Is it possible to build a useful personal computer that has no operating system, no user applications, not even a mouse (or some other pointing device)? It is! Jef Raskin explains this radical approach to computer design in The Humane Interface: New Directions for Designing Interactive Systems. He demonstrated that this idea is both practical and commercially viable by building the Canon Cat. Tests proved that users were more productive on this new computer than they were on traditionally designed systems.

PS: Another interesting fact about the Canon Cat: Its entire software system was developed in Forth, another masterpiece of great design!