Abstraction and extensibility in digital logic simulation software

Students of Computer Organization should be able to "learn by doing" at all levels of computer design. Digital logic circuitry is frequently taught using simulation software, however such platforms are often limited to exposing only a narrow range of design levels. This paper describes how, in the new multilevel simulation system DLSim 3, we are able to incorporate abstraction and extensibility to present the many levels of complex circuit designs in a single environment: from low level combinational and sequential circuits, through models of complete CPUs. Among other features, DLSim 3 is able to accomplish this by providing three different types of circuit abstraction: cards, chips, and plug-ins. Using DLSim 3, students recognize the uniformity of system structure, as well as the principles of abstraction that link the various levels of design.