When the radio is turned off and there is a battery in the unit along with the AA batteries, which batteries are keeping the memory presets and clock set?

The presets and clock are maintained by the NICAD battery when the radio is turned off. When the NICAD battery is not in the unit the AA batteries act as a back up and keep the memory presets and clock. When the radio is plugged in and turned off the AC power maintains the clock and presets.