  An extension of non-deterministic processes driven by the random telegraph
signal is introduced in the framework of "piecewise deterministic Markov
processes" [Davis], including a broader category of random systems. The
corresponding Liouville-Master Equation is established and the upwind method is
applied to numerical calculation of the distribution function. The convergence
of the numerical solution is proved under an appropriate
Courant-Friedrichs-Lewy condition. The same condition preserve the
non-decreasing property of the calculated distribution function. Some numerical
tests are presented.
