When running a Timing Simulation of a 5K device in Foundation 1.4 the outputs of the simulation are undefined.
解决方案
The cause of this may be that the registers are not getting initialized properly. There is a signal called GR in the simulation netlist which simulates the power-on global reset. This GR signal must be toggled at the start of the simulation in order to properly initialize the simulation.
To drive this GR signal: Select Signal -- Add Signals. Then double click on the GR signal. Now apply a stimulas to the signal and Toggle. Hold it high for a clock cycle at least ( This resets the Flip Flops ), then hold it low for the rest of the simulation.