The safety and reliability of the operation of materials on which modern cyber systems are developed and new autonomous cyber devices are created that are capable of performing tasks in modern combat conditions was considered. Mathematical modeling of critical phenomena in semiconductor solid solutions of elements of groups III – V of the periodic system under various operating conditions was performed. The properties of the AxB1-xCyD1-y type semiconductor solid solutions were predicted. The spaces, in which the conditions of stable and unstable phases are satisfied, as well as areas of coexistence of several phases simultaneously, were determined on sections of phase diagrams. A computer modeling technique for the formation of critical spaces, based on the use of a differential topological approach in complex multicomponent systems, was used. A method for determining the total derivatives of the free energy of quaternary solid solutions with mixing in two sublattices from the third to the eighth inclusive using the regular solution model and standard thermodynamic functions for binary compounds was applied to describe the interaction of atoms in multicomponent solid solutions.Sections of the phase diagram of the In-Ga-As-P system, critical spaces and phase coexistence spaces in four-dimensional space for various temperatures were calculated. The possibility of forming regions of coexistence of phases of different orders in solid solutions InxGa1-xAsyP1-y is shown by the obtained modeling results. The results obtained are consistent with the available experimental data, in which spatial modulation of the composition of the solid solution was observed.