4.2 Design Rule Check

The first step in the fitting process is a Design Rule Check. During this stage, the fitter checks for illegal pin assignments, such as assigning an output to a dedicated input pin. It also checks whether the design exceeds device limitations, including the number of product terms and registers being used and total number of buried resources needed. If the design uses more resources than are available in the ATF1500 or ATF15XX devices, the fitter fails the Design Rule Check and reports an error. In addition to validating the device resources, the Design Rule Check removes all unused signals from the design.