Uninterruptible Power Supply(UPS) A battery powered power supply that is guaranteed to provide power to a computer in the event of interruptions in the incoming electrical power. Different rating UPSs will provide power for different lengths of time. Modern UPSs connect to the computer's {serial port} and provide information such as battery time remaining, allowing the computer to shut down {gracefully} before complete loss of power. (1996-12-11)