How do I compare waveforms from multiple simulations in QuestaSim/ModelSim
You need to save two waveforms/datasets as .wlf files.  See 'Saving a Simulation to a WLF file' in the QuestaSim manual.  Then you can compare those separate datasets by going under Tools &gt; Waveform Compare &gt; Start Comparison.  Also, see 'Waveform Compare' in the QuestaSim manual.  It is pretty straight forward.