The Master Command Unit, also known as a master-control unit or master control unit, was a small box-like component with multiple switches usually worn at the belt. It handled many minor programs such as lighting, portals, and commo. The unit could also network more advanced systems like primary defense and security systems. The master-control unit itself was not self-contained and needed ancillary equipment to link the small unit to its primary control circuitry. Before its destruction around 2 BBY, the ancillary system at Stars' End had receptor circuitry built into the walls of the tower, always in close proximity to the master-control unit that Viceprex Hirken carried.