The pace of technology is such that what was deemed cutting edge 15 years ago is generally considered obsolete today.

For households this has been evident in the steady migration from analogue to digital: vinyl gave way to CDs, audio cassettes to minidisks and video tapes to DVDs.

The television industry is facing similar problems with an ongoing project to transfer its archive footage from obsolete videotape to current tape formats or even digitised.

When planning Project Gutenberg, the internet archive of free electronic books, its architect, Michael Hart, recognised the problem.

He warned: "Alice in Wonderland, the Bible, Shakespeare, the Koran and many others will be with us as long as civilisation.

"An operating system, a program, a mark-up system will not."