The Real Time Computer Complex (RTCC) was the central computing facility for the Gemini and Apollo programs, and contained, during the Apollo program, several IBM System 360 mainframes. These systems were used for simulations, offline data processing, and mission support.
For the mission support role, two identical computers were running simultaneously and fed the same data, yet only one at a time was “primary” and used to feed data displays. The second computer ran as a Dynamic Standby system and could take over the primary role at any point through operator intervention.
Was this “failover” capability ever used during the course of a mission, or in some other time-critical moment?
The only reference I have found so far is near the end of this NASA publication which mentions potentially a failure during Apollo 10, but provides no detail. It also isn’t clear if this capability was used any other times.