beings, is a hugely complex system of meaningful sounds which can be combined and repeated. It enables us not only to name and classify our sensations, but also to communicate them and our thoughts about them to others.

About 30,000 years ago human beings began making ‘useless’ objects: items not strictly necessary for survival. They couldn't be used as tools, eaten or used to keep warm. They were the beginnings of art. These ‘art’ objects were often marked with regular scratches, rhythmic lines or dots. No one now knows what these marks meant to the people who made them. Yet we believe that they were signs conveying specific meanings to those who made and used them (anything from counts of days between full moons to reminders of important events in the stories told around the communal fire at night).

A sign (or symbol: we consider these terms to have the same meaning in this unit) can be defined as something that conveys some information by means other than direct representation. Signs represent something other than themselves: they symbolise something. Signs vary: a beeping sound at a light-controlled pedestrian crossing symbolises that it's safe to cross while the beeping continues, an arrow on a traffic sign symbolises the way to go when it's not obvious (In this unit the terms ‘sign’ and ‘symbol’ are considered to have the same meaning). In the well-known painting, the Arnolfini Double Portrait by Jan van Eyck (shown in Figure 1), the inclusion of the dog in the foreground symbolises domestic fidelity, and the convex mirror in the background symbolises the observing eye of God, keeping watch over the couple.

Figure 1 The Arnolfini Double Portrait by Jan van Eyck (1434) portrays the marriage of Giovanni Arnolfini and Giovanna Cenami, and is rich in Christian symbolism (National Gallery)

The painting includes many other objects which are symbolic as well as representational, such as the shoes, the single candle in the candelabra, and the positions of the couple's hands.

Generally, we distinguish signs and symbols from representations by saying that:

they have a meaning apart from their direct representation;
this meaning is understood by a group of people who agree broadly on what that meaning is.

A flag symbolises a nation or other group, and what is pictured on the flag usually symbolises things important to that group: homeland, language, history or myth. The hands of the couple in Figure 1 symbolise a very ancient custom that the groom ‘asks for the hand’ of his future wife, and the bride ‘gives her hand in marriage’.

Coming back to language, words are also signs. The word ‘cow’ symbolises a particular type of ruminant animal from which we get milk, meat, and sometimes muscle power. The word itself is not a cow; neither is it a particular cow (‘Daisy’); it symbolises the animal we think of as a cow.

Figure 2 From a map by Olaus Magnus, Swedish cartographer, 1539

Exercise 6

Would you call the item shown in Figure 2, and which appears on antique maps, a sign in the sense used above? If so, what does it symbolise?

Now read the discussion

Discussion

It is intended to be a sign that symbolises a coniferous forest on the map (you may have said woods, trees or something similar). Note that most maps have a legend which explains the exact meaning of such signs, although they are intended to be easy to interpret.

Signs can be of many types. There are visual signs (such as road signs), audible signs (beeps and tones used as attention-getters or warnings) and tactile signs (such as textured paving stones near a road crossing).

Exercise 7

Can you think of any other examples of tactile signs? What might their uses be?

Now read the discussion

Discussion

You might have thought of braille, which is intended to be read by those with a visual impairment using the tips of the fingers.

Even for sighted users, tactile signs can be useful. Where the user must use sight or hearing for other things (operating complex machinery), or where vision or hearing is not possible (in very dark or very noisy environments), the position, shape, size or texture of a tactile sign can ensure that the user knows what it is without having to look at it. Most cars, for example, use position to differentiate between two otherwise similar controls such as the indicator lever and the windscreen wiper lever.

An alphabet of touch

Louis Braille, the inventor of the braille system, was only a precocious 10-year-old when he entered Valentin Haüy's pioneering school for children with a visual impairment in 1819. Haüy – a specialist in decoding manuscripts before he founded the school – had already invented a form of writing for people with a visual impairment using an embossed alphabet. Though a great step forward, Haüy's system had its drawbacks: it was prone to errors and confusion.

When Braille was 12, Charles Barbier de la Serre, a French army captain, visited the school and described his system of 12 raised dots representing sounds which could be combined to form words. Braille experimented with Barbier's system and, by the time he was 20, he had simplified it so that each letter of the alphabet could be represented by six raised dots arranged in three rows.

The dots are precisely placed in relation to each other for each character and precisely aligned (sloppily written braille is even harder to read than messy handwriting), and the 63 combinations of dots and positions comprise an alphabet, numerals, the main mathematical signs and a music notation.

Braille is interesting because the basic unit of the sign is, simply, the raised dot, whereas most alphabets compose letters using straight lines, dots, curves and compound marks. Thus braille is very simple and purely abstract (that is, it has no remnants of an iconic system, such as representing the quantity zero by an empty circle). An average braille reader can read about 150 words a minute.

The braille system also freed those with a visual impairment to write for themselves (using a variety of hand- and machine-operated tools). Nowadays computers can produce braille text directly.

In summary, a sign or symbol is a way of representing data. For example, the word ‘blue’ is a sign of a particular colour sensation; a seemingly-simple word like ‘cow’ is a sign of a complex thought or idea derived from many sensations; a road sign can represent some condition of the road (e.g. that it narrows ahead) and warn the driver to take care.

SAQ 1

Describe in your own words what is meant by a sign or symbol, and explain how your personal name is an example.

Now read the answer

Answer to SAQ 1

You might have said something like this: a sign is a representation of something, where the representation could be a sound (such as a word) or a drawing or some other more abstract representation. To be a meaningful sign, there must be a group of people who agree on what the sign represents.

My name is a sign in that it is not me, but represents me to myself and to others (e.g. my family, my employers, my community).

3.3 Data and information

3 Sensing data and turning it into something usable

3.3 Data and information

This unit is also about information, which in Subsection 2.1 was distinguished from data. Whereas data is a discrete item like a price or the name of a product such as milk, information links two or more items of data to give knowledge: e.g. the price of milk is 50p.

To give a simple example, if I said to you that I was standing at approximately 1 degree 40 minutes and 20 seconds longitude west (written 1°40′20″W), 55 degrees, 4 minutes and 57 seconds latitude north (55°4′57″N), you probably wouldn't know exactly where it was. You would need to know the meaning of the words ‘latitude’ and ‘longitude’ to understand that I was referring to a location.

Assume that latitude and longitude and the signs symbolising roads, towns, and so on are data. Longitude measures distance east and west of the Greenwich meridian in (angular) degrees, while latitude measures distance north and south of the Equator in degrees. When they are combined together in a map they become information, because they answer questions about location. You'd find, for example, that the latitude and longitude I mentioned above refer to a place called Ewe Hill in Northumbria, England. On the map, the printed words ‘Ewe Hill’ are the sign of what the place is called.

Human beings turn data into information through a process of:

creating signs to represent the data;
agreeing on what the signs symbolise;
linking these signs in a variety of ways to create information;
communicating that information to other people.

The distinction between data and information isn't always very clear. Is a bus timetable data or is it information?

In my view, it's a lot of data from which I can extract (if I know how to read it) information about when I need to be at a particular bus stop to catch an appropriate bus.

However, to the person who created the timetable from lots of data about when certain buses arrive at various points along a route, the timetable is information about the system of bus travel in a particular geographical area.

So whether something is data or information depends partly on the perspective of the user. Data becomes information in users’ minds when it informs them (answers a question, such as how to use a bus to get from A to B at a particular time).

Here is another example.

Example 2

You and I meet on a street corner. You move your right hand towards me with your hand extended but relaxed and open with your palm held perpendicular to the ground. I perceive the movement. That's the data.

I now need to interpret that data. Are you going to hit me? Do I need to dodge or duck? Because you and I may share at least some common culture, I'd interpret this movement as a gesture to shake my hand, and not as a blow about to be struck. I'd be combining my perception of the movement of your right hand towards me in a particular way with other knowledge I have about cultural signs and their symbolism in order to interpret my perceptual data in a way that tells me I need not fear your arm movements. This knowledge (that the gesture is not hostile) is information. Alternatively I could say that I have used information about cultural norms and gestures in our shared cultural experience to decode the sign you have made with your gesture. Either interpretation is valid; indeed, both are valid.

You might consider the implications of you and me not sharing some cultural norm. Many cultures have a gesture that is intended to convey to strangers that one party has no hostile intent toward the other. However, what happens if one party (X) to the exchange doesn't understand the sign intended by the gesture of the other party (Y)? What if there is some additional data or information available (e.g. Y is carrying a weapon)? How then might X react?

You can see from this that information is very important to us as social beings. It is also possible for information to be false, or for a person to have the wrong information, or for information to be ambiguous (subject to multiple interpretations), or for a person to misinterpret information even when it is not ambiguous. One of the themes running through this unit concerns whether or not you can always trust data and information to be true and whether or not data and information which were once true will remain so.

SAQ 2

Consider a recipe for making a cake. It consists of a list of ingredients and instructions for handling those ingredients.

Is a recipe information or data according to the definitions given above?
In what ways might a novice cook find difficulties in interpreting a recipe?

