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I know computers and other eortcelnics continue to keep track of time when powered off with a small battery. What I want to know is what does a computer do to keep track of 19:30:48 What does it use as a reference for a second, or an hour? What I'm trying to ask is, how does a computer know when one second has passed?My question was how does it know a nanosecond has passed. I understand a computer lacks a concept of time or consciousness. All I wanted to know was how a computer knows that time has passed. In a mechanical clock, it's designed so that the second hand moves at a rate of one second, and that turns gears so the minute hand moves, then that turns the hour hand. What is the electronic equivalent of this?