Inside simulation software: how it works and why it matters

This paper provides beginning and intermediate simulation practitioners and interested simulation consumers with a grounding in how discrete-event simulation software works. Topics include discrete-event systems and modeling; entities and resources; simulation runs; entity states; entity lists; and list management. The implementation of these generic ideas in SIMAN, ProModel, and GPSS/H is described. The paper concludes with several examples of "why it matters" for modelers to know in fine detail how their simulation software works.