Now read the answer

Answer to SAQ 2

I consider the recipe to be information, because it answers the question: how do I make a cake? For me the list of individual ingredients and the separate instructions are all data.
There might be many difficulties in interpreting the recipe. The cook might assume that the measurements were in grams when they were in ounces. The recipe could list the instructions in an incorrect order. Also, most recipes in cookery books make assumptions about a cook's prior knowledge; e.g. they may assume that the cook knows what the terms ‘sauté’ and ‘rolling boil’ mean.

3.4 What has any of this to do with computers?

3 Sensing data and turning it into something usable

3.4 What has any of this to do with computers?

Human beings invented computers because we have a compelling interest in data. We seek to turn our perceptions of sensations into symbols, and then to store, analyse, process, and turn these symbols into something else: information. Modern computers, with their enormous storage capacity and incredible processing power, are an ideal tool for doing this. They allow us to acquire data, code it in terms of signs, store, retrieve, or combine it with other data. Sophisticated output devices allow us to present the results of all this processing (i.e. information) in ways that were hitherto impossible, too time consuming, or too expensive.

Long before we developed computers, human beings began developing tools to enhance and extend our perceptions, to help us know better what sort of world we lived in. Telescopes extended our sense of vision by compressing distance for us. We can make temperature sensors to determine the temperature of things so hot or so cold (e.g. the temperature of a kiln or liquid nitrogen, respectively) that we cannot possibly sense these directly without severe harm to ourselves.

Likewise, humans have invented many devices to amplify their muscle power. For example, a hydraulic lift can perform hundreds of times the amount of work that a human or an animal can. Automobiles and jet aircraft enable us to move at speeds and cover distances that would be impossible if we had to depend on our own legs, or even those of an animal like a horse.

Example 3

Remote sensing satellites have been examining the earth from space since the 1970s. They do so using not only the spectrum of light visible to our eyes but also infrared and ultraviolet radiation. The pictures built up through their sensing processes are decomposed into symbols which a digital computer can process. These symbols are stored, and then transmitted to an earth station where another computer converts the symbols back into pictures.

If temperature is sensed instead of light, a picture is built up using a technique called false colour, where colours are assigned to values of (in this case) temperature. Commonly, a so-called ‘cold’ dark colour, like black or deep blue, is assigned to areas of relatively low temperature, and a so-called ‘hot’ colour, like orange, to areas of higher temperature, with intermediate temperatures being represented by other colours.

In other examples, remote sensing is sensitive enough to detect disease or pests in crops before they are noticeable from the ground. It has also located upwellings of colder water in the seas and has resulted in the discovery of two hitherto unknown islands in the Arctic.

Figure 3 shows a false-colour image of a huge ice-storm system over eastern Canada.

Figure 3 This false-colour image of the great ice-storm over eastern Canada on 12 January 1998 was recorded by a remote sensing satellite orbiting at 800 km altitude. Vegetation is represented in green. Open water is depicted in black. The yellow lines represent political borders between Canada and the USA, and between the provinces of Quebec and Ontario. Clouds, ice and frost all appear in various tones of white to blue-white. It is therefore possible to obtain an impression of the extent of the area covered by heavy freezing rain concentrated in southern Quebec and eastern Ontario

Computers started as calculating instruments that took as input numbers symbolising things such as distance to a target and the velocity of a missile, and calculated ballistic trajectories to enable artillery troops to fire shells accurately. However, it quickly became obvious that computers could be used for far more than merely ‘number crunching’, because anything that can be symbolised in an appropriate code can be captured in a computer, stored, processed, and then fed back as information.

Using simple devices, computers can mimic our senses and gather data we have no way of dealing with directly. For example, photographs from space probes cannot come back to earth as rolls of film to be developed: they are transmitted back as radio signals which computers can reassemble into pictures. These pictures can be derived from things we cannot see, such as ultraviolet radiation.

The information that computers produce can be used to control devices like mechanical or hydraulic machinery. For example, computers can be ‘put in charge’ of machinery that might be dangerous for humans to operate, or which might move too fast for our nervous systems to control.

Furthermore, computers have vast memories, and they don't object to storing huge collections of data (e.g. all the tax records of individuals and firms in the UK) that are far beyond the capacity (or, indeed, interest) of a single human being. Once such data is stored, we do not need to remember it: rather we can concentrate on remembering what it describes and where it can be found.

SAQ 3

List at least four ways in which computers are important to human activities. You should think of one or two that are not mentioned above.

Now read the answer

Answer to SAQ 3

You should have listed at least four items similar to the following.

Computers can store large amounts of data.
They are not bored by what people might consider to be trivia.
They can be used to control machinery in remote or dangerous situations or where things happen too quickly for human responses.
They are useful for data analysis.
They facilitate the transmission of data across vast distances by, for example, putting a picture into a form that can be transmitted, and then reassembling it into a picture at the receiving end.

The remainder of this unit will provide some further discussion of the points raised so far and provide examples (called case studies) of how people have used computer systems as tools to process data and produce information.

A computer system is the combination of:

the computer (with its processor and storage);
other equipment such as a scanner or printer,
the software programs that make it all work (software programs that are designed to help with some human task are often referred to as applications).

3.5 Summary

3 Sensing data and turning it into something usable

3.5 Summary

This section examined how human beings obtain data in the first place, by turning sensory data into something that can be communicated and reasoned about.

We ‘code’ this data using signs and symbols that are agreed within a community.

The section explored, again, the distinction between data and information, and noted that one person's data could be another's information.

It went on to describe how humans invented computers because we have a compelling interest in data, and the information we can derive from it. Modern computer systems with their incredible capabilities enable us to sense, store, process, transmit and display data in ways that were previously unimaginable.

4.1 Where am I and how do I get to … ?

4 Computers as tools for finding

4.1 Where am I and how do I get to … ?

Computers can be used to find things and the obvious thing they can find is information. The World Wide Web (WWW or just the web) is just one example of a vast store of information which can be searched to find what you want using computers (The web consists of linked data which is accessed via the internet using a browser). But computers can also ‘find’ things in the sense of locating them geographically, either by generating maps that can be used for navigation or by locating something or someone with reference to a map.

This section aims to:

describe how computers can be used in geographical applications (and, in doing so, it discusses maps and shows that maps can have uses beyond mere navigation);
describe and help you learn how to find information.

As you read on, you should try to determine for yourself:

what data is involved;
how it might be acquired;
what the computer is doing to this data;
what information is being presented, and for what purpose.

You may find it useful to take notes as you go along.

In Section 3, I used an example that gave a location (Ewe Hill in Northumbria) in terms of latitude and longitude, which are parameters for indicating specific locations on the face of the earth. (The word parameter comes from mathematics, and in this unit means a property or characteristic – often measurable or quantifiable – of something.) Any point on the earth can be described in terms of latitude and longitude. Indeed, map-makers have used them ever since reasonably accurate means of determining them were developed in the eighteenth century.

Exercise 8

Can you think of four or five quantifiable and measurable parameters that describe you? If you're not certain about this, try looking in your wallet or purse at things like your driving licence or other documents.

Now read the discussion

Discussion

You might have listed things as: your age in years, your height in centimetres, your weight in kilograms, and your birth date. All of these are measurable or quantifiable characteristics of you.

Maps

Many people are fascinated by maps, and most find them useful, though not in all situations. A lone driver, without a map-reading navigator, will find it difficult to use a map. New in-car navigation systems are designed to help such a driver, or one who is without map-reading skills but is able to follow directions.

The remainder of this subsection uses maps to introduce some important terms and concepts. It also examines a navigation system, used both in cars and in hand-held devices, as an example of the application of computer systems to problem solving.

Maps use latitude and longitude to form a two-dimensional grid that covers the curved surface of the earth.

Altitude or depth (based on a notional sea level) can be superimposed on the latitude and longitude grid using lines connecting adjacent points of the same altitude or depth called contour lines. Contour lines give a map-reader (using a two-dimensional map) an idea of the topography of the area covered by the map.

A map showing only latitude, longitude and contour lines might be of great interest to a geographer. But such a map would be almost useless for, say, a rambler or a driver unless other features, such as roads and villages, were also shown on the map. Examples of two types of map are shown in Figure 4.

Figure 4 Two different types of map. Both cover approximately the same area but look very different. They are for a similar purpose (longer distance travel) but serve completely different audiences

My description of a map implies that maps can be made up of separate layers of data. The idea of layering can best be understood if you imagine that each of the following layers is printed on transparent overlays, except the first (the grid) which is printed on opaque paper:

the underlying grid of latitude and longitude;
contour lines showing altitude;
features such as rivers, roads, buildings and boundaries;
the names of towns, roads, hills, rivers and other notable features of the landscape.

Other types of map may have quite different layers. For example, part of a map showing the incidence of cholera is shown in Figure 5. This was produced by Dr John Snow in 1854, and is a classic example of medical cartography. It proved that cholera was a water-borne disease.

