Just as a denary number system uses ten different digits (0, 1, 2, 3, â€¦ 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 2Â°, which is 1. The ne
Author(s): The Open University

A very straightforward way of finding binary codes to represent positive integers is simply to use the binary number that corresponds to each integer. This is because every positive integer in the everyday number system (known as the decimal or denary system because it uses 10 different digits) has a corresponding number in the binary number system.

As you will see later, in Section 7 of this course, just as arithmetic (addition, subtraction, etc.) can be performed on everyday denary nu
Author(s): The Open University

A computer is designed to do the following things:

• receive data from the outside world;

• store that data;

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

• present data back to the outside world.

In the next few sections I am going to examine in more detail the data that a computer receives, stores, manipulates and presents. I
Author(s): The Open University

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

Author(s): The Open University

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

A CD-ROM (Compact Disk Read Only Memory) uses a laser-based optical form of storage. This type of disk has been used for many years to distribute music and computer software. A CD-ROM drive is needed to read the disks. Data is locked into the disk during manufacture, and cannot afterwards be changed.

There are two other types of CD device for computers: CD-R (CD-recordable) and CD-RW (CD-rewritable). With the right sort of CD drive in your computer, you can 'burn' data (that is,
Author(s): The Open University

The network is a communication channel in that it conveys data from the transmitter to the receiver. The network may also manipulate data in some way, and it may also store or retrieve data.

In a mobile phone system, the network conveys the message from User l's handset to User 2's. It will also store the identity of User 1 and the duration of the call. This data is used to work out the amount to charge User 1, which is a form of manipulation of data. A network can be very comple
Author(s): The Open University

The diagram in Figure 6 shows that, for communication to take place, there needs to be some means of conveying the message between the sender and the recipient. I am now going to look at the essential components of 'means of conveying a message'. In other words, I shall treat 'means of conveying a message' as a system and look at
Author(s): The Open University

Music in UIs is relatively undeveloped, except in games and specialist packages designed for composers and musicians.

Some operating systems have a signature tune that is played automatically when they are loaded. This informs the user that the operating system has loaded correctly and creates a sense of identity, but can be annoying for the user if they have to listen to it repeatedly. A development on this use might be to signpost different parts of the program using musical clips.
Author(s): The Open University

The use of sound is becoming increasingly common, particularly for the following types of application.

• Applications where the eyes and attention are required away from the screen. Relevant examples include flight decks, medical applications, industrial machinery and transport. If you are a runner, you may have a heart rate monitor that allows you to monitor how fast your heart is beating. This is often indicated by an auditory beep, which speeds
Author(s): The Open University

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## Study another free course

There are more thanÂ 800 coursesÂ on OpenLearnÂ for you t
Author(s): The Open University

Most browsers allow you to keep a record of links to websites that you have found useful. These are called 'Bookmarks' in Firefox and 'Favorites' in Internet Explorer, and may have other names, such as a 'Hot List', in other browsers. For convenience I've chosen to call them bookmarks. Browsers usually offer the facility for organising the bookmarks into folders and sub-folders so that you can keep track of them as your collection grows.

You may well have a collection of bookmarks alrea
Author(s): The Open University

What do you do if you don't know the URL of the website you are looking for, or haven't been able to browse to it? The Web is not like a library â€“ it isn't carefully organised and catalogued, and it is growing all the time. Luckily, there are search sites that can help you find what you want.

## 2.3.1 Portals

Author(s): The Open University

Liz Bennett and Jon Rosewell

Author(s): The Open University

The versatile tiny transistor is now at the heart of the electronics industry. In the video clips you have seen the history of the incredible shrinking chip, its Scottish connections, and an explanation of the physics that make chips work as well as a reconstruction of making a transistor using the crude techniques of yesteryear.

Author(s): The Open University

There are a large number of books that have been written on e-commerce, many of which are of varying quality. I have found three useful. The first is by Kalakota and Whinstone (1997). It is an excellent introduction to both the technologies and applications involved in electronic commerce. Kalakota has also written a book on electronic commerce which avoids many of the clichÃ©s and which concentrates on unglamorous areas such as supply chain automation (Kalak
Author(s): The Open University

This free course provided an introduction to studying Education, Childhood & Youth qualifications. It took you through a series of exercises designed to develop your approach to study and learning at a distance and helped to improve your confidence as an independent learner.

Author(s): The Open University

These are sites on the web which run conventional auctions. There are two types of auction: those that are carried out in real time, where participants log in to an auction site using a browser at a specified time and bid for an article until the highest price is reached and no other bids are forthcoming. The other type of site â€“ and the most common â€“ is where an item is offered for sale and a date advertised after which no more bids are accepted. Such sites make a profit from two sources
Author(s): The Open University

After studying this course, you should be able to:

• detail what is meant by the term â€˜e-commerceâ€™

• examine some typical distributed applications

• detail some of the problems that are encountered when developing distributed applications

• describe briefly some of the technologies that are used to support distributed applications

• show how some of the technologies detailed in the course are used in concert to realise a typi
Author(s): The Open University

This course draws attention to the value of a sociocultural understanding of spoken language in the processes of teaching and learning. It focuses upon how language can be used for persuasion, control and argument, and how dialogue can act as an aid to development. Along with some background reading and activities this course offers opportunities for the evaluation of some selected classroom talk.

This OpenLearn course provides a sample of postgraduate study in Author(s): The Open University