Danby Microwave Why/How Does My Microwave Beep Half Hourly When It's Not Plugged In?

Why/How does my microwave beep half hourly when it's not plugged in? - danby microwave

I have a Danby microwave. Nothing special, just a special case, $ 50 Walmart. It works well, but these days I realized that even sound every half hour. I've tried to disconnect and reconnect it to see if they fix it. This has nothing, so I was frustrated and finally completely out. Unfortunately, this is not the problem is solved still solid, although there is no power, it would. Is there some sort of computer inside with a "technical problem"? Its really freakin 'boring.