Figure 5 A portion of Dr John Snow's map of part of London. The layers in this map consist of: (1) the relevant 1854 London streets, (2) the location of 578 deaths from cholera and (3) the position of 13 water pumps. Each location of a death specifies the address of a person who died from cholera. When many such locations are associated with a single address, they are ‘stacked’ in a line away from the street so that the numbers of deaths at an address are more easily visualised. (Using this mapping technique, Dr Snow identified a contaminated pump as the source of the cholera outbreak. By removing the handle of the pump once he'd identified it, Dr Snow averted an epidemic.)

Early maps were drawn using counted paces, and local knowledge for place and feature names. However, as the need for greater accuracy grew, geographical data began to be gathered by a painstaking and exacting process of measurement carried out by surveyors. The tools used in the task included chains of an exact length, accurate clocks, sextants and theodolites. Modern mapping still uses some of these, but also relies on aerial photography, on remote sensing from orbiting satellites (described in Example 3) and, increasingly, on the global positioning system (GPS) described below.

Geographical data

Modern maps are now mostly assembled by computers using very large collections of geographical data, such as latitude, longitude, altitude, roads and towns. Collections of data like this (stored in databases) aim to eliminate the need to duplicate data. The data in databases is described in symbols that the computer can handle, i.e. numbers. Even the names of features are symbolised using numbers.

If I were trying to tell you the way to a particular street in a town, using only the numbers that a computer uses for geographical data, they would be meaningless to you. Even if you knew the meaning of the individual symbols, there would be too many of them for you to make sense of.

Since maps are constructed from layers of data, it's possible to leave out some layers in order to achieve a particular purpose, or to substitute other layers to achieve a different purpose. For example, features such as roads, buildings and boundaries can be left out in order to produce a map of interest to certain types of geographer; or population figures can be transformed into appropriate symbols to produce a map of interest to, say, an epidemiologist studying the spread of disease.

Map users like hikers, drivers, pilots and sailors need to have a much more understandable version of geographical data. They might use a map printed on a large sheet of paper, such as one of the Ordnance Survey maps of the UK. However, paper maps have their drawbacks. For example, they require a user to learn how to read them, they don't show the user where he or she is, and they need to be unfolded and refolded.

This highlights a very important theme of this unit: fitness-for-purpose. A physical geographer wants certain things from a map (e.g. topographical contour lines) and will probably want to see geographically important features such as soil types. A hydrologist will be more interested in a map that emphasises bodies of water and watersheds. Ramblers want to see footpaths and field boundaries. Drivers want to see roads, junctions and streets in towns.

Global positioning system (GPS)

These days, it is possible to buy a device known as a global positioning system (GPS) to tell you where you are. Receivers are made for aircraft, ships, ground vehicles, and (as the one shown in Figure 6) for carrying in the hand.

Figure 6 The Lowrance iFinder, an example of a hand-held GPS receiver for use by sports people

Examples of applications for GPS are:

navigation;
surveying, and establishing the shortest distance between two points (a line of sight along the ground is no longer necessary for precise positioning, so greater distances, with features such as hills obscuring the line of sight, can be surveyed much more easily);
plate tectonic studies (seeing how large areas of the earth's surface move relative to each other).

The worldwide GPS is funded and controlled by the US Department of Defense (DOD) but its standard positioning service is used by many thousands of civilian users worldwide. More expensive receivers, such as those used in aircraft, are more accurate than the standard service used by most recreational receivers.

The system involves a network of satellites in orbit around the earth, which provide specially coded signals that can be processed in a GPS receiver. Signals from four GPS satellites enable the computer in the receiver to compute the receiver's position in three physical dimensions (i.e. latitude, longitude and altitude), the receiver's velocity, and a highly accurate time. (Velocity is speed plus direction.)

The satellite system for GPS

The GPS satellite system consists of at least 24 satellites in orbit at any one time. The placement of the satellites is such that a user's ground-based receiver can receive signals from between five and eight satellites from any point on the earth's surface. Satellite orbits are calculated and controlled from a series of ground stations, one of which (in Colorado in the US) is the master station.

Most leisure users of GPS receivers want to relate position, and perhaps movement, to particular places and features in the landscape. It may be no use to a hiker (trying to get to the next refuge) to come to the foot of a high cliff believing that she's travelling in the right direction; she needs to know the cliff is in the way of her direct line of travel. This is where the geographical data that goes into making maps comes into its own.

Most GPS systems (other than very simplest) allow users to superimpose their position information onto a map created from a collection of geographical data that can be loaded into the GPS receiver. As the user moves through an area, the map is constantly updated keeping the user at the centre of the map. What transforms the data into a map (information) which can be understood is a small computer contained within the receiver device.

Figure 7 shows a GPS receiver manufactured by the American company Garmin for BMW motorcycles, and gives an example of how the GPS receiver's position is ‘placed’ at the centre of the map.

Figure 7 An example of a GPS receiver storing geographical data for producing maps; the small arrow at the centre of the map indicates the current position and direction of the motorcycle carrying the GPS receiver

What happens when a map is wholly inappropriate, e.g. when navigating in the dark, smoke or fog, or if the user has a visual impairment? In such situations oral directions are needed. These use words like left, right, straight ahead, crossroads, junction, and so on to describe both surroundings and the ‘features’ of a journey. While rare, it is possible for something like a GPS receiver to be programmed to give audible directions as an alternative (or supplement) to a map: ‘Proceed straight ahead for 100 metres before turning left 90 degrees into Porchester Road …’.

Such devices are being further developed as hand-held aids for:

those with a visual impairment to navigate campuses, shopping malls and buildings;
members of the emergency services who may have to find their way around an unfamiliar building quickly in thick smoke and darkness.

Since, in the case of buildings, GPS signals don't work to a small enough scale and don't penetrate into such structures, they can be supplemented by small local signal beacons or even bar codes on doors and in corridors.

Even without a GPS receiver, you may still benefit from the way computers can represent geographical data. Motoring organisations offer a free route-planning service over the web that gives directions from one place to another. This works out a route on which it's possible to apply constraints, such as taking the fastest route or taking the shortest route or avoiding road works. I typed in my location and a friend's, and received a printable map with the route highlighted (not shown) and a set of directions shown in Figure 8. Even if I couldn't read a map, I could use these directions.

Figure 8 A route between Biddenham and Leagrave in Bedfordshire, obtained from a route-planning service on the web. Taken from www.theaa.com. AA recommended.

There are three important themes in this case study on maps that will recur throughout this unit.

The right sort of data, properly used, is a very powerful aid in creating appropriate information (e.g. generating maps from geographical data).
It is possible to present information in a variety of ways to meet different requirements (e.g. a map for a hiker or directions for those who find maps daunting).
A computer can transform data into information in ways not previously thought possible (e.g. the information on a GPS receiver).

Here are some further examples of how a computer system can use the right sort of data to generate useful information in an appropriate way.

A computer in a microwave oven transforms the pulses of an electronic clock into a time display that shows how long until the cooking is finished.
A computer in a satellite television control box obtains the signals emitted by a transmitter satellite and converts them into a television picture and sound for the attached television set.
The computers in a nuclear power station monitor signals produced by pressure sensors and other devices to provide a moment-by-moment summary of the state of the reactor.
A computer in a car turns the pressure of the driver's foot on the brake pedal into fine control movements of each wheel's brake so as to prevent the car from skidding.
A powerful PC turns signals from a scanner into a representation on the computer's screen of the item scanned. The PC can then accept commands from the user to modify that image.

It is transformations like these that lie at the heart of this unit.

Exercise 9

Consider a computer in a modern cooker.

What kinds of data might it require and where would these originate?
What kinds of information might it present to the cook?

Now read the discussion

Discussion

The data originates either from the cook (pressing buttons to set a timer, for example) or from signals from the cooker's clock or its temperature sensor inside the oven.
A small display might show the time on the clock, how much time is left on the timer, and the oven temperature.

SAQ 4

What is the role of the computer with respect to the data given to it?
How should requirements (such as the need for a user's attention to be focused on a complex task like driving) affect the presentation of information?
What, in your own words, is the meaning of the term parameter?

Now read the answer

Answer to SAQ 4

The role of the computer is to transform data into information.
The presentation of information needs to be fit-for-purpose and, in the example given, presented in a way that lets the user keep their primary focus of attention on the task.
A parameter is a property or characteristic of something that is measurable or quantifiable.

4.2 Finding information: the web

4 Computers as tools for finding

4.2 Finding information: the web

The web is a vast storehouse of ever changing, linked information on subjects as diverse as dog breeding, astronomy, tiddlywinks, and coping with bereavement.

A browser, like Internet Explorer, is used to access the web. However, given that the web contains literally billions of words of text, how would you find information on, say, the Open University?

The internet and the web: what's the difference?

People sometimes confuse the internet and the World Wide Web.

