A severely scaled information processor

Like energy, the term information is both self-evident and abstract. The chapter begins by outlining the formal Shannon definition of the measure of information and provides several illustrations from language, materials systems, and the living cell. For example, it is estimated that an Escherichia coli cell during its 40-minute reproduction process must generate about 10 11 output bits. Then given the measure of information, an elementary general-purpose information processor is defined and used as a vehicle from which to estimate its overall performance based on the limiting transistor/interconnect parameters developed previously in Chapters 2 and 4 2 4 . In particular, it is shown that it is possible to determine such parameters as instruction cycle time, processor area, power/energy, and information output rate. It turns out that especially for the 1-μm-sized system, physical limits on the achievable removal of heat drive the need to operate at a lower clock speed. The heat removal challenge is not so severe for the 10-μm-sized system because of larger surface areas through which to transfer heat.