The Associative Memory Serial Link Processor of the ATLAS Fast TracKer Processing System

The upgrade to the Trigger and Data Acquisition (TDAQ) system of the ATLAS experiment at the LHC will improve the capability of the detector to select the events with the greatest scientific potential. The Fast TracKer (FTK) is one of the ATLAS TDAQ upgrades that is presently under commissioning. FTK is a custom hardware system that provides the High Level Trigger (HLT) with charged particle tracks reconstructed from hits in silicon detectors at the rate of 10⁵ events per second. The main processing element of FTK is the Associative Memory (AM) system that is used to perform pattern matching with a high degree of parallelism. Its implementation is called the AM Board Serial Link Processor (AMBSLP) and it is a very efficient pattern matching machine that handles in parallel massive data samples. The AMBSLP consists of two types of boards: the Little Associative Memory Board (LAMB), a mezzanine where the AM chips are mounted, and the Associative Memory Board (AMB), a 9U VME motherboard that hosts four LAMB daughter-boards. We report on the complex FPGA firmware design that has been implemented to operate the high degree of parallelism of the board. We also report on the commissioning status of the AMBSLP and on the performance of the Processor during early data taking.