The internet refers to the physical interconnection of large numbers of smaller data communications networks to form a huge, publicly accessible ‘network of networks’. Thus the internet carries electronic mail (email), hosts chat rooms and bulletin boards, enables the transfer of files, and is the physical basis for supporting the World Wide Web.

The web is the collection of linked data stored on the internet which is accessed using a browser.

Search engines: what are they?

The computer application that facilitates finding things on the web is known as a search engine. This is an application that serves a similar function to an index in a book. Figure 9(a) shows the home page of a typical search engine called Google.

Figure 9(a) The interface to the Google search engine

There is a single box shown in Figure 9(a) into which keywords (words or terms that identify and distinguish topics from other topics) are typed. The keywords used in Figure 9(a) are ‘rugby’ and ‘wales’.

The use of ‘Rugby’ and ‘Wales’ would produce the same results.

When the button labelled ‘Google Search’ is clicked (or the ‘Return’ key is pressed), the search engine finds and returns a list of references to any websites which match all the keywords. Figure 9(b) shows the results of search for 'Rugby Wales'. In this case there are more results than will fit on a single screen, and only the first screenful of results is shown.

Figure 9(b) The output from the Google search engine in response to the keywords ‘Rugby’ and ‘Wales’

There are a number of references to the game of rugby in Wales, with the first being to the Welsh Rugby Union's home page. Each of the entries in blue (and also those underlined) can be clicked on to see more detailed information.

Ego surfing

The web is full of its own special jargon, abbreviations and acronyms. An example is the term surfing, which refers to the process of wandering around the web searching for information. The term ego surfing describes the act of looking for information about oneself.

Yahoo and Lycos are also web search engines. Like Google, they find results based on keywords, although you may find that each gives slightly different results to the same search. Figure 10 shows two displays, one from Google and one from Lycos, using the same keywords: ‘maps in history’.

Different search engines give different results owing to the way in which they classify websites, and the relative importance they give to different features.

As the web changes constantly, repeating a search a few days later may well produce slightly different results. It is instructive to understand the steps involved when a web search engine is used; assume you have run your browser, invoked a search engine and chosen the keywords you are interested in. You will learn how to invoke a search engine in activity 1.

It is instructive to understand the steps involved when a web search engine is used; assume you have run your browser, invoked a search engine and chosen the keywords you are interested in.

The keywords are transmitted over the internet to a special computer known as a web server. This web server contains an index to websites. Each website is associated with a series of keywords which can be found in the site's title, address or contents. The index keywords and the user's requested keywords are compared by the server.
The web server then retrieves references to those websites that contain the right keywords and sends details of each reference back to the user's browser.
The browser then displays the references for the user.

Here data (the keywords) is used to assemble information (the references to websites) but I have introduced some additional ideas here.

Computers can communicate with each other, and two or more computers can cooperate to provide a service to users.
Some remote computer, the web server, contains data that the user, who could be anywhere in the world, wants to access. This web server computer holds the index used to select those websites relevant to a user's search.
Possibly the most important idea is concerned with the sentence in step 2, 'The web server then retrieves references to those websites that contain the right keywords …'. The computer certainly does this, but how? The answer is that a computer program stored inside a computer carries out the actions necessary to do whatever it is that the computer system is designed for (in this case, to search through an index of websites seeking keywords that match the user's request).

Figure 10 Different search engines, same search (on ‘maps in history’), different results! Note that the first, second and third entries on each display point to the same websites, but with different descriptions

A computer program is essentially a step-by-step set of instructions that tell the computer what to do. In other words, it's analogous to a cookery recipe. Computer programs are often referred to as software programs or simply programs. Notice the spelling of the word 'program'.

Translated into English the instructions in a computer program (all written in specially designed language) might read as follows:

extract the keywords from the user's search engine web page;
send the keywords to the web server.

This would happen on the user's computer (often referred to in this context as a client). On the web server, the instructions might be:

extract each keyword from the message sent by the user's browser over the internet;
search the index for all websites that contain all the keywords.

Computer programs can be as small as a few instructions or contain hundreds of thousands of instructions.

Using the web more effectively: gateways

A gateway on the web is a website intended to direct users to other preselected websites containing information on a particular topic. It can also refer to a computer that acts as a message router on the internet

University librarians often set up gateways for particular areas of study, although they may be set up by anyone with sufficient expertise in a topic. Gateways may be fairly general, such as a gateway site for sciences, or more specific, such as a gateway for particle physics.

Professional or vocational bodies may also develop gateways useful to their members, as may hobby organisations. A well-known gateway for people interested in family history and genealogy is Cyndi's List. This is updated by volunteers who notify new links relevant to topics of interest such as seventeenth and eighteenth century ships' passenger lists, local history websites, lists of names of war veterans, and so on.

Many gateway sites are searchable, often using the same search engines (e.g. Google) that are available directly through browsers. Because the search engine limits its search to the gateway site's indexes, this can prove to be a more focused way to search, particularly if the topic is one that is likely, in the wider web, to yield lots of spurious results.

Figure 11 shows the main page of a gateway website about historical maps and cartography aimed at academics, students, historians and map collectors. It contains the following:

a selectable list of main topics on the left, each of which may contain links to other pages or other websites;
selectable boxes at the top giving the index to the site, a site map page explaining how the site is organised, an ‘ABOUT’ link telling the user who hosts the site (the Institute of Historical Research at the University of London), and a ‘WHAT'S NEW’ link with information about recent changes to the site;
welcoming messages (stating who the intended audience of the site is);
a search engine with which to search the site.

Figure 11 The main page of the gateway website for map history and the history of cartography

Using a search engine more effectively

The search shown in Figure 9(b) is an example of how to use a search engine in a simple way. However, one of the problems with finding information on the web is that there is so much! And not all of it is relevant to what you want. My search for ‘rugby’ and ‘wales’ using the Google search engine yielded about 420,000 results or ‘hits’ (see the information contained in the blue strip on Figure 9(b)). The first few sites listed will probably tell me what I want to know. But what about all the others? Are they all about the game of rugby in Wales?

The answer is ‘no’. A website about rugby in New South Wales, Australia also appeared as a result of this search. Google didn't make a mistake since the site contains the chosen keywords. However, it wasn't smart enough to distinguish between Wales and New South Wales.

If you are just looking (‘surfing’) for information in a general way, too much information isn't always a problem. Where it becomes irritating and counterproductive is when you are looking for some quite specific information.

Example 4

Suppose you're interested in genealogy, and your surname is Bird. If you search on the web by typing in the keywords ‘bird’ and ‘family’, the web server will return every website it finds with those two words in it, so you'll probably find scientific and hobby sites on bird ‘families’ such as the passerines! It's clearly not what you want, but do you need to examine all the websites returned (which could run into hundreds) to find the one you're looking for?

The answer is that there are ‘tricks’ that you can use to narrow down your search to eliminate at least some of the things you aren't looking for. Each search engine has its own ‘tricks’, though the concepts of making more targeted searches are common to most search engines. Search engine screens will generally have a selectable topic called something like ‘Advanced Search’ or ‘Search Tips’.

One obvious trick is to choose your keywords carefully. The more specific the keywords you choose, the more likely you are to get what you want. For example, if you want to find information on antique chairs, typing in just the keyword ‘antique’ will return all websites that use the word antique, and typing in the keyword ‘chair’ by itself will return all websites that use the word chair. But typing in both keywords will only return websites that use both words. The more keywords you add, the more targeted will be the websites returned to you. So adding ‘British’ to ‘antique’ and ‘chair’ will only return websites that have all three words in them.

Exercise 10

How could you adapt this trick of using more keywords to help you look for the Bird family?

Now read the discussion

Discussion

You could choose to enter the keywords ‘bird’ and ‘genealogy’ (the study of family lineages). This will almost certainly eliminate websites about storks and flamingos, or you could add an additional term to ‘bird’ and ‘family’ by specifying ‘bird family history’.

Interestingly, if you have misspelled the keyword ‘genealogy’ as ‘geneology’ some search engines will not match it to websites containing the term ‘genealogy’. Others will respond with the closest word possible. Google, for example, will respond to ‘geneology’ with the message ‘Did you mean genealogy’ together with some websites related to genealogy. Some search engines can't match ‘family’, say, with its plural ‘families’. So if, in a particular search you don't get any matches (called hits), one strategy is to try making plural keywords singular and vice versa. Also remember to check your spelling carefully.

Another useful strategy is to look for phrases rather than individual words. In Exercise 10, I mentioned that you might use ‘bird family history’ to look for information on the Bird family. This might yield a response that includes anything about the animal ‘bird’ using the scientific term ‘family’ and any use in any context of the word ‘history’. However, if you were to enclose the words ‘family’ and ‘history’ in quotation marks (as ‘family history’), the web server will only return websites that contain the word ‘bird’ and the phrase ‘family history’.

SAQ 5

What is a search engine? How does it differ from a browser?
In carrying out a web search, how many computers (at least) are involved?
What makes a computer actually do work?
In what way is a gateway useful?

