In this paper, we present real-time system software architecture, composed of an event-driven operating system called the Embedded Lightweight Operating System (ELOS) including fault tolerant self-configuration combined with a multi hop ad hoc routing protocol suite. In the ELOS, a conditional preemptive FCFS scheduling method with a guaranteed time slot is designed for efficient real-time processing. For more elaborate configurations, we reinforce fault tolerance by supplementing semi-auto configuration using wireless agent nodes, The developed hardware platform is also introduced, which is a scalable prototype constructed using offthe-shelf components. Finally, to verify real-time processing ability under the various traffic patterns, the performance of ELOS system on a ubiquitous network test-bed is evaluated. The result shows that the ELOS is more suitable for tiny ubiquitous networked systems with real-time constraints.