In this paper we consider a single server queueing model for a single machine dynamic job shop in which shop level scheduling is not permitted. External arrivals of jobs are received in a dispatch area from which their release to the job shop is controlled. To overcome the limitation of operational control, we propose three different dispatch policies and compare their performances to that of a first come first served dispatch policy. The four dispatch policies considered are (1) first come first served, (2) scheduling within generations, (3) scheduling within periodic review, and (4) scheduling within fixed batch sizes.