Abstract: A processing system includes a scheduling system to scheduling processing of lots which are distributed among various processing system stations. Process scheduling is determined in accordance with lot specific composite ratios which are a function of process scheduling factors. Such process scheduling factors include, for example, a processing system efficiency, customer factors, and market factors. Processing system efficiency is influenced by a hunger ratio which is a ratio of the time when a particular lot is needed by a next constraint resource in the lot's process flow and the planned cycle time of a select lot to such next constraint resource. Customer factors include a critical ratio of the lateness of a lot relative to the lot's due date, and market factors reflect the relevant market priority of the lot. The process scheduling factors may be weighted to control their influence on the composite ratio.