The device thtat controls the Stargate, more comonly known as the DHD. The dial-home device, constructed by the Ancients, has 38 of the 39 symbols on its Stargate (minus the point of origin), allowing the user to "dial" and desired destination. Despite the advanced technology, the device has a limited power supply.
Unlike the dialing computer, the DHD does not require the inner track of the Stargate to unlock spin in order to establish a wormhole. Instead it is capable of "quick dialing," where pressing the seven glyphs on the DHD are all that are needed to open a gateway.
In case of an overload, the master control crystal can be removed and reinstalled. If a pattern was held in the memory buffer without being reintegratedby the recieving gate, this process will allow the person or item to complete the reintegration process. Periodically, the DHD initiates a correlative update program, in which it automatically dialls several nearby Stargates and transmits to their DHDs revised coordinate data, in order to compensate for stellar drift and to maintain the uniformity of the system software.
In the Pegasus Galaxy, not all Stargates require a DHD to operate: Space-based gates, are powered instead by three power nodes, and dialing is accessed by a panel on a ship. DHDs on planets there, however, are very similar, but with a blue button in the center.
Stargate Technology Index