FIRST COME, FIRST SERVED CAN BE UNSTABLE

We consider flexible manufacturing systems using the 'first come, firs t served' (FCFS or FIFO) scheduling policy at each machine. We describ e and discuss in some detail simple deterministic examples which have adequate capacity but which, under FCFS, can exhibit instability; unbo undedly growing WIP taking the form of a repealed pattern of behavior with the repetitions on an increasing scale.