Data Acquisition Systems

We will review the main physics and operational requirements on the Trigger and Data Acquisition (DAQ) systems of the LHC experiments. A description of the architecture of the various systems, the motivation of each alternative and the conceptual design of each filtering stage will be discussed. We will then turn to a description of the major elements of the three distinct sub-systems, namely the Level-1 trigger, the DAQ with its event-building and overall control and monitor, and finally the High-Level trigger system and the online processor farms. The thrust of the two lectures will be to provide a "broad brush" picture of the functionality of these systems.