An update of the 2x2 implementation for the level 0 calorimeter triggers

1. Introduction The 2x2 implementation for the Level 0 calorimetric triggers is described in Refs. [1, 2]. The purpose of this note is to present a detailed description of the data-flow and hardware implementation in answer to the questions of the Trigger Coordinator Hans Dijkstra. System issues are also addressed, such as the synchronisation of signals from the various detectors, the treatment of a ''loss of clock'' condition and aspects relating to the monitoring and debugging of the functioning of the trigger. We also provide details of cost estimates and the total latency of the trigger. Finally the principal milestones for reaching a final design are given in order to meet the deadline for the Technical Design Report (TDR) by the end of 2001. 2. Front-end Electronics and Detector Geometry In this section we present the current status of the front-end electronics for the subdetectors involved in the calorimetric triggers, as well as their geometry, i.e. dimension and pad size. These parameters are only relevant to the trigger implementation because they play a role in the data-flow and hardware implementation.