Concern about secret U.S. surveillance programs is fueling the development of another homegrown operating system in China, one that promises to offer a more secure alternative to rival OSes such as Android and Windows. The Linux-based COS, which stands for China Operating System, is just the latest OS to come out from the nation, at a time when Android and Windows are found on most smartphones and PCs in the country. The makers of the software have been vocal in wanting to break the U.S. hold over China's software market.