from
The Free On-line Dictionary of Computing (8 July 2008)
Uninterruptible Power Supply
<hardware> (UPS) A battery powered {power supply unit} that is
guaranteed to provide power to a computer in the event of
interruptions in the incoming mains 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)