Now read the answer

Answer to SAQ 5

A search engine is a computer program that uses keywords to help users locate websites containing information they want.
At least two are involved: the user's computer (the client) and the web server.
A program of instructions, stored in the computer, called a computer program.
A gateway provides a pre-chosen set of links on the web for a particular topic. Instead of searching the whole of the web for information, a gateway provides a very focused means of getting information that usually has been compiled by an expert.

4.3 Computer-based activities

4 Computers as tools for finding

4.3 Computer-based activities

Activity 1

This introduces you to search engines. It shows you how to invoke a search engine from your browser and make simple searches for topics of interest.

Click on the 'View document' link below to read activity 1.

View document

Activity 2

This gives you the chance of using some advanced search facilities (such as the two mentioned above) to make more targeted searches.

Click on the 'View document' link below to read activity 2.

View document

4.4 Summary

4 Computers as tools for finding

4.4 Summary

This section described how computers can be used in geographical applications (and in doing so it discussed maps and showed how modern maps are composed of layers of different data).

It discussed the GPS to demonstrate how computers can communicate in order to solve a problem, such as navigation.

It also showed how the geographical data that supports both map-making and the GPS navigation system can be presented in different forms such as a map, a list of directions, a moving graphical display on a navigation device such as a GPS receiver or as spoken directions. The reasons why one form of presentation is preferable over another were discussed: it depends on fitness-for-purpose, i.e. on the requirements of the user and/or the situation in which the information is needed.

Finally the section described how computers can be used to find information on the web. The two activities associated with this section introduced you to gateways and to the simple and advanced use of search engines.

5.1 Genetic databases and disease

5 Computers as tools for working with data

5.1 Genetic databases and disease

Section 2 looked at data and information from two different perspectives: that of the individual and that of commercial organisation. The type of data you have will dictate both why you want to process it using a computer and, to a large extent, how that is done.

This section contains two short case studies whose unifying theme is that the computer and its programs are tools for working with data. The two studies provide an interesting contrast between:

simple data in large and complex structures (which require large and complex programs to handle them), and
complex data which a complex program helps a non-expert to handle in some interesting, creative, flexible ways.

This subsection uses a case study to show how simple data (the four bases in DNA) can be combined in different ways to create a huge and complex collection of information.

What is DNA?

DNA (deoxyribonucleic acid) is frequently in the news for four main reasons.

DNA can be used in crime detection to eliminate innocent suspects from enquiries or, conversely, to identify with a very high degree of probability the guilty.
DNA is now used in medicine to detect the possibility that diseases having a genetic origin may occur in an individual. This enables doctors to prescribe preventative treatments.
It is hoped that discoveries about DNA will yield important new treatments for hitherto intractable diseases and conditions.
DNA can be used to identify victims of disasters, and establish whether people are related.

Figure 12 illustrates the following characteristics of DNA.

DNA has the shape of an immensely long twisted ladder (the famous double helix) in which each pair of chemical bases in the strand can be thought of as a rung in the ladder.
It consists of pairs of chemical bases called adenine (A), cystosine (C), guanine (G) and thymine (T).
The bases (which in Figure 12 are colour coded) can only be paired according to the rules: A to T and C to G.
A ‘rung’ or pair of bases (e.g. A–T) is called a base pair.
A nucleotide is a base pair plus its attached ‘structural’ molecules (i.e. the sides of the ladder).
Sequences of base pairs constitute genes which are the sections of a DNA strand that form discrete units of heredity (such as eye colour).
A complete DNA strand constitutes a chromosome (a human being has 46 of these combined into 23 pairs).
The four letters (A, C, G, and T) representing the DNA bases constitute ‘signs’ symbolising the building blocks of DNA. You can think of a set of signs as a code.

Figure 12 A DNA strand, bases, nucleotides, genes, and a chromosome (a) A small section of a DNA strand as though it were untwisted. Each box represents a base (A, C, G or T). Each pair of bases forms one nucleotide. Several nucleotides make up a gene (shown by brackets) (b) How the strand of DNA in (a) is twisted into the famous double helix (c) A chromosome formed from one DNA strand.

Exercise 11

The English alphabet is a system of signs that consists of 26 letters, from A to Z. There are rules that govern how letters can form words in English. For example, the combination ‘m-s’ cannot be used to begin a word, but is acceptable within or at the end of a word. This limits the number of English words it is possible to form.

Words, and parts of words, can be combined to make longer words. For example, adding an ‘s’ to ‘dog’ makes ‘dogs’, and preceding ‘mill’ with ‘wind’ gives ‘windmill’. Rules also determine that ‘windmill’ is all right, but ‘millwind’ is not.

Considering these facts, how many words do you think the English language has? Now think about things that can be said using the English language: utterances. These consist of words strung together according to a set of rules known as grammar.
How many utterances do you think it's possible to make in English?

Now read the discussion

Discussion

A standard, reputable dictionary will have between 30,000 and 50,000 entries. Even this is only part of the story since most dictionaries do not include slang, dialect words or words that exist for only a very short period of time. Neither do they contain specialised vocabularies that exist in certain professional and trade groups (e.g. among doctors). Thus the likely total vocabulary of English is (at a guess) in excess of 100,000 words.
The number of utterances possible in English is virtually infinite. This is because, even given the rules of grammar, they can vary in length and word order.

Exercise 11 shows how a relatively simple code (signs like the alphabet) can be combined in simple and complex ways to produce an enormous variety of possible ‘products’ (utterances in English).

Exercise 12

Think of the DNA bases (A, C, G, and T) as forming a code similar to the alphabet, i.e. four ‘signs’ that can be combined according to rules to form genes. The genes in turn are combined into structures called chromosomes (i.e. DNA strands) of which the human being has 46 in 23 pairs. Given this structure, a gene is analogous to an English word, a chromosome to a volume of English utterances, and all 23 pairs of chromosomes to the volumes of an encyclopedia.

At a guess, how many base pairs, like A–C, do you think the 23 pairs of human chromosomes have?
What might that answer tell you about how difficult a problem it is to develop a full understanding of the human genetic structure?

Now read the discussion

Discussion

The longest human chromosome has about 263 million base pairs, the shortest 50 million. For all 23 pairs the total exceeds 3.2 billion (i.e. 3,200,000,000).
The base pairs in a gene can vary, which is what gives us genetic diversity. So the problem of trying to understand the genetic structure of humans is roughly analogous to trying to read and understand all the sentences in a huge, multi-volume encyclopedia!

These two Exercises demonstrate that having a simple code is no guarantee of a simple system! What can be produced lies not in the simplicity or complexity of the code, but in the possibilities for combinations and the stringing together of small parts to form larger products. In other words, simple elements of data can generate a huge amount of information.

The human genome

All life is ‘encoded’ chemically in genes. What this means is that the structure of an organism, the organs it possesses, its colouring, and so on are all determined by different genes. A very simple organism may have just a few genes, and a complex one tens of thousands. The ‘map’ of an organism's genes is referred to as its genome. It shows, in essence, which genes give rise to which characteristics or traits of the organism. The word ‘template’ would describe the genome better than ‘map’.

Figure 13 shows the 23 pairs of human chromosomes that constitute the structure of the human genome. These chromosomes contain between 30,000 and 40,000 genes in total. For each human characteristic, such as eye or hair colour, the human genome shows where the genes are that control that characteristic.

Until recently, the idea of mapping the genome of even a simple organism was just that, an idea. The work involved in extracting genetic material, examining it and mapping it to known traits, would be analogous to sitting a dozen people down at typewriters and asking them to write a multi-volume encyclopedia. It could have been done, but it would have been time consuming (and therefore costly).

Why do it? DNA acts like a computer program. Just as programs instruct a computer to produce certain outputs, DNA instructs the body to develop proteins that make up tissues, cells, antibodies, and so on in a certain way. If there is a defect in a person's genetic makeup then problems can occur; for example, that person might be more susceptible than average to certain diseases. Mapping the human genome offered some enticing possibilities:

better understanding of diseases, particularly complex and threatening diseases like cancers;
an understanding of the relationship between different human groups. For example, are we descended from one pair of proto-humans, or did different groups have many different origins?

International effort to map the human genome began in 1995, when it was estimated that the project would require US$3 billion and take eight years. But, due to the development of computer-controlled robotic laboratory techniques and improvements in information technology (IT) systems, the Sanger Centre announced in 2000 the first draft of the human genome.

Figure 13 The human chromosomes. An X and Y chromosome is shown as the final pair, meaning that the individual would be a male (females have two X chromosomes)

Screening for genetic defects

Now that scientists have mapped the human genome, computers can be used to detect genetic defects.

Screening for genetic diseases existed before the application of computers. Family histories were used, together with a knowledge of inheritance patterns and statistics, to determine the likelihood of a couple having offspring with genetic disorders such as sickle cell anaemia.

Some genetic disorders such as phenylketonuria have had simple chemical detection tests available for some time. Once detected, careful control of diet prevents mental retardation, demonstrating the value of detecting the presence of a genetic disease before any symptoms have appeared.

