A double-level trigger system has been developed for the KLOE experiment. C
ustom electronics asserts a trigger in a 2 mus decision time. The decision
is based on the combined information of the electromagnetic calorimeter and
the drift chamber. The entire trigger system is continuously monitored, an
d data flowing from the trigger system hal e allowed both an efficient onli
ne monitoring of the detector and an online luminosity measurement. (C) 200
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