<P> Embedded systems that have fixed deadlines use a real - time operating system such as VxWorks, PikeOS, eCos, QNX, MontaVista Linux and RTLinux . Windows CE is a real - time operating system that shares similar APIs to desktop Windows but shares none of desktop Windows' codebase . Symbian OS also has an RTOS kernel (EKA2) starting with version 8.0 b . </P> <P> Some embedded systems use operating systems such as Palm OS, BSD, and Linux, although such operating systems do not support real - time computing . </P> <P> Operating system development is one of the most complicated activities in which a computing hobbyist may engage . A hobby operating system may be classified as one whose code has not been directly derived from an existing operating system, and has few users and active developers . </P> <P> In some cases, hobby development is in support of a "homebrew" computing device, for example, a simple single - board computer powered by a 6502 microprocessor . Or, development may be for an architecture already in widespread use . Operating system development may come from entirely new concepts, or may commence by modeling an existing operating system . In either case, the hobbyist is his / her own developer, or may interact with a small and sometimes unstructured group of individuals who have like interests . </P>

Where are the operating system and programs stored when not in use