Prescient visions of today's computing go back much farther than that, to the research of Alan Kay and others at PARC. I don't have the materials in front of me but my summary from memory is that they proposed the existence of small computers you would have with you at all times, which could access wireless networks. The small computers would use that access to retrieve information for their user, and to report location to an environment that would respond. It's not too far from what we have with smart phones now. And Alan Kay in particular conceived of a tablet computer very similar to the tablets we have today. I believe all this work was done in the 1970s and 1980s.
Yes, the dynabook concept was created by Kay in 1968. He claimed that the idea hit him when he was in a lecture by Gordon Moore explainig his law...you know the one...
Anyway, knowing something about exponentials he did some quick calculations and voilà, iPad, er, Dynabook.
Also, the Alto "PCs" that Xerox built during the 70ies, the ones with the bitmap display, mouse and Ethernet networking, were known as "Interim Dynabooks", so very consciously and deliberately approximations of the tablet computers to come.
