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2.2 Summary

Social scientists need to stand back, to view common sense or ‘what everybody knows’ from the perspective of a stranger. Common sense about social problems such as poverty involves a process of social construction, drawing on a repository or storeroom of underlying theories and assumptions. Common sense has been built up over time, carrying with it traces of earlier understandings which are also brought into discussions of new issues and debates. Common sense is itself divided, reflecting
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7.4 Multiplying 2's complement integers

Multiplication can be thought of as repeated addition. For instance, in denary arithmetic

7 × 5

can be thought of as

7 + 7 + 7 + 7 + 7

There is therefore no need for a new process for the multiplication of binary integers; multiplication can be transformed into repeated addition.

In multiplication the result is very often much larger than either of the two integers being multiplied, and so a multiple-length representation may be needed to hold the result of a mu
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3.4 Input and output considerations

CCDs are not inherently able to detect colour, only brightness. So it is necessary to rely on the fact that any colour of light can be made up from the three primary colours of light: red, blue and green. (Note that the three primary colours of light are different from the three primary colours of pigments.) Each CCD in the array is therefore overlaid with a red, blue or green filter and so detects the brightness of, respectively, the red light, the blue light or the green light falling on it
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2.4 Representing numbers: negative integers

In Section 2.2 I showed you how integers can be encoded if they are known to be positive, treating the integers in the kitchen scales as if they were known to be positive. However, if the user invokes the ‘add-and-weigh’ function on the scales while there is an object in the scalepan and then removes th
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2.2.2 Positive integers: binary numbers

Just as a denary number system uses ten different digits (0, 1, 2, 3, … 9), a binary number system uses two (0, 1).

Once again the idea of positional notation is important. You have just seen that the weightings which apply to the digits in a denary number are the exponents of ten. With binary numbers, where only two digits are used, the weightings applied to the digits are exponents of two.

The rightmost bit is given the weighting of 2°, which is 1. The ne
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12.2 Bytes of data

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

A byte of data can represent many different things in a co
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9 A stand-alone computer

The computer you are using for your studies is called a personal computer or PC. Although you have an internet connection for use in this course, your computer can probably also be used as a stand-alone computer. Your PC may be a desktop computer or a notebook computer (sometimes known as a laptop computer). Usually a desktop computer comes with separate devices such as a monitor, a keyboard, a mouse and speakers and it runs on mains electricity. Notebook computers
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5.3 Accessibility

In Section 5.1 you assessed the usability of Figure 11, the noticeboard in a public park. For a visually impaired person, that noticeboard might not be usable at all, as you may have commented. This raises the issue of accessibility. Accessibility relates to how well a service is ada
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Acknowledgements

Except for third party materials and otherwise stated (see terms and conditions), this content is made available under a Creative Commons Attribution-NonCommercial-ShareAlike 2.0 Licence

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

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4.6 Lineage linked data

Earlier you saw how a genealogical database records relationships between people. A lineage linked database allows queries such as ‘Ada Rosewell the daughter of John Rosewell’ and makes possible the creation of family pedigrees and other charts. For example, the pedigree chart below shows how Alcimenes was the son of Jason (the Argonaut) and Medea and the grandson of Aeson and Alcimedes.

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5.4 Set-up, maintenance and power requirements

Issues for set-up and maintenance include:

  • Cost (what are the costs of setting up and maintaining the technology?)

  • Availability of components (are components readily available?)

  • Interoperability (will devices from different vendors work together?)

  • Continuity of supply (will components still be available for a reasonable period in the future?)

Because of its greater range and complexit
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7.2 Difficulties in navigating e-commerce sites

People who are new to computing sometimes find the process of online ordering baffling and frustrating. They get ‘lost’ in the process – for example, by putting something into a virtual shopping cart and then remembering that there's something else they need to look for. So they return to the search engine or the catalogue and then can't find the cart. These kinds of commonly experienced difficulties can be addressed by good and adaptive site design, but still a disturbing proportion of
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5 Online shopping – a beginner's guide

Buying goods and services online used to be a minority activity – the preserve of the geeks and the ‘early adopters’ who are willing to try anything new. But in the last few years, online shopping has become a mainstream activity. In January 2003, the Office of National Statistics reported that online shopping accounted for 6 per cent of all UK retail shopping expenditure. The same source reported that UK businesses sold £23.3 billion-worth of goods and services over the Internet in 20
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3 What's going on with eBay

eBay is a huge database with a Web interface. (A database is a collection of information organised in such a way that a computer program can quickly retrieve desired pieces of data.) The database is continually being updated as people add items, and bid for them, and as auctions open and close. The software includes database software and web-serving software and runs on a large cluster of powerful servers. It is a formidably complex system and although eBay had some teething problems in its e
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6.4 Pictures

It used to be thought that a photograph could provide proof of an event – someone could be caught red-handed by a photograph, as proof of their guilt. ‘The camera never lies’, it was said. If you have a digital camera and have been ‘touching up’ photographs on your home computer you will know that this is far from true now. It is easy to lie with a digital photograph.

The idea that the camera never lies has always been a myth, however. As far back as 1917 the photographs of th
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4.4.2 Battery parameters

Now that we have covered some background on electricity, I will return to discussing batteries.

Activity 19

What do you think would be the important characteristics of a battery for a portable ICT device such as a camcorder or a
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4.2.4 CCD light sensor

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

Taylor's introductory comments

Taylor starts with some introductory comments. Notice the informal style he uses because this is essentially a script for a talk to a colloquium. Notice also the other issue that I raised earlier, that Taylor is assuming that his listeners are familiar with terms su
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2.1 Communication technologies

With the Industrial Revolution the idea of ‘news’ developed rapidly, and these days most people in the UK and other developed countries have concept of ‘the news’. We expect to be kept up to date with the news through various sources, and to satisfy this expectation we have the businesses of newsgathering and dissemination of news.

In this section you will be learning about the development of the technologies used for newsgathering and dissemination by reading extracts from a pa
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4.2.7 Some other advice

  • Keep to the subject, and pick the right conference for your contribution.

  • Before you write a message, take time to see what is being discussed and how. Lurking is quite acceptable online.

  • Keep messages short. People don't want to read large chunks of text on-screen.

  • Write a good subject line (title) for your message – people often haven't time to read messages unless the subject line looks relevant.


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