CONTROL-ID is a Computer Aided Control Engineering (CACE) tool serving as a support environment for CACSD in the chemical process industry. The fundamental basis for this tool is the theory of control-relevant system identification, which takes advantage of the interplay between identification and control design. CONTROL-ID is implemented using MATLAB on a VAXStation 4000 cluster, which is integrated in real-time to an industrial-scale Honeywell TDC 3000 plant information and control system. Control action is computed on the TDC 3000 system using low-order difference equations, which yield superior performance over traditional PID control while resembling the behavior of model predictive control systems. Results from a simulation study using a gasoil furnace are reported.