Quadtree Software provided physical models for microprocessors. The models were ‘certified,’ which means that the device manufacturer of the corresponding model has agreed to full testing and certifying as to the accuracy of the model. Most models were simply ‘validated,’ which means that appropriate test vectors are developed to expertly validate functional and timing characteristics of a device. These models are then compared to the actual device using a hardware modeler. Validated models tended to be extremely accurate physical models, representing the state-of-the art in behavioral-model testing.
