Abstract: A maintenance management system includes an installation unit which installs a plurality of model data corresponding to maintenance objects, interconnected by a network, into a virtual three-dimensional space, the plurality of model data correlating the maintenance objects with positions in the virtual three-dimensional space. A display unit displays images of the maintenance objects in the virtual three-dimensional space at the positions based on the plurality of model data.

Abstract: In a lock control method for a system having a plurality of CPUs and a resource, identification information concerning one of CPUs is written into a non-class lock area of a first lock control information when there is no identification information in the first lock control information, so that the above CPU can acquire the right to exclusively use the whole resource. The identification information concerning one of the CPUs is written into the class lock area of the first lock control information, and thereafter the identification information concerning the CPU is written into a second lock control information when there is no identification information in a non-class lock area of the first lock control information, so that the CPU can acquire the right to exclusively use the resource for each of the classes thereof.