Originally Posted by
Maninthebar
In the event that MCAS (or another system) is active the design is that trim signal from the yoke switches overrides* the system-derived input. The decision on which takes priority must be 'processed'. Ergo SOME processing power is involved and a processor, somewhere, is in line.
* I have used the word 'override' but I think 'cancel' might be better in the case of MCAS, or even postpone!
A simple relay (well, simple in an aviation context) is all that it takes to remove MCAS from the trim circuit to allow the main electric trim to override and function normally. There was a circuit diagram of the trim logic posted on one of these threads, and I could probably dig one up with a little time if you really need to see it. Again, a reminder that all manner of complex tasks used to be managed in aviation systems before the advent of IC processors.
That being said, the 5-second pause that MCAS is supposed to take after a main electric trim input is likely incorporated in the circuit logic (which resides within the Flight Control Computer or FCC), so it is possible that this aspect of the MCAS side of the system may be affected by processor issues.