The air data computer (ADC) is an additional and improved means of supplying the pilot and co-pilot with airspeed, altitude, vertical speed and mach number. Previously, air pressure was supplied to the primary pitot/static flight instruments by long lengths of P/S pipelines. To minimize these, a central unit was developed where the pitot and static pressures could be fed. This unit is known as ‘The Centralized Air Data Computer’. The outputs from the CADC are in the form of synchro signals therefore, the CADC may be referred to as being an analogue device. These are still widely used, although later generation aircraft have switched to digital units.
The simple pitot static system is still fitted in almost all aircraft and will be used as a safety/comparison factor against the CADC and vice versa. Two independent CADC systems would be installed, the input to each would be from independent sources for safety reasons.
A modular arrangement is shown along with a typical transmission system. 
