In EFIS, in case of failure in the PFD, where would be PFD shown? In case of failure in the ND, where it would be shown? In case the PFD & ND both fail, where would they be shown?
On the Embraer 170/190-series, the normal display layout is as follows:
There is also a manual reversion switch located near each pilot's outboard knee, which controls what is displayed on the panel:
All images sourced from an Embraer Airplane Operations Manual.