Here's a rough outline of how a series of pioneers developed the technologies you find familiar:
- 1945: Vannevar Bush, Director of the Office of Scientific Research and Development, writes "As We May Think." Writing at the conclusion of World War II, Bush considers how technologies developed for war can be used to further peace. He envisions an electromechanical system based on microfilm and dry photography that can manage all of the data a person needs and help them organize it into knowledge.
- 1968: Douglas Engelbart, Director of the Augmentation Research Center at SRI, is inspired by Bush's article. He realizes that the concept can be achieved much more readily using digital computers instead of an electromechanical system. In 1968 he demonstrates their oNLine System (NLS) in what we now call the "Mother of all Demos" including a mouse, graphical user interface, collaborative word processing, teleconferencing and a host of other features that would take decades to make it into the mainstream.
- 1973: Alan Kay, who had attended Engelbart's demo, incorporates many of Engelbart's ideas into the Xerox Alto. Designing the Alto so that it can be used by children, Kay's insight is that the user interface should manifest the functions that are available. Thus, the system itself can teach the individual how to use it.
- 1984: Steve Jobs, who had seen a demo of the Alto in 1979, incorporates key elements into the Apple Macintosh. Features inherited from NLS and the Alto include the mouse, GUI and computer networking. Jobs' most important contribution is to get these ideas out of the lab and offer them to a mass market.
But there was a critical feature in NLS that we have not yet replicated. Each document was given a unique ID. Printed NLS documents were easily recognized because they included index numbers in the margins. The document ID and index number allowed individuals to reference any line in any NLS document.
That need for consistent identifiers that can be referenced has yet to be addressed for most texts. Today, the best that citation systems can do is refer to a page number. But page numbers change with different formats (e.g. hardbound vs. paperback) and editions. Suppose, for example, you want to cite a particular quote from Huckleberry Finn. In order to do so, you have to specify the publisher and edition of the book before citing the page number. And the odds of a reader having that same edition is pretty low. Textbook publishers have taken advantage of this. By changing pagination between editions, they deliberately obsolete previous editions.
With the advent of digital books the problem is compounded. Page numbers change according to user preferences like font size and page orientation. As a stopgap, the Amazon Kindle added "real page numbers" so that you can use references derived from the paper version of a book. But the problem of persistently valid references across editions lingers.
As we honor the legacy of Doug Engelbart, it's appropriate to consider one more of his innovations -- a persistent and universal referencing system. We still need it.