A Priority System with Setup Times

A single server system is considered with 2 classes of customers. Customers of class 1 have preemptive priority over customers of class 2 but the order of service within each class is first-come, first-served. Whenever service is changed from one class to the other an orientation or change-over time is incurred. Arrivals are Poisson, service and orientation times are independent and arbitrarily distributed. Laplace Transforms and expected values of the steady state-waiting time distributions are obtained for each class.