You'd need something like a 'stop' state, distinct from reset. The system power supply would have to release the STOP line to allow the computer to continue pro

You'd need something like a 'stop' state, distinct from reset. The system power supply would have to release the STOP line to allow the computer to continue processing, and the power supply would also have to assert STOP on event of the power sagging below specified levels. Whether the power dropping is due to a user intentionally hitting a power switch, or the grid dropping out would be immaterial. 'STOP' simply prevents the computer from attempting to process when low voltage would cause unreliable logic. You'd still want RESET because from time to time you want the ability to put the system into a known state.