1. A computerized system for generating user-configured designs of integrated circuits, comprising: a user interface adapted to provide and receive information to and from a user, respectively; and an object-oriented design environment operatively coupled to said user interface and having a plurality of associated design tools, wherein a plurality of components associated with said designs of integrated circuits are represented as objects, at least a portion of said objects being encapsulated and containing information relating to both the interface and build hierarchy associated with its respective design component, said design tools using said information within said objects to build said design, said objects being user-configurable and selectable within said environment via said user interface; wherein said objects being user configurable comprises adding an extension instruction to said designs of integrated circuits, said extension instruction comprising a mixed length instruction set architecture that utilizes instructions of at least two lengths without a mode switch.