What the computer adds to the screening process is the power to compare very long genetic sequences (i.e. sequences of base pairs) against the human genome in a way that would be far too time consuming (and therefore expensive) to be carried out by hand. Once a particular gene and type of defect has been identified, it becomes possible to develop a test to find out whether a patient has that genetic defect well before any signs of it appear.

Genetic tests are used for several reasons, including:

prenatal diagnostic testing;
testing to predict adult-onset disorders such as Huntington's and Alzheimer's disease;
forensic and identity testing.

Example 5 Breast cancer and genetics

Breast cancer is one of the commonest cancers in women (it occurs in men as well, albeit rarely). The success of treatment following early diagnosis led to a great deal of research in ways of identifying the cancer in the population at large. Some time before the mapping of the human genome it was already known that between 10 and 15 per cent of breast cancers are familial in origin (i.e. groups of related individuals show a greater than average tendency to develop the disease).

Following the mapping of the human genome, it was determined that about one-third of familial cancers are attributable to defects in two genes known as BRCA1 and BRCA2. Now there is a genetic test to determine whether or not a woman whose family history includes a high incidence of breast cancer is carrying these defective genes. If she is, her risk of developing breast cancer over her lifetime is between 56 and 85 percent; and she has a greater than average probability of developing ovarian cancer.

However, there is little point in having a test if there are not corresponding means of providing help. In the case of breast cancer, increased frequency in screening can help detect the cancer at an early stage (and thereby increase the effectiveness of treatment). More controversial is the preventive removal of breast tissues, which imposes a heavy emotional and physical burden without being completely effective. As with so many technological developments, there are costs associated with their use.

It is hoped that using information related to the human genome will lead to ways in which genetic defects can be corrected or their effects lessened.

There are a number of genetic databases that can be accessed over the internet. Using them to detect defects involves searching enormous databases containing genetic sequences which requires huge computational effort.

This case study on DNA has illustrated three main points:

DNA data is coded in a very simple way (with just four letters of the alphabet);
such a simple code can still generate complex, multiple structures;
searching such a structure is a time-consuming task.

SAQ 6

How can a simple code, such as the DNA bases, become such a complex problem for computing?

Now read the answer

Answer to SAQ 6

Although the code is simple, the bases combine in very complex structures called genes (analogous to words in a language) that can be combined into more complex structures called chromosomes (analogous to a volume of a large encyclopedia). Searching for a particular genetic defect in the genetic structure of the human being is not a trivial task. Apart from the size of the search, there are likely to be many instances of the same combination of base pairs (just as searching for the word ‘king’ in the collected works of Shakespeare would yield a large number of hits, including some false ones such as ‘lurking’).

5.2 Art and the common computer

5 Computers as tools for working with data

5.2 Art and the common computer

Art is difficult to define. But all art involves the Exercise of human skill. A natural object, such as a piece of driftwood, a flower, a bird song, can move us to admire it as beautiful or intriguing or comforting, but it isn't art. Artists (be they photographers, painters, sculptors, actors, musicians, authors or dancers) use their skill to transform natural objects, materials or signs (paint, clay, their own body or voice, the sounds of musical instrument, words) into something else: something with value in its own right rather than for the way in which it might be used.

And what, you may ask, do computers have to do with art?

Central to this unit is the idea that a computer is essentially a tool. And because of the flexibility of programming, it is an exceedingly flexible tool. With the right sort of program and appropriate peripheral devices, a computer can be used by artists to produce art. This subsection will examine how computers can be used to produce visual art.

If you examine a photograph, a painting or a view out of your window carefully, you will notice that what you are looking at is, for the most part, incredibly complex. Colours vary across an almost infinite colour spectrum. There are apparent lines or edges, and objects within the view will be clearly or fuzzily defined depending upon lighting conditions and distance from the person viewing the scene.

Exercise 13

If you were asked to develop a coding system that enabled you to store the view from your window in the form of perceptual data in a computer, how do you think it would compare, in terms of complexity, with that of the DNA code?

Now read the discussion

Discussion

DNA has a very simple code: just four values or letters. A scene such as the one I see out of my window at the moment is highly complex. It contains innumerable colours, light and shade, lines and edges, and visual depth, with objects nearby appearing focused and those further away progressively less distinct. So I would say that encoding this for use by a computer would require a complex code.

You may have a somewhat different answer, but your answer should have taken into account the complexity of virtually any scene.

Fortunately, applications for processing graphical data (even complex graphical data like photographs of scenes outside my window) take care of this complexity. They let the user work with such graphical data, not at the level of individual codes, but at higher levels of abstraction, such as deepening a colour's hue, altering the contrast, and so on.

Transforming the natural to the designed

The artist Christine Martell lives in Oregon in the United States and works with beads and visual images. I asked her to describe how she makes use of a computer to create her visual images of flowers and trees. She writes of her work:

I start by finding flowers that are compelling in some way, most often in form and colour. I take photographs with a 35 mm camera having a macro lens.

I'm usually looking for a line that might suggest movement or gesture. I find a place that might be the resting place in the movement, and focus the camera there. Often times the background is out of the focal range.

When I have the film developed, I choose a lab that tends to make the photographs saturated [with little or no admixture of white] and rich. I prefer to bring the colour ‘down’ electronically rather than try to enhance it. I have the prints made in 5 by 7 inch size.

I scan the photograph into the computer, using a simple consumer grade scanner. I copy the image to make a working copy. I keep the original photo scan as a separate file, so I can move back and forth between the images to restore original edges and details.

When I draw into the images electronically using a drawing tablet, I am usually looking to create a dynamic energy; to express a movement and visually emphasise the contrast between that energy and the stillness of the flower. I draw back into the images with my digitising tablet, using Painter software. I hardly ever use filters [standard effects made available by ‘painting’ software, equivalent to using a lens filter on a conventional camera] as the effect is too uniform for my taste. Once in a while, if I need a uniform texture for a background, I'll use a filter… or I might start with a filtered texture, then draw into it.

The computer gives me the freedom to mix the visual effects of media that would not readily combine in traditional media. I also can work through many more ideas electronically.

Figure 14 shows one of Christine Martell's original scanned-in photographs beside her final image. Of course, in a way even her original photograph is art. She has been careful to use her skill to select a viewpoint, a moment and a field of focus, and then to choose a developing laboratory that will do what she needs with the colour saturation. Finally, in order to achieve the result she wants, she uses a drawing tablet with a ‘painting’ program to ‘paint’ effects.

Figure 14 (a) The photograph, already ‘art’, and (b) the completed visual image (courtesy of Christine Martell). She used an ordinary 35 mm camera with a special, but commonly available, lens to produce the original photograph, and a computer, scanner, drawing tablet and a painting program to produce the final image.

Most of us will never be professional artists. However, we can aspire to be creative for our own pleasure and the pleasure of those around us. The computer offers considerable scope for doing this.

Note that Christine Martell uses a standard scanner to scan in her photographs. Having an electronic drawing tablet is more unusual, but these are easily purchased and anyone with sufficient manual control can use one.

Perhaps the biggest advantage the computer gives Christine Martell as an artist is that she can make as many electronic copies of her scanned image as she requires. This allows her to try different effects, freely discard those that she is not satisfied with, throw away mistakes, or use the power of the computer to make many different images from the same original photograph. To do the equivalent by hand using an actual photograph would be far costlier, and some mistakes which are not erasable would require the artist to throw away prints.

The other main advantage of the computer as an artist's tool is that it can produce effects that would be difficult using traditional media. Christine Martell mentions one, i.e. to be able to reduce the saturation of her colours. She can do this selectively to parts of a photograph – something which is virtually impossible using conventional film-developing methods. By choosing to have her film developed in such a way that the colours are deep and saturated, she gives herself the freedom, using her computer, to alter those colours to whatever saturation she desires.

SAQ 7

What characteristic of computer systems enables them to be used creatively? In which part of a computer system does this characteristic reside?
Give an advantage a computer system offers the creative artist and state why it is an advantage.

Now read the answer

Answer to SAQ 7

The flexibility of a computer system is key to being able to use them creatively. It is the computer program that makes such flexibility possible.
It is possible to make many copies of something. This enables the artist to experiment freely, throwing away mistakes or results that don't please, or making many different versions from a single original.

5.3 Summary

5 Computers as tools for working with data

5.3 Summary

This section made an interesting contrast between simple data that generates large and complex structures that require large and complex programs to handle them, and complex data which a complex but easy to use program helps a non-expert handle in some interesting, creative, flexible ways.

The case study on DNA illustrated how simple data (consisting of only four elements) can be combined into very large and complex structures (genes and chromosomes). You learned how such large and complex structures, when stored in databases, present certain computational problems. The difficulty of finding anything in such large databases where data may be very repetitive or partial, or its location not known means that huge computational effort is required, both to build the database in the first place, and then to use it effectively.

