Abstract : By its very design, ACSL is intended for computer simulation of continuous or continuous/discrete systems. Numerical integration methods are built-in, and provision is made for all of the interacting physical processes that normally take place in parallel between integration steps. A well-written ACSL program is inherently modular, making subsequent use by other programmers much easier. ACSL also has provision for parametric studies, which are often required in simulations, as well as support for various plots, including time response, gain, phase, Nichols, and Nyquist plots.