18 979-8-3503-2014-5/22/$31.00 ©2022 IEEE HRS-100 creation and application history Aleksandr A. Menn Institute of Control Sciences Russian Academy of Sciences Moscow, Russia menn@soyuzmadstyle.ru Božidar L. Radenković Faculty of Organizational Sciences University of Belgrade Belgrade, Serbia boza@elab.rs ORCID ID 0000-0003-2111-7788 Sergei P. Prokhorov Institute for the History of Science and Technology Moscow, Russia sergei.prokhorov@gmail.com ORCID ID: 0000-0002-1874-8602 Abstract. The report is devoted to the history of the implementation of a successful Soviet- Yugoslav project—the creation of a hybrid computing complex HRS-100, which was successfully used to solve complex problems, in particular, the control of aircraft landing on the deck of a ship in a situation of heavy seas, the control of autonomous robots, as well as other studies. Keywords: analog computer, hybrid computer, simulation, HRS-100, history of computing. 1. Introduction. During the 1950s-1970s, computer development was closely tied to the ability of engineers to design the architecture and integrate available components. At the beginning, the focus was on analog computers. At the next stage, the capabilities of analog computers, capable of solving nonlinear systems of differential equations in real time, were successfully combined with the accuracy of digital computers into a new type of "hybrid computers" that found application in solving many problems. Hybrid systems were used to solve specific differential equations, control aircraft, nuclear reactors, chemical processes, control power supply systems, manage water resources, and model processes in industry, which were challenges for science and economics in Serbia at that time. During the period 1950-1970, Serbia was the leading Yugoslav republic in the research and development of analog computers. The military and nuclear ambitions of the Yugoslav leadership resulted in the decision to establish two research institutes: the Vinča Institute of Nuclear Sciences and the Mihailo Pupin Institute. The latter has become the country's leading research center in the field of computer science and information and communication technologies. In collaboration with professors from the Faculty of Organizational Sciences and the Faculty of Electrical Engineering of the University of Belgrade, a lot of work has been done to develop analog, digital and hybrid computers. At that time, Serbia was one of the five European countries that developed their own computers. At the same time, in the USSR, at the Institute of Automation and Telemechanic, the idea of combining analog and digital computers into a single computing system arose. This was due to the fact that the Soviet industry was faced with the problem of a sharp complication of control systems for many technological processes. Digital controllers and control computer systems have become widely used for control. It was necessary to find a technical solution for the development of algorithms and the practical implementation of object control systems, the dynamic behavior of which could not be simulated in real time on the then available digital machines. Therefore, the tasks of modeling objects were planned to be assigned to analog machines so that the control algorithms under study could be programmed on the digital part of the hybrid computing system. The intensive development of hybrid computers in the middle of the twentieth century is the result of work on solving problems in the field of object motion control, modeling and optimizing automatic control systems, developing complex simulators, etc. The individual use of analog and digital computers for this set of tasks turned out to be ineffective, therefore approaches that provide the best of both worlds. Hybrid computing systems are an attempt to combine the best of analog and digital technologies and avoid their shortcomings. [1][2] A hybrid computing system (HCS) is a complex of several computers or computing devices (analog and digital) united by a single control system for modeling complex systems, optimizing automatic control systems, solving nonlinear partial differential equations, etc. of the computational process on individual operations performed by AS and DS, reduces the amount of computational operations assigned to the