In contrast, the second case study examined how complex data, such as the graphical representation of a scene, can be made relatively easy to use by a non-expert. The case study showed how the flexibility of a computer and its ability to make and store multiple copies provides great scope for creativity.

6.1 Controlling things

6 Controlling things; selling things

6.1 Controlling things

As you learned in Section 1, computers can collect, process, store and distribute information. This section shows that they can also be used to:

control machines and simple mechanisms;
conduct a special kind of commerce: selling on the web.

Let us examine more closely that common household appliance, the automatic washing machine. Virtually all such machines sold in the last decade or so are controlled using a microcomputer of some type. Before that, such control was provided by mechanical systems. However, because these had moving parts they suffered from wear, and tended to break down frequently or require replacement. Also, the nature of mechanical control systems limited how complex they could be. Consequently, they tended to be quite simple, and therefore less ‘automatic’.

The main tasks of a microcomputer in a modern washing machine are to:

present an interface to the users that lets them know what possibilities there are and what the current state of the machine is;
allow the user to select one from a variety of predetermined washing programmes;
change some of the parameters (such as water temperature) to suit particular conditions;
initiate, control and finally halt the actions of the machine in accordance with the wash programme selected;
in some machines, ensure that the washing is done efficiently with minimum inputs of water or washing powder, in the interests of reducing resource use and maximising environmental protection;
ensure safe operation of the machine.

Let's examine some of these tasks in more detail.

The user interface

An interface to a washing machine does not need to be like the interface to a personal computer (a user interface is a display/control panel that enables the user to control a machine or interact with a program). It is specific to the task of washing laundry, which involves two things:

displaying the choices that relate to washing laundry (such as type of laundry to be washed, water temperature, and spin speed);
displaying some indication of the state of the machine and/or the programme selected. On the machine control panel shown in Figure 6.1, the displays on the right show:
- the time remaining in the current wash programme;
- a series of lights showing which parts of the programme (wash, rinse and spin) remain to be done.

This machine also uses an audible signal (a periodic beep) to tell the user when the washing cycle is complete.

Figure 15 The control panel (interface) of a modern automatic washing machine. This particular machine also allows the user to select a ‘quick wash’ (for example, when laundry is only lightly soiled)

Choosing programmes and parameters

Another part of the interface shown in Figure 15 allows the user to select one from a variety of predetermined washing programmes, and to change some of the parameters. If I choose the ‘cotton’ programme, for example, the microcomputer's program assumes that I wish to wash this load of laundry at 60°C, use the main wash programme, and spin the washing at the highest speed. Sometimes this programme is fine, but at other times I may want to select the higher temperature of 90°C in order, say, to sterilise the laundry (e.g. nappies), or a lower temperature (e.g. to prevent dark colours fading).

I may also select the pre-wash if my laundry is especially dirty or the additional rinse if a member of the family has sensitive skin which may react to residues of washing powder.

Finally, the microcomputer's program ensures I don't do anything silly. For example, if I select the ‘hand wash’ programme, it will not allow me to change the temperature to one higher than the pre-programmed 30°C.

Exercise 14

What kind of interface would you expect on a very simple microwave oven (one without predetermined programmes)?

Now read the discussion

Discussion

Since power level (e.g. defrost, low, medium and high) and time are important when microwaving food, the user needs to be able to select these two parameters.

Typically, a microwave interface will have buttons or a dial for selecting the power level, and a numeric keypad or dial for setting the time in terms of minutes and seconds. The display might indicate the power level chosen, and will certainly show the time remaining.

The interface will also have two other important controls: a ‘Start’ button and an ‘Open door’ button.

You may have said something a bit different, depending on your familiarity with microwave ovens.

Ensuring safety

Ensuring that a user can't choose a wash temperature that's too hot for the ‘hand wash’ programme is an example of ensuring safety. In other words, the washing machine microcomputer is trying to prevent the user making choices that are not sensible. Of course, I could put a load of delicate washing in and choose the ‘cotton’ programme which has a temperature of 90°C. The computer program controlling the machine has no way of knowing that I've put silks or woollens in and not cottons. The worst that would happen, however, is that I would ruin some expensive clothing due to my own negligence.

What about the safety of the user? A washing machine could be dangerous if anyone could put their hand into the drum when it was moving, or when the water was very hot (anything over 40°C can scald), or when the water level is high enough to spill out of the door. The programme on my machine does allow the user to open the door to insert additional items during the cycle, but only when safety conditions are met (drum not moving, water not too hot, water not too high). It is incumbent on the designer of any such system to ensure that basic safety requirements are met. While it may not result in serious harm if, for example, one can open the door when water is above the level of the bottom of the door, customer satisfaction would surely plummet were this to happen.

Some computer-controlled applications (e.g. controlling a flying aircraft) have to go further towards ensuring that an operator doesn't jeopardise situations due to negligence. These are not discussed in this unit, but you should be aware that they exist. They are called safety-critical systems, which means that serious harm or loss of life could occur if these systems break down, or do not function properly.

Exercise 15

It is common in modern cars to have central locking. This usually involves pressing a button on a key fob and sending a signal to the car from a short distance which locks or unlocks all doors simultaneously. A button on the control panel may work in a similar way to lock and unlock all the doors from inside.

Can you identify any safety situations that would affect the lock-control program in the car's microcomputer?
What kind of information might a driver need about the door locks?

Now read the discussion

Discussion

It might be dangerous to allow someone to unlock the doors while the car is in motion. For example, a child might press the button on the control panel, unlocking the doors, then accidentally open the door and fall out. With very small children, it might be dangerous for the child to be able to unlock any door (even when the car is stationary) without the driver knowing. Thus one safety consideration might be to ensure that it is not possible to override child-proof locks accidentally or through carelessness.
The driver might simply need a light to tell him or her whether the locks were engaged or not.

Controlling the machine

The major task of a washing machine microcomputer is to control the actions of the machine in accordance with the wash programme selected. To do this, the computer is electrically attached to a variety of:

actuators that cause mechanical parts of the system to work;
sensors that sense the state of some aspect of the machine, such as water temperature.

There is an actuator to open or close the water input valve. Another controls the turning of the drum, and another the pumping of water through the machine. There is also one for pumping the water to the drain and one for controlling the water that washes through the tray holding washing powder and fabric softener. Lastly, there is an actuator that turns on a heating coil if the water temperature is below the desired temperature for the wash.

As regards sensors, my machine has one to check water level, and another to check water temperature. It also has a sensor that weighs the dry laundry at the start of the cycle, providing data that the microcomputer program uses to determine how much water to use for each wash. This enables my machine to optimise water use, and hence conserve resources (water and the electricity to heat the water).

Exercise 16

The general wash programme cycle on my machine goes through the following steps.

It weighs the dry laundry once the door is shut and the ‘Start’ button is pressed.
It determines how much water should be used and opens the valve.
It pumps water through the washing powder tray for a period of time to flush the powder into the drum, and then pumps the water directly into the drum.
It locks the main door when the drum is in motion, or when the water level is higher than the bottom of the door (a safety feature).
It heats the water to the correct temperature for the programme and point in the washing cycle.
It turns the drum and recycles the water onto the laundry for the duration of the washing cycle.
It drains the water from the drum.
It spins the laundry at the correct speed for a certain time.

The programme stops.

For each of the eight steps listed above, list the actuator or sensor involved.

Now read the discussion

Discussion

The weight sensor.
The valve actuator.
The actuators for the water pump and for the valves channelling water in different ways through the machine.
The actuator for the door lock and the water level sensor.
The water temperature sensor, and the actuator for the heating coil.
The actuator for the motor spinning the drum, the actuator for the water pump and the actuators for the valves leading into and out of the drum.
The actuator for the pump and the actuator for the drain valve (or the actuator for water channelling, depending on the design or type of the machine).
The actuator for the motor spinning the drum and the actuators that drain water from the drum (as in point 7).

SAQ 8

What role do computer control systems play in many mechanical devices?

Now read the answer

Answer to SAQ 8

They manage sensors and actuators to control the actions of mechanical devices such as cars, microwaves and washing machines.

They provide interfaces that enable the user to control the workings of the machine.

They control the machine's actions in response to the user's choices and the state of the machine.

6.2 Selling on the web

6 Controlling things; selling things

6.2 Selling on the web

The web is fast becoming a medium for selling everything from books to clothes, gardening tools to beauty products, investment advice to travel services. Web-based selling seems to be concentrated in three main categories of company:

existing catalogue sales companies which have put their catalogues online to allow customers to buy using the web;
existing companies whose products are largely information and which have used the web as a means of providing a personalised service or one with a very quick response;
companies which have started from scratch using the web as their only sales medium.

Of these companies, the most successful financially have been those in the second category. For example, Pergamon Press, which publishes many professional journals, has moved to making all its journals available electronically. Consequently, not only is its selling done over the web, so is its distribution! The company still charges a subscription fee which remains more or less equal to what it was before Pergamon began using the web. However, most subscribers (largely the medical and legal professions) have chosen to use the convenience of electronic delivery, and this has drastically reduced printing, warehousing and distribution costs for Pergamon.

