Modeling and simulation tool for automatic control systems in the time and frequency domain based on the idea of block diagrams. Full visual block diagram editor for comfortable system modeling. The frequency simulation lets build Bode and Nyquist plots and computes the eigenvalues of the evaluated system or subsystems. The time simulation shows the system response as time and x/y plots. All results (plots and data tables may be copied to other applications by means of the Windows clipboard). The tool palette contains more than 90 basic function blocks in 11 categories (sources, linear, nonlinear, graphs, actuators, controllers, time discrete, converters, logic, miscellaneous and special). Users can make extensions by creating and using custom blocks. The parameter variation feature lets compare system responses with varying parameters having up to 99 distinct values. Additional drawing capabilities let you illustrate your models with various shapes and text.