The thesis can be read in two ways, either as a theoretical analysis of the patterns of technical change in modern economies with an illustrative case study on the semiconductor industry, or, conversely, as a reconstruction of the history of that industry, which is at the core of the microelectronics revolution, backed by detailed and unorthodox theoretical premises. A general theoretical task is the explanation of the determinants, procedures and directions of technical change, and its effects on industrial performance and structural change. Despite powerful economic inducements, technology maintains rules and a momentum of its own which binds the direction of technological developments. There are, it is suggested, technological paradigms which define clusters of technological trajectories of progress. Scientific advances together with various institutional factors contribute to determine the timing and the nature of new paradigms, while markets perform as important selection environments. Innovative activities show varying degrees of private appropriability and determine the pattern of lags and leads between firms. Technological asymmetries between firms play a paramount role in explaining industrial performance, including prices, margins, profit rates. The assumptions of traditional industrial economics have to be reversed: instead of starting from an assumption of identity between all firms and then introduce, by complication, oligopolies, one should begin from the opposite assumption. Technical change makes every firm different: a "competitive environment" is that particular case whereby the forces of technological diffusion are powerful enough to wither away innovation-based asymmetries. The thesis undertakes an analysis of the effects of technical change on the patterns of transformation of industries, which in many ways can be considered an exploration into the microfoundations of economic dynamics. The case of the semiconductor industry is not only an illustration of the hypotheses and the methodology, but has a deep interest in its own right. The analysis of the process of birth of the specific semiconductor paradigm, with the contextual impact of American military and space policies, helps in explaining the American technological leadership. Innovation-based competition,cumulativeness of technological advantages, learning by doing, "technology-gap" patterns of trade and investment are factors which reproduced through time the American leadership over Europe. A different case is Japan; there - the thesis shows - important institutional and policy factors fostered a very rapid catching-up process ultimately leading to a joint Japanese-American leadersbi. P in the world semiconductor oligopoly which has been forming throughoutthe sevantics and early eighties. The semiconductor industry is the main engine of transformation of all the industries influenced by microelectronics. Its impact on the user sectors is not confined to ever-improving components at rapidly falling prices, but provides also (and is affected by)a set of untraded technological interdependences, stimuli, information flows, etc, which shapes the overall pattern of transformation of the electronics industry.