Abstract: An adjustable incremental load simulator 200 acts upon a telephone control processor 300 to drive the processor toward and into an overload state. This is accomplished by reducing the number of processing cycles available for system task execution by execution control 360. The simulator 200 pulses an interrupt circuit 350, thereby halting the execution of system tasks for a fixed number of processing cycles. The adjustable incremental load simulator has an adjustment which controls the rate of generation of interrupt signals and thereby controls the rate at which system task execution cycles are made unavailable to the execution control. The performance of the system is monitored via a display 150; thus, the simulated incremental load can be adjusted while system performance is monitored.