It's absolutely mindblowing what they built in one year in 1992(!). It had had a touch screen and inertial scrolling.
Also, 1992 was late for touch screens. Plato (http://en.wikipedia.org/wiki/Plato_computer) had one in 1972, and wasn't even the first (http://billbuxton.com/multitouchOverview.html)
So, like almost everything in technology, once you zoom out enough, things that seemed outliers start to fit in patterns.
Invalidating prior art? Well, that's a very different question.