One successful company in the first category is Lakeland. This is a British company which began by providing plastic bags for the farming industry, and now sells a wide variety of household items, food ‘treats’, and seasonal items for Christmas and summer. The company ran an established mail order business before venturing onto the web, and it also has a chain of shops in major UK towns. Thus the venture onto the web was, for Lakeland, an extension into a new selling medium. The company already had expertise in presenting their products from their mail order catalogue business. It also had an established infrastructure of suppliers, warehouses and links to delivery companies.

In the last category of companies, one of the success stories of the web has been the online bookseller, Amazon, which has expanded into all kinds of consumer goods such as smaller electronics, videos and DVDs. It also acts as an agent for sales of second-hand goods. So if a book is out of print, you may be able to buy it second-hand through the Amazon website.

Using a sales website

A visitor to a sales website is usually able to:

browse through the details of the goods for sale;
search for a particular product;
check on the availability of goods;
read reviews of the products by other purchasers;
register to receive newsletters which detail new items of interest;
buy products using credit or debit cards, and in some cases, other payment methods such as cheques.

Some sales sites also allow the user to:

see what items are most popular;
check the status of their order.

An indication of what Lakeland's website offers can be gained from its home page shown in Figure 16.

Figure 16 The Lakeland home page offers product and keyword searches, a quick way to browse various categories of products, what's selling best, and a product of the day

Exercise 17

The Lakeland website offers both a product search and a keyword search.

Describe what you think are the differences between these two types of search.
Why should there be two ways to search?

Now read the discussion

Discussion

1. A keyword search allows the user to type in words, such as ‘clothes storage’ and the search engine will look through Lakeland's website for products which fit this description. A product search is associated with the catalogues that customers receive. The product numbers in the catalogue can be used to access a product very quickly. For example, typing in ‘5692’ will display the product designated by that number.

2. The two types of search serve different customers: those who are interested in a particular type of product (keyword search) and those who have their eyes on an actual product (product search).

Database servers

To be able to search a website like Lakeland's requires not only a web server but a database server. Like a web server, a database server is a computer that responds to requests from other computers. Its task is to find and extract data from a database.

The web and database servers form part of a distributed system. This means that separate computers exchange data and information across a network (in this case the internet) to produce results for a user. For example, suppose I use the keyword search to ask for ‘kitchen cleaners’. This request is transferred to the web server, which has an index of products which can be categorised as kitchen cleaners. It then sends these product numbers to the database server, which locates the correct items in the product database and returns information about them (pictures, description and price) via the web server to my browser.

Compared with the simple data from which the complex DNA database is built, the data processed by the database servers at a company like Lakeland is complex (text, graphics, pictures).

Exercise 18

For a company like Lakeland:

what are its customers' information requirements?
what are the company's information requirements?

Now read the discussion

Discussion

Customers are likely to want to know:
- the items for sale;
- what items look like;
- details about performance;
- cost;
- other information, such as availability, guarantees, delivery costs, and time of delivery.
Lakeland's requirements will be much broader and include information relating to:
- product suppliers;
- wholesale cost;
- availability and delivery arrangements;
- its own storage and distribution system;
- who buys products from Lakeland and why;
- what other products such buyers might be interested in;
- where there might be sufficient customers to warrant opening a new shop;
- hiring, training, promoting and retaining staff;
- competitors and what they offer that Lakeland does not;
- accounts and finance;
- legal matters such as product and supplier liability, employment law, contract law.

Your answer will probably differ from this list, but you should have a number of points that are similar to items above.

Let's see how Lakeland's system addresses some of these requirements in terms of the data they store in their databases. This will include:

information about customers:
- names and contact details,
- credit card information,
- the passwords (if any) they use to gain access to the Lakeland website;
information about their products for sale:
- pictures,
- specifications,
- price,
- special offers;
the current stock (inventory) of a particular item;
the position of a product in terms of its popularity;
orders that have been made:
- when they were made,
- when they were or will be dispatched,
- whether the full order can be satisfied from stock.

What is interesting is that although the data listed above is quite ‘rich’ (i.e. complex), the processing required to extract the data is not very complicated. For example, it takes very little computational effort to extract a customer's current order. All that is necessary is for the area of the database containing order details to be searched for a match with the customer's name information or an order number.

Security: are my credit card details safe?

Many people now shop regularly on the web. However, many others don't because they fear that an unscrupulous person could obtain their credit card details. They also fear that if they provide their names and addresses to a firm on the web, they will be bombarded with junk mail (or its electronic equivalent, junk email). Some worry that, since anyone can put up a website, the seller may be bogus and no goods will appear after the sale has been completed or won't be as advertised.

Consequently, other important issues raised by this case study are security and trustworthiness. The internet is a remarkably open medium. It does not take too much effort to ‘capture’ the data that flows along communication lines. Someone could theoretically read your credit card details as they are transmitted between your computer and that of the seller. (I use the term ‘theoretically’ because there exist techniques which enable the data to be transformed into a form which would be virtually impossible to read.)

You can be reasonably confident of buying from a website if it displays one of two things.

The address shown in the bar at the top of the screen should start with ‘https’ instead of ‘http’. The letter ‘s’ means you are connected to a secure web server using techniques to protect your details from electronic snoopers.
An icon representing a small key is present. This also indicates that the web server you are connected to is a secure one.

Another safety precaution is to deal only with web sellers you know are reputable. Consumer organisations often have schemes for accrediting web sellers who are legitimate and secure dealers. Friends and neighbours may also be able to recommend reputable and secure web sellers.

SAQ 9

Is web selling, as practised by a firm like Lakeland, an example of a distributed system? Explain.

Now read the answer

Answer to SAQ 9

Yes, it is a distributed system. It consists of user PCs, web servers, and database servers, with data and information being transferred between them using networks (in this case the internet).

6.3 Summary

6 Controlling things; selling things

6.3 Summary

This section examined how computers can be used to control machines. It used the household washing machine as a case study and explored how the microcomputer contained in such a machine is programmed to:

provide an interface for the user to operate the machine;
control the way the machine carries out the operations chosen by the user.

The washing machine case study also illustrated the necessity of building safety features into computer-controlled mechanisms.

Computers are also used to support selling goods and services via the web. A case study of a successful company showed what the information requirements for such a system are, and examined how two or more computers can cooperate as part of a distributed system to satisfy these requirements in a way that is secure.

7.1 What have you learnt in this unit?

7 Unit summary

7.1 What have you learnt in this unit?

This unit began by exploring some basic issues involving computers:

the nature of data and information;
why human beings need (and want) computers;
the prevalence of computers in modern life.

The unit looked briefly at how a computer-based society affects the average person who (whether he or she knows it or not) has a persona that consists of data about them held by many diverse organisations.

Much of this unit consisted of case studies illustrating the possibilities for computer use. They raised some of the issues posed by computing technologies, such as:

the distinction between data and information;
what computers can do with data to produce information;
how computers can be used to work with data and search for it, control machines, and support commercial operations.

There are a number of themes running through this unit.

Data requires encoding.
In order to function, a computer requires data which may be stored in databases.
Data has to be transmitted from place to place.
At the heart of a computer system there are one or more programs.
Many current computer systems are distributed, in that they consist of a number of computers which cooperate and communicate with each other in order to function.
Information has to be fit-for-purpose.
Security and trustworthiness are major concerns with many systems.
Computer systems also have drawbacks and adverse effects. They also have social, political, legal and ethical implications.

You should be able to define the following terms in your own words.

case study	hit
computer	information
computer program	internet
computer system	keyword
data	parameter
database	perceptual data
database server	search engine
distributed system	sensation
gateway	sign/symbol
global positioning system (GPS)	World Wide Web (the web)

Do this

Now you have completed this unit, you might like to:

Post a message to the unit forum.
Review or add to your Learning Journal.
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Acknowledgements

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

Figure 1 The National Gallery, London;

Figure 3 NOAA-AVHRR image provided courtesy of the Canada Centre for Remote Sensing, Natural Resources Canada;

Figure 4(a) Map extract produced by FWT and reproduced with the kind permission of the Association of Train Operating Companies;

Figure 4(b) Reproduced from multimap.com. Ordnance Survey map with permission of Ordnance Survey on behalf of The Controller of Her Majesty's Stationery Office, © Crown Copyright. ED 100020607;

Figure 6 Lowrance Electronics Co;

Figure 7 Garmin International Inc;

Figure 8 www.theaa.com. Reproduced by permission of the AA;

Figures 9(a), 9(b), 10(a)(a) Google Inc;

Figure 10(b)(b) Lycos UK Ltd;

Every effort has been made to contact copyright holders. If any have been inadvertently overlooked the publishers will be pleased to make the necessary arrangements at the first opportunity.

Related educational resources

Thu, 31 Jul 2008 10:18:08 GMT

This is a list of all the Related educational resources for the unit M150_2_1.0 - An introduction to data and information