process control simulator contains electronic circuits for modifying set-point control signals by summing, integrating, differentiating and introducing step functions on continuous, single or periodic bases to determine off-line the behaviour of a process control system [6]. Provisions are made for several interacting control loops, for dead-time delays and for faster than actual response times to speed up simulation. The dead-time delays are provided by scanning a set of storage capacitors with a variable speed scanning motor through a scanning control cycle of operation. A three control loop controller section provides for setting the gain of the controller system and controlling integration and difference modes responsive to step disturbances introduced into an integration process after a selectable dead-time adjustment. The output signal is reproduced in the form of a process response waveform.