The ATLAS Fast Tracker Processing Units - input and output data preparation

The ATLAS Fast TracKer(FTK) is a custom hardware system for fast, associative memory based track reconstruction. It will provide tracking information within the full acceptance of the inner tracking detectors to the high level trigger at a rate of up to 100 kHz. %, thus allowing for a refined and more efficient event selection at the trigger level. At the first stage of the FTK the Data Formatter subsystem clusters inner detector hits and organizes them into 64 $\eta$-$\phi$ trigger regions. At the last stage, the FTK to Level-2 Interface Cards repackage track records and send them to the high level trigger computing farm. This report aims to give an overview over the functionality of the two systems, their hardware implementation in the Advanced Telecommunications Computing Architecture standard, and the status of their integration into ATLAS.