Over the last few decades there have been many advances in technology in our homes. Electronic technology has been available for almost a century, and from an early stage made its impact in the home with the introduction of broadcast radio. This provided one-way communication into the home, and later the telephone brought two-way communication. Then came the television bringing entertainment and information to the home. These changes revolutionised home life in the second half of the twentieth century, but it was the invention of the transistor and the integrated circuit, which led to digital technology, that dramatically accelerated the change. All of a sudden previously undreamt-of processing power became available all appliances became intelligent . Moore s Law, defined by Charles Moore of Intel, says that the processing power of silicon integrated circuits doubles every two years (and usually the price halves). By way of comparison, the human brain evolved around ten million times more slowly than the silicon chip.

We now live in a digital age. Digital media such as CDs, DVDs, digital cameras, webcams and camcorders are now commonplace. Around 50% of us use PCs at home. Household appliances have digital processing to provide powerful capabilities and enhanced user control. Household devices such as set-top boxes, CD players and even cameras probably have more computing power than was used in NASA rockets to send men to the moon. Why on earth do we need it?

One of the principal uses to which digital technology is put is