1. A processing apparatus comprising: a cassette rest unit configured to place thereon a cassette with a plurality of wafers housed therein; an unloading unit configured to unload a wafer from the cassette placed on said cassette rest unit; a feed unit configured to feed the wafer unloaded from the cassette by said unloading unit; a plurality of processing units disposed adjacent to said feed unit and configured to perform respective different processing processes on the wafer; and a control unit configured to control said cassette rest unit, said unloading unit, said feed unit, and said processing units; wherein the layout of said cassette rest unit, said unloading unit, said feed unit, and said processing units can be changed; said control unit includes a display panel for displaying an input screen for entering operating conditions for the units and memory means for storing at least the operating conditions for the units, wherein said memory means includes an operating condition memory for storing operating conditions for a series of units configured to process a wafer in the processing apparatus, and wherein said control unit includes calculating means for at least calculating a total wafer processing time in a current layout of the overall apparatus map on the basis of at least information on the processing of the wafer on the units and information on the operating conditions; said memory means includes an image memory for preparing in advance and storing respective plan-view images of the units; said display panel displays an overall apparatus map representing a combination of the plan-view images of the units as a layout of the processing apparatus in its entirety; and the layout of the plan-view images of the units in said overall apparatus map can be changed.