Of course 2001 is not the only science fiction to feature tablet computers. In 1996 I gave a talk to the Australian Computer Society in which I suggested that by 2005, the Personal Access Display Devices (PADDs) of Star Trek Next Generation would become commonplace:
"... the dimensions of a B5 sheet of paper, by 1 cm thick). PADDs usually have a touch sensitive screen covering the whole upper surface, which is also a high resolution (2000 x 2000 pixel by 16 million colour) screen. All PADDs have video and audio built in and can operate as what a 1996 person would know as a mobile phone, radio, TV and video cam-corder. ...Senator Helen Coonan, Australian Minister for Communications, Information Technology and the Arts, refereed to this talk in the speech "Developing a National ICT Capability" in 2007.
Variations on pen based writing and voice input were tried for PADDs, but it was found that just a finger pressing buttons displayed on a touch sensitive screen were enough. Most people's writing wasn't good enough for pen input (and they usually just need to select from a few menu options anyway). Voice input works well, but was disruptive in a group and people were too self conscious to talk to a lump of plastic on their own. The QWERTY keyboard, in its virtual form is still in use for data entry. ..."
From: "Australia: The Networked Nation",Tom Worthington, Draft of: 4 February 1996, delivered, 7 February 1996 in the Audio/visual room of the Townsville Grammar School. Republished as the chapter "The Networked Nation", in the book "Net Traveller", 21 July 1999