Computer simulation of computer system performance

As the usage of some computer systems became more specialized and complicated, there became a need to study the performance of the software as well as the hardware. Thus, simulations were developed to assist in the design and in the improvement of the overall performance of these systems. The categories covered by such simulations ranged from batch processing direct couple systems to time-sharing systems to more specific systems such as those for message processing and switching. It is the intent of this paper to examine the circumstances which have led to the existing state of affairs and to illustrate the benefits which appropriate system performance simulations of some of the newer systems could bestow.