2. Description of the Computer Program: The basic building blocks for Arena simulation models are called modules. There are two basic modules - flowchart and data modules and they define the process to be simulated. Flowchart modules describe the dynamic processes in the model. There are different kinds of flowchart modules, however for simulation model of M/M/1 queuing system, only three flowchart modules - Create, Process and Dispose are used.

The create module is the birth node for arrival of entities to the model's boundary. In this model, it is named "Customer Enters System." Different aspects of this module such as Time between arrivals, Entity type, Entities per arrival etc can be specified in the Dialog box or alternatively in the create spreadsheet view, which is included in the Appendix. For this model, the inter arrival time is exponentially distributed with mean 2 minutes and the entity type is customer with 1 entity per arrival. The process module which is named "Checkout Counter" here represents the cashier, the service provided, the queue and the entity delay time there. Specific action for this module can be chosen in the logic area. In this particular case, "Size Delay Release" is chosen so that this module takes care of entity's seizing of Resource, the Delay for a time representing the service time and then Release units of the Resource for other entities to seize.

The dispose module "Customer Leaves System" simply represents entities leaving the model boundaries. The logic flow for this model is shown by the following flow chart of these modules:.