Presenting information
Tables and charts are a great way to present numerical information in a clear and concise form. This free course, Presenting information, explains how to use the Windows calculator to carry out basic operations and calculate percentages. You will then learn how to use charts and tables to represent and interpret information. Author(s): Creator not set

We will want to distinguish between statements that are true and statements that are false. Another fundamental form of data allows us to do this. This form of data consists of just two values, which we shall write as true and false.

Not all texts use the same notation: some use T and F; others may use 0 for false and 1 for true (or the reverse!).

We may refer to true and false as truth values, or Boolean values
Author(s): The Open University

The AND operation combines two binary words bit by bit according to the rules

• 0 AND 0 = 0

• 0 AND 1 = 0

• 1 AND 0 = 0

• 1 AND 1 = 1

In other words, only when both bits are 1 is the result 1. You may find it helpful to think of it this way: when one bit is one and the other bit is 1 the result is 1.

Author(s): The Open University

In Section 2.4 you saw how to find the 2's complement representation of any given positive or negative denary integer, but it is also useful to be able to find the additive inverse of a 2's complement integer without going into and out of denary. For instance, 1111 1100 (−4) is the additive inverse, or 2's complement, of 0000 0100 (+4), but how does one find the additive inverse without converting both binary integers to their denary equivalents?

Author(s): The Open University

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
Author(s): The Open University

After studying this course, you should be able to:

• understand the basic physics that make chips work

• define Moore's Law.

Author(s): The Open University

Except for third party materials and otherwise stated (see terms and conditions), this content is made available under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 Licence

Figure 1 ENIAC Computer. Photo © Science Photo Library

Rozin, D. ‘Wooden Mirror’,
Author(s): The Open University

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Author(s): The Open University

But if all the data and computer instructions within a computer are represented by 1s and 0s, how can this limited set of conditions be used to represent, for instance, every letter of the alphabet that might be typed into a computer from a keyboard? Activity 4 showed that there are four possible combinations of 1s and 0s
Author(s): The Open University

I have just indicated that a processor is made up of millions of electronic components manufactured as one very complex circuit. The majority of these components act as switches that can exist in one of only two states, either on or off. The states of certain switches tell the processor what instructions to carry out. Also when a processor is running a program it is altering the state of other switches, switching them on and off many, many times a second.

To represent more easily what i
Author(s): The Open University

So what do these devices that are manufactured in such vast quantities look like? Processors are manufactured as integrated circuits. Essentially they are circuits, around the size of a fingernail, which contain many millions of electronic components manufactured as one very complex circuit. Figure 4(a) shows how a processor manufactured as an integrated circuit is packaged so it can be used as a component in an electronic circuit. The pins of the package are connected to the integrated circu
Author(s): The Open University

There is not a lot published on distributed development paradigms. The book by Coulouris et al. [2] indirectly introduces some of the paradigms introduced in this course. Lynch's book [3] on distributed algorithms is full of algorithms which are message passing based. The book by Patzer and 14 others [4] is a good practical introduction to many of the technologies detailed in this course. One of the few current books on JavaSpaces has been writt
Author(s): The Open University

This form of technology, like the hub and spoke approach, allows the broadcasting of messages to a number of receivers. Some of the implementations of bus architectures are rooted in multicasting, a technique which allows data to be broadcast to a number of clients. However, some, like the industrial example iBus detailed later in this course, are a sort of software implementation of an Ethernet, where objects are sent down a bus and only processed by any receiver that requires the obj
Author(s): The Open University

A B2B exchange is a website or collection of websites which make the process of carrying out business to business transactions much easier. Under this banner comes sites which enable multiple companies to procure services and products from each other; help businesses form temporary alliances to carry out activities such as joint marketing or project bidding, and enable a marketplace in raw materials to function.

Author(s): The Open University

The aim of this section is to look at some of the business models which have been used to drive internet applications. A business model is a high-level description of an application type which contains all the common features which can be found in specific examples of the model. For example, one of the most popular business models is the e-shop which describes a website that sells products. The model is general in that it does not describe the item that is sold or the mechanisms that a
Author(s): The Open University

The first application I shall describe is that of an online bookseller. Such a book sales system would carry out a number of functions:

• It would allow the user to browse through a catalogue of books.

• It would allow the user to browse through a list of the most popular books, with the list being updated every hour.

• It would provide the facility whereby a user can buy books and add them to a notional shopping basket.

Author(s): The Open University

These are sites which provide free email facilities; often they provide other facilities such as sending anonymous mail and constructing mailing lists. Such sites are valuable to users who are too impecunious to be able to afford conventional mailing software and to frequent travellers who can access such sites anywhere in the world. Their main disadvantage is that they tend to be slow compared with conventional mailing utilities such as Microsoft Outlook and Eudora.

Author(s): The Open University

These sites are a variation on link checking sites. Here, the customer is notified not when a web document becomes unavailable, but when the document is changed. For example, the customer might be interested in a particular page which advertises some holiday package offers to a particular destination and wants to keep abreast of any changes to the page which might signal the fact that a new improved offer has been added.

Author(s): The Open University

The next example is probably the one that you expected me to introduce first: that of selling goods over the internet. However, I deliberately introduced supply chain management first since it is an area where companies are making huge savings in their investment in internet technology. The investments in retailing using the internet (e-tailing) are only gradually being realised.

The archetypal e-tailing application Amazon is renowned for the fact that it only sells books over th
Author(s): The Open University

Before looking at the wide variety of e-commerce application areas that have flourished over the last decade in more detail, it is worth looking at one which may not be familiar to a reader, but which saves companies huge amounts of resources. The application involves a supply chain. A supply chain is a set of relationships between a number of companies who have a symbiotic relationship with each other in that one company supplies commodities or services to other companies which, in tu
Author(s): The Open University