The transformation of sector system in Information and Communications Technology (ICT), a prominent character in sector system, has been paid much attention in innovation theory with rapid change in information technologies and technological environment. In this context, we explore how Sectoral Innovation System (SIS) in ICT has been transformed since 1970 by employing US patent data and Proxy variables which measures the basic elements for SIS and its technological characteristics. By utilizing patent data, it is demonstrated that technological regimes, key links and Schumpeterian patterns of innovation in overall ICT sector have drastically transformed over the last three decades. We also reviewed how changes of knowledge bases and technological characteristics driving forces of dynamics in ICT help heterogeneous agents interact with environmental factors (Industrial structure and institutions), leading to industrial or economic growth and its dynamics in the historical perspective over ICT sector (Telecommunication, Computer and Semiconductor). Consequently, our research shows clearly that Schumpeterian patterns of innovation have shifted from Mark I to Mark II in ICT. Our study also provides a glimpse picture of dynamics patent data.