The EMU connector has five pins for USB on one side. While regular USB connectors are empty on the other side, EMU has more pins intended for headsets. In HTC's version, two pins are for the microphone, three are for stereo sound, and one is for the push-to-talk switch.
The EMU connector features five USB pins on one side, while regular USB connectors lack any pins on the opposite side. For headsets, EMU has extra pins: two for the microphone, three for stereo sound, and one for a push-to-talk switch. In HTC's version, these functionalities are incorporated.