Use of fast processors for on line triggering and event filtering

Within the framework of SPS experiments the authors have inserted one or more bit slice microprocessors to obtain an improvement of data quality and time efficiency and more flexibility in adapting to experimental conditions. For experiment WA2 (1976-1978), analysis by microprograms of ADC data, MWPC and TDC multiplicities, and TDC data formatting has made it possible to reject 70% of events. This in turn allows an efficient online control and savings of approximately=100 h of CDC CPU time. In experiment NA10 (1980-1981), physics requires an increase in beam intensity by a factor of 10. Four microprocessors working in parallel allows one to concile to readout data flow with the acquisition capacity of the two computers N 10-N 500 due to a 90% reduction of the data flow. The use of modular units adapting to the different readout systems and to the experiment permits easy integration. A complete development system facilitates the updating of software. (0 refs).