


A logic block is a basic element of Boolean algebra that can be physically implemented, and which can then serve as a primitive for a computing device (Hillis, 1998). For instance, Hillis presents examples of how such logic blocks as OR, INVERT, and AND can be implemented as mechanical devices built from levers and springs, as hydraulic valves, and as electronic components. Hillis also points out that OR, INVERT, and AND are important primitives in the sense that one can combine these three logic blocks in different circuits in order to compose any of the other logical elements of Boole's (1854/2003) algebra. As a result, any system  including artificial neural networks  that is capable of creating these three basic elements is also capable of performing any logical operation, and can therefore be considered capable of creating a universal computer.
References:
 Boole, G. (2003). The Laws of Thought. Amherst, N.Y.: Prometheus Books. (Originally published in 1854).
 Hillis, W. D. (1998). The Pattern on the Stone . New York: Basic Books.
(Added April 2010)



