Invented in 1971, the microprocessor evolved from the inventions of the transistor (1947) and the integrated circuit (1958). Essentially a computer on a chip, it is the most advanced application of the transistor. The influence of the microprocessor today is well known, but in 1971 the effect the microprocessor would have on everyday life was a vision beyond even those who created it. This paper presents the history of the microprocessor in the context of the technology and applications that drove its continued advancements.