This paper explains the design and the construction of the prototype of an end-ladder card for the silicon drift detector of a high-energy physics experiment at CERN. The end-ladder performs data reduction, compression, and packing for a data acquisition chain. In particular, the end-ladder card includes a chip whose main function is to execute these tasks. Besides the chip's functions, the end-ladder card interfaces with the front-end electronics and processes and transmits the data set

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... d from the front end through an optical channel to the counting room. The paper also describes this chip and the ongoing tests on its production. In addition, the paper shows details of the end-ladder prototype card's design and of the relative tests that are going to be carried out in the near future. Index Terms-ALICE, CARLOS, end-ladder, rad-hard.