Performance and system flexibility of the CDF hardware event builder

The CDF (Collider Detector Facility) hardware event builder, a flexible system built from a combination of three different 68020-based single width Fastbus modules, is discussed. The system may contain as few as three boards or as many as fifteen, depending on the specific application. Functionally, the boards receive a command to read out the raw event data from a set of Fastbus-based data buffers (´scanners´), reformat the data, and then write the data to a level-three trigger/processing form which will decide to throw the event away or to write it to tape. The data acquisition system at CDF will utilize two nine-board systems, which will allow an event rate of up to 35 Hz into the level three trigger. The authors present detailed performance factors, system and individual board architecture, and possible system configurations.<>