GPSS

General Purpose Simulation System (GPSS) (originally Gordon's Programmable Simulation System after creator Geoffrey Gordon; the name was changed when it was decided to release it as a product) is a discrete time simulation general-purpose programming language, where a simulation clock advances in discrete steps. A system is modelled as transactions enter the system and are passed from one service (represented by blocs) to another. This is particularly well-suited for problems such as a factory. GPSS is less flexible than simulation languages such as Simula and SIMSCRIPT II.5 but it is easier to use and more popular.