What feature might a dual-trace oscilloscope have?

A dual-trace oscilloscope is designed to display two signals simultaneously, which enhances the ability to analyze comparative waveforms. One notable feature it might have is a Z input for intensity modulation. This feature allows the user to control the brightness or intensity of the displayed waveforms on the screen based on the signals being monitored. By using this Z axis input, the oscilloscope can highlight one trace over another, effectively making it easier to distinguish between two overlapping signals or to emphasize changes in one signal relative to another.

In the context of the other options, while digital signal processing enhances the capabilities of some oscilloscopes, it is not specifically a characteristic unique to dual-trace oscilloscopes. External triggering capability is common in many types of oscilloscopes but does not specifically define dual-trace functionality. Lastly, the analog storage function pertains more to storage oscilloscopes that can capture and hold waveforms for later analysis, rather than being a distinct feature of a dual-trace oscilloscope.