The ISIS indicator receives digital data inputs from the following components:
(a) Inertial Reference
Two ARINC 429 high-speed buses provide the ISIS indicator with the optional magnetic heading indication (label 320).
In normal configuration, the parameters displayed on the ISIS indicator come from the ADIRU 1.
When a failure is detected, switching on the ADIRU 3 has to be performed manually through the ATT/HDG selector switch on the SWITCHING panel.