A control interface is a means by which a person operating a particular piece of equipment may instruct the device or system as to what he wants it to do, and the item being controlled may respond. It is possible to combine elements of one or more of each type within an overall control system structure as alternative/"back up" means of accessing the controls.
There are five major types of control interface available to most spacefaring species: physical, audio, touch sensitive, motion sensitive, and neural.
Physical
A duotronic-based control interface
A physical control interface utilizes physical buttons, switches, dials, and levers for data input purposes, and relies on physical indicators such as gages, status lights, and visual screens/monitors for response purposes. Manipulation of a physical control is often accompanied by a visual or audio cue to indicate that the input has been accepted by the interface. A major use for physical controls, even after the introduction of more "advanced" systems is the operation of small equipment requiring only relatively simple commands, such as personal weapons, tricorders, and communicators.
Interfaces of this type were the primary ones utilized by Starfleet (Earth) in the 22nd century, and continued to be the prevalent in the Federation Starfleet well into the late 23rd century.
- Some people, such as Tom Paris, felt that physical control interfaces were superior to other forms of interface, particularly in flight control operations. The belief was that the operator had a better "feel" for the responsiveness of the system.
Audio
Audio control interfaces utilize spoken words or other transmitted sounds as both the primary means of data input and systems response, though response via other means could be requested by the operator. 23rd-century computers made frequent use of audio interfaces, as did personal communicators, a trend which continued into the 24th century.
Touch-sensitive
Touch-sensitive interfaces typically consist of featureless panels with no physical instruments to manipulate at all. The entire surface can be controlled by computer to display a layout of marked areas which serve the same function when the surface detects contact from the user. They are considered more "flexible" than physical interfaces, being capable of being rapidly reconfigured into whatever form a user might require.
The Federation Starfleet began to experiment with touch sensitive interfaces in the mid 2280s by incorporating them into the bridge of the prototype USS Excelsior. (Star Trek III: The Search for Spock)
Motion Sensitive
Motion sensitive interfaces are generally used to control simple mechanisms, such as pocket doors and lights. Some such interfaces could also be found on the bridge of the USS Enterprise in the mid-23rd century. (TOS: "The Cage", "Where No Man Has Gone Before")
- In at least one alternate universe, Starfleet began to use so-called "holographic" control interfaces on board their ships. Little is known about them, but given the 3D nature of a hologram, some sort of motion/position sensitive operating mechanism seems likely. (DS9: "The Visitor")
Neural
Neural interfaces directly transmit commands from and information into the brain of the operator.
In the 23rd century, Commander Spock's brain was stolen by an alien race and connected to a neural interface to coordinate the life support systems of their habitat. A more primitive form of interface was used to maintain and control his body until the brain could be restored to it. (TOS: "Spock's Brain")
Geordi La Forge used a VISOR to compensate for his blindness that contained neural interfaces. He also participated in an experiment using an neural interface controlled remote probe.
Neural interfaces are frequently used in clandestine/criminal activities. (DS9: "Honor Among Thieves")