Data acquisition for the D0 experiment

We describe the acquisition system for the D0 experiment at Fermilab, focusing primarily on the second level, which is based on a large parallel array of MicroVAX-II's. In this design data flows from the detector readout crates at a maximum rate of 320 Mbytes/sec into dual-port memories associated with one selected processor in which a VAXELIN based program performs the filter analysis of a complete event.