Also checkout his book The Humane Interface ( https://en.m.wikipedia.org/wiki/The_Humane_Interface https://en.m.wikipedia.org/wiki/The_Humane_Interface ) he wri

Also checkout his book The Humane Interface ( https://en.m.wikipedia.org/wiki/The_Humane_Interface https://en.m.wikipedia.org/wiki/The_Humane_Interface ) he writes a little about this system there while describing the ideal interface in his mind.