He dragged the schematic into Proteus. The virtual board materialized: the MCU, a regulator, oscillator, the same onboard USB connector. He connected his firmware image and hit Run. The simulator hummed; nets lit up; logic analyzers plotted invisible conversations. At first nothing dramatic happened. Then the simulated power rail dipped for a microsecond during peripheral enable—exactly where the scope on his bench had spiked. The exclusive model showed an internal startup current surge when certain peripherals were enabled before the clock stabilised, a quirk absent from the generic models.