The EDRO board connected to the Associative Memory: a "Baby" FastTracKer processor for the ATLAS experiment

The FastTracKer (FTK), a hardware dedicated processor, performs fast and precise online full track reconstruction at the ATLAS experiment, within an average latency of few dozens of microseconds. \ It is made of two pipelined processors, the Associative Memory finding low precision tracks, and the Track Fitter refining the track quality with high precision fits. FTK has to face the Large Hadron Collider (LHC) Phase I luminosity. So, while the new processor requires the best of the available technology for tracking in high occupancy conditions, we want to use already existing prototypes to exercise soon the FTK functions in the new ATLAS environment. Few boards connected together constitute a "baby FTK" that will grow soon becoming the "vertical slice".\ The vertical slice will cover a small projective wedge in the detector, but it will be functionally complete. It will provide a full test of the entire FTK data chain, in the laboratory first and on beam-on conditions after. It will require early development and testing of the software needed for full operation of FTK within the ATLAS TDAQ environment. It will allow to test in beam-on conditions the new FTK prototypes produced for the high luminosity. They will gradually substitute the previous generation of boards. Installation and testing of the vertical slice components with beam will be truly parasitic until the tests will be complete. When the studies in parasitic mode will be complete, the vertical slice could grow again and become a small demonstrator to take data before the long shutdown and to show the FTK impact on Atlas selected physics channels, before the full production. We report on the performances and structure of the baby FTK, the first nucleus of the vertical slice, including the pixel/strip hit clustering (clustering mezzanine), hit organization and distribution (EDRO) and the Associative Memory pattern recognition function. We describe briefly also the possible future evolution including the addition of the Track Fitter.