A computer system and method for operating a computer system is provided which comprises a core operating system and a system space having a number of memory locations. The core operating system is arranged to create a number of protection domains to partition the system space into a core operating system space and a plurality of partitions. A partition operating system, a partition user application, and a partition alarm handler is provided in each partition. Each partition operating system provides resource allocation services to the respective partition user application within the partition. An alarm dispatcher and a system alarm handler is provided in the core operating system space. The alarm dispatcher is configured to receive alarms and to dispatch the alarms to one of the alarm handlers.