Amigas were designed to run without a battery-backed clock, because the machine would always be turned on when the power was on. Many older machines required a battery in order to keep track of the time and date, even when the machine was turned off. This was because back then, computers would often lose their time and date settings when they were turned off. But since Amigas were designed to always be turned on (due to their lack of a power switch), they didn't need a battery to keep track of the time/date.