On startup, it defaults to the first memory slot and doesn’t supply any power to the outputs. The output is enabled and disabled by the output switch. There are five memory slots, with the first four being accessed by pressing a corresponding hardware button labelled M1–M4. The fifth memory slot is only accessible by first selecting the M4 memory slot and then turning the dial to switch to M5. When any change is made in any memory slot, it’s automatically saved. Switching between any memory slot automatically turns off the output, so you can’t accidentally fry something by switching to a different supply. We found this a great unit to use and it has some nice features for its price point. However, better instructions and including a few leads in the box would be nice additions. Apart from the power ON/OFF switch theTenma T210480 comes with the output cut off. You don’t have to turn off the power supply to stop the power. Over Voltage/Current Protectionis nice to have. You don’t get that on all budget models. Speaking about the current, dial shows the current draw and the voltage drop. Lastly, the digital rotary potentiometer (read: the big white knob) is great. It comes with the digit selection keys for fine tuning. You can either select what digit you want to modify or keep adjusting the value by turning the knob left and right. If you want to go down from 3.3V to 5V you can either select the correct number row or keep increasing the values at defined increments.