An Introduction to Digital Media
Book by Tony Feldman; Routledge, 1997 part 3

This is more than playing with words. Seeing digitisation as evolution encourages us to believe we can look ahead, even guide and influence the pace and direction of its impact on our lives. Evolution is predictable and is therefore something worth analysing. True revolution-if there is ever such a thing-is impossible to call. So, if we agree that we are presiding over digital evolution, we can at least take a stab at understanding where it is taking us and how it might get there. This book, after all, is worth attempting! A fundamental belief in an evolutionary world returns us to the idea that books-like the digital age-are built on antecedents. Some of this book's past has already been outlined. But it is worth concluding with the antecedents that cannot be crystallised so easily. During the fifteen years I have been involved in digital media, I have learned an immense amount from industry colleagues. Many have been untiringly generous with their time, explaining aspects of digital media development that have been difficult for me to grasp. To all of those many people-past and present-all colleagues and friends in the same basic endeavour, I would like to express warm thanks and appreciation. I hasten to add that the good bits in this book are due to their aid and the errors and omissions are entirely my own responsibility!

I also acknowledge with thanks the kindness of my newsletter publishers. To Interactive Media Publications, thanks for allowing me to make some use of articles I have written for Interactive Media International, the monthly publication I have had the delight of editing with my valued colleague, David Powell, since 1990. To Pira International, similar thanks for permitting me to draw upon some of my regular contributions to their periodical, Publishing Technology Review. Lastly, I must thank my children, Sam and Hannah, for reminding me daily that there is a sense in which the world is invented afresh every time the sun rises and that there is no end-nor should there be-to the pleasures of exploring and discovering that world.
Tony Feldman London 1996

CHAPTER 1 WHAT DIGITAL REVOLUTION?
We have already dispatched the idea of revolution and settled for seeing the move to digital media as a process of evolution with potentially revolutionary impact on our lives. But the word 'revolution' remains on all our lips. Leaving the semantics aside, what we are really expressing with the use of the word is not an analysis of whether digitisation is the result of a discontinuity in technological development but a less rigorous, general sense that something truly remarkable is taking place which is likely to transform all our lives and-perhaps, more profoundly-the lives of our children. The idea of digital revolution is implicitly an image of humankind stepping through a doorway into an unknown and fundamentally changed future. And it is a one-way journey, a doorway through which we can never step back to return to the comfortable media certainties of the past. However, we need to begin any inquiry about the future impacts of digital media by understanding the starting point of the whole process. It can be summed up in a very few words. The digital revolution is being forged by an accelerating move from a world familiar with analogue media to a world that will be increasingly dominated by digital media. This, then, is the key-a shift from analogue to digital. To make sense of that simple statement, however, we need to know what analogue and digital mean and, most important, why they are different. After all, the revolution is in the difference.

ANALOGUE AND DIGITAL INFORMATION
A good way of getting a sense of what analogue information and digital information are is to imagine 'analogue' as an expression of our experience of the real world while 'digital' expresses a world belonging exclusively to computers. Whether we know it or not, therefore, we are all familiar with analogue information. Typical examples of it are the continuously varying intensities of natural light, the meanders in an audio record's groove, the variations in an electrical current and the mechanical fluctuations in the air which we interpret as sound. The information embedded in an analogue signal therefore is always built into some continuously varying value which can be measured. By measuring it and responding to its continuous variation, we extract the information it contains. When we listen to music, for example, our eardrums vibrate with the rhythm of changing air pressure. This creates a signal in the auditory nerves which is interpreted by our brain as the pleasing notes of an orchestra. Vision is a response to changing values in the intensity and wavelengths of light on the retina of our eye and transmitted to our brain by our optic nerves for decoding and interpretation.

Another familiar example is an old-fashioned wristwatch. When we glance down at its face we see hands sweeping across the dial at various speeds. They move continuously, covering every part of the dial at some stage of their journey. We judge the time of day by the relative positions of the hands against the scale of hours, minutes and seconds printed on the watch face. This kind of information display is analogue. We read the message of our watch by looking at a constantly changing display. There are no gaps in the information. It is a continuous flow. This is the fundamental nature of the analogue world. Digital information is different. Its character is essentially discontinuous. Far from reflecting continuously varying values, digital information is based on just two distinct states. In the digital world, things are there or not there, 'on' or 'off'. There are no in-betweens. Digital computers talk in a language called binary code. It consists of just two symbols, the digits 0 and 1. Everything a computer does, it does in this starkly simple language. Significance in the information is created by placing the symbols in different orders. In other words, the sequence 00011000 means something different from 00010100. A rich and powerful language is built up in this way. In computer jargon, each of these binary symbols, either 0 or 1, is known as a bit (a contraction of 'binary digit'). A character of computer information-the smallest information element carrying significance in itself-usually consists of eight bits arranged in a characteristic sequence. The overall sequence is called a byte.