In conventional aircraft, mechanical linkages and cables connect pilot controls, such as the rudder pedals and stick, to hydraulic actuators at the control surfaces.
All connections are electrical and are routed through computers.
Software can be adjusted to suit increasingly complex and varied payloads. Subsystems, like the main engines, that had no computer assistance before use them for performance improvement. And, as in Gemini and Apollo, guidance and navigation tasks are accomplished on the Shuttle with computers. These digital devices were combined into a coherent system, rather than isolated in function and location within the aircraft. Several modem military airplanes have applied this concept to varying degrees.