Toward a general simulation capability

Simulation of a system by digital computer requires: • A model of the system which is intelligible to the student of the system while compatible with the limitations of the computer. • Translation of the model to computer code. • Movement of the model through time. • Recording the performance of the model. SIMPAC, a "simulation package," incorporates coherent techniques and devices for the accomplishment of these objectives: modeling concepts for building a computer-compatible model, a vocabulary for encoding the model, a computer program for moving the model through time and recording its performance, and an output presentation program. A model of a hypothetical business system has been implemented with the first version of SIMPAC for the purpose of studying management controls in a complex system. This paper discusses digital simulation and SIMPAC and introduces modeling concepts which may lead to a set of simulation systems, called 'Muse', which would assemble models of varying complexity from descriptive statements and analyze the models prior to simulation.