sim conceives simulation through three operations:
1- Build simulation vectors.
2- Simulate.
3- Print the result.
Exported functions make it possible to build an internal data-structure, and perform the three operations given above. Simulation vectors may be provided by the user. Using exported functions, it is also possible to generate simulation vectors randomly or reading it from a file. Low level functions are also available that evaluate, for example, a network node using a simulation vector. An example of a simulation vectors file may be generated using the simulate command with random-vectors-generation option, in VIS.
WARNING : In order to improve the speed of simulation, it is assumed that each combinational output function is completely specified, and that each simulation vector specifies a minterm over the combinational inputs this assumption is not checked. Incorrect results may be produced if this assumption is violated.