Dynabook

The original Dynabook was to be a book-sized electronic slate computer that a child could carry with them. The child would communicate with the slate using an object-oriented programming language and manipulate objects using a pen. Alan Kay developed this concept while he was working on the Smalltalk language and later created Squeak to implement Dynabook concepts on regular PCs.

More in Wikipedia: http://en.wikipedia.org/wiki/Dynabook