out immediately. Note that the time unit is tool-dependent, here it is seconds (on Windows). If necessary, for example, to run the Simulator connected to a real system, the Simulator can run in real time: if you set a timer with a value of five minutes, it will actually timeout after five minutes. To use real-time simulation, you must change the kernel used in the Organizer Make window, as shown in Figure 8.14. Compile & link Use standard kernel Microsoft RealTimeSimulation Use kernel in directory: Preprocess C file Figure 8.14 Selecting real-time simulation in the Make window Then, if you set a ten-second SDL timer, you will see that the timeout occurs ten seconds after pressing the Go Simulator button. 8.1.9 List of Validator options Most of the important Validator options can be changed using Validator menus, but a few require to type a textual command. To avoid using menus to change settings each time the Validator is invoked, it is handy to put the corresponding textual commands into the Validator startup file, valinit.com. The following sections are presented in the same order as the result of the command show- options. 8.1.9.1 Bit-state options Hash table size: 1000000 bytes: number of bytes in the hash table (1 byte can store 8 states). Must be (in states or bits) 50 or 100 times the number of global system states to minimize the collision risk. Search depth: 100: defines the maximum exploration depth; when reached, the Validator backtracks to explore other transitions, the graph is truncated. Iteration Step: 0: do not use. 8.1.9.2 Exhaustive search option Search depth: 100: defines the maximum exploration depth; when reached, the Validator backtracks to explore other transitions, the graph is truncated. 276 Validation of Communications Systems with SDL 8.1.9.3 Random walk options Search depth: 100: defines the maximum simulation depth; when reached, the random sim- ulation stops, returns to the initial state and begins a new random simulation. Repetitions: 100: number of times the random simulation is re