SIMORD, an interactive simulation program, was developed for designing and analyzing hierarchical configurations of distributed computers used in process control systems. To achieve an adequate response time under all critical conditions, such systems should be designed from the points of view of their function distribution and the planning of their performance. Performance criteria can be specified in terms of system response time to alarm conditions, and maximum activity rate for each processor during steady-state service. Taking into account these characteristics, different computer configurations can be evaluated and compared through simulation in order to select the best control system for a specified physical-chemical process.