Baity Jesi, MarcoFernández Pérez, Luis AntonioMartín Mayor, VíctorMuñoz Sudupe, Antonio2023-06-192023-06-192014-020010-465510.1016/j.cpc.2013.10.019https://hdl.handle.net/20.500.14352/35157© 2013 Elsevier B.V. Artículo firmado por 24 autores. We warmly acknowledge the excellent work done by the Janus II team at Link Engineering. In particular we thank Pietro Lazzeri, Pamela Pedrini, Roberto Preatoni, Luigi Trombetta and Alessandro Zambardi for their professional and enthusiastic work. The Janus II project was supported by the European Regional Development Fund (ERDF/2007-2013, FEDER project UNZA08-4E-020); by the European Research Council under the European Union’s Seventh Framework Programme (FP7/2007-2013, ERC grant agreement no. 247328); by the MICINN (Spain) (contracts FIS2012-35719-C02, FIS2010-16587); by Junta de Extremadura (contract GR101583); by the Italian Ministry of Education and Research (PRIN Grant 2010HXAW77 007).This paper describes the architecture, the development and the implementation of Janus II, a new generation application-driven number cruncher optimized for Monte Carlo simulations of spin systems (mainly spin glasses). This domain of computational physics is a recognized grand challenge of high-performance computing: the resources necessary to study in detail theoretical models that can make contact with experimental data are by far beyond those available using commodity computer systems. On the other hand, several specific features of the associated algorithms suggest that unconventional computer architectures – that can be implemented with available electronics technologies – may lead to order of magnitude increases in performance, reducing to acceptable values on human scales the time needed to carry out simulation campaigns that would take centuries on commercially available machines. Janus II is one such machine, recently developed and commissioned, that builds upon and improves on the successful JANUS machine, which has been used for physics since 2008 and is still in operation today. This paper describes in detail the motivations behind the project, the computational requirements, the architecture and the implementation of this new machine and compares its expected performances with those of currently available commercial systems.engjournal articlehttp://doi.org/10.1016/j.cpc.2013.10.019http://www.sciencedirect.com/open access53Special-purpose computerMonte-Carlo simulationsGlass modelsIsing-modelDynamicIanus.Física (Física)Física-Modelos matemáticos22 Física