<P> Some electronics simulators integrate a schematic editor, a simulation engine, and on - screen waveform display (see Figure 1), allowing designers to rapidly modify a simulated circuit and see what effect the changes have on the output . They also typically contain extensive model and device libraries . These models typically include IC specific transistor models such as BSIM, generic components such as resistors, capacitors, inductors and transformers, user defined models (such as controlled current and voltage sources, or models in Verilog - A or VHDL - AMS). Printed circuit board (PCB) design requires specific models as well, such as transmission lines for the traces and IBIS models for driving and receiving electronics . </P> <P> While there are strictly analog electronics circuit simulators, popular simulators often include both analog and event - driven digital simulation capabilities, and are known as mixed - mode simulators . This means that any simulation may contain components that are analog, event driven (digital or sampled - data), or a combination of both . An entire mixed signal analysis can be driven from one integrated schematic . All the digital models in mixed - mode simulators provide accurate specification of propagation time and rise / fall time delays . </P> <P> The event driven algorithm provided by mixed - mode simulators is general purpose and supports non-digital types of data . For example, elements can use real or integer values to simulate DSP functions or sampled data filters . Because the event driven algorithm is faster than the standard SPICE matrix solution, simulation time is greatly reduced for circuits that use event driven models in place of analog models . </P> <P> Mixed - mode simulation is handled on three levels; (a) with primitive digital elements that use timing models and the built - in 12 or 16 state digital logic simulator, (b) with subcircuit models that use the actual transistor topology of the integrated circuit, and finally, (c) with In - line Boolean logic expressions . An example of a mixed - mode simulator is shown in Figure 2 . </P>

What is the meaning of simulation in marathi