AbstractThis paper describes the results of a study of the feasbility and cost- effectiveness of using mixed Prolog/Fortran programming to develop flexible, reconfigurable battle simulations, replacing large Fortran programmes which are difficult to modify. A mixed-system architecture is developed, in which Fortran and Prolog are each used to best advantage, and which allows discrete events to be combined with pseudo-continuous processes. The architecture is analysed in terms of a number of performance metrics. The paper concludes that the mixed architecture is feasible, practicable and brings a variety of benefits.