> "Today's multimedia machine makes the computer screen into a
demanding focus of attention rather than allowing it to fade into the background.<p>> Perhaps most diametrically opposed to our vision is the notion of "virtual reality," which attempts to make a
world inside the computer.<p>Some interesting implications for the "attention economy" here. Companies that sell advertising aren't going to want to fade into the background. And indeed one of the biggest, Facebook, is working on VR for this.<p>> My colleague Roy Want has designed a tab incorporating a small display that can serve simultaneously as an
active badge, calendar and diary. It will also act as an extension to computer screens: instead of shrinking a
program window down to a small icon on the screen, for example, a user will be able to shrink the window onto
a tab display<p>More or less a direct mapping to the smartphone and smartwatch.<p>> The next step up in size is the pad, something of a cross between a sheet of paper and current laptop and palmtop
computers. Bob Krivacic at PARC has built a prototype pad that uses two microprocessors, a workstation-sized
display, a multi-button stylus, and a radio network that can potentially handle hundreds of devices per person
per room<p>.. and this is the modern tablet. (In 1991 "workstation sized" displays could well have still been 14"; we've now converged on laptops being about 13" as well as the iPad Pro)<p>> One way to think of pads is as an antidote to windows<p>.. and indeed tablets started out without windows, and generally don't support more than one window even now.<p>> Boards built by Richard Bruce and Scott Elrod at PARC currently measure about 40 by 60 inches and display
1024x768 black-and-white pixels.<p>Ah, the anti-retina display!<p>> Even today, although active badges and self-writing appointment diaries offer all kinds of convenience, in the
wrong hands their information could be stifling. Not only corporate superiors or underlings, but overzealous
government officials and even marketing firms could make unpleasant use of the same information that makes
invisible computers so convenient<p>Still an unsolved problem.