This document discusses different operating systems that support embedded systems. It begins by defining embedded systems and their increasing use in various applications like consumer electronics, medical devices, transportation systems, and wireless sensor networks. It then examines several commonly used operating systems for embedded systems like QNX, Windows CE, Linux, and domain-specific operating systems for sensor networks. For each OS, it provides details on features like architecture, scheduling algorithms, memory management, and language support. It concludes by characterizing embedded systems as either standalone or networked systems and provides examples of each type.