CDF Trigger Interface Board ´FRED´

We describe FASTBUS boards which interface sixteen different trigger interrupts to the Collider Detector Facility (CDF) data acquisition system. The boards are known to CDF by the acronym \´FRED\´. The data acquisition scheme for CDF allows for up to 16 different parts of the detector, called \´Partitions\´, to run independently. Four partitions are reserved for physics runs and sophisticated calibration and debugging: they use the common Level 1 and Level 2 trigger logic and have access to information from all the components of the CDF detector. These four partitions are called "CDF Partitions". The remaining twelve partitions have no access to the common trigger logic and provide their own Level 1 and Level 2 signals: they are called "Autonomous Partitions". Fred collects and interprets signals from independent parts of the CDF trigger system and delivers Level 1 and Level 2 responses to the Trigger Supervisors (FASTBUS masters which control the data acquisition process in each partition).