Microprocessors are one of the most important technical phenomena of the end of the 20th century and the beginning of the 21st century. For thirty-five years their computing power and their complexity have increased at sustained rates. Microprocessors are increasingly playing a major role in the modern society. The embedded ones are the most numerous, used for controlling and monitoring machine tools, cars, aircraft, consumer electronics and other equipments. There is a gradually changing on the relationship we have with these devices. It is interesting to show that microprocessor phenomenon is ‘‘market-pull’’ rather than ‘‘technology-push’’. The design of new chips represents a continuous challenge for engineers and technologists. They are striving to give to the market the products it requires, and which are generally planned long time before they actually appear. Monolithic microprocessors are overtaking all kinds of computers. Minicomputer lines started using microprocessors during 1980s; mainframe and Unix lines during the 1990s and super-computers during this decade. In this extraordinary evolution, these devices have used all technical innovations that had been conceived for previous generations of computers. To keep an evolutionary rate of computing power and compatibility at binary code level, completely new execution techniques has been invented as data-flow processors, register renaming, SIMD instructions and VLIW execution technique. Future of these devices is very challenging. The need for more and more computing power is still present and technology will finish by reaching physical limits.