One of the goals for the creation of Open C Environment for implementation of OSI is portability and environment independence. Two basic categories of target environments are identified.
The Hosted-Environment is an environment in which the existance of an operating system and multitasking capabilities may be assumed. The availability of facilities such as scheduling, timers, synchronization and dynamic memory allocation are often available in Hosted-Environments. UNIX, VMS, MS-DOS and VRTX are examples of hosted environments.
The Unhosted-Environment is an environment in which the existance of no facilities may be assumed. The underlying environment should at least provide:
Bare, intelligent, front-end processors are examples of Unhosted-Environments.
Open C Environment is designed to exist in Hosted and Unhosted environments. In Hosted-Environments, the interface to host facilities should be mapped on to the Open C Platform interface definitions. Design of OCE does consider well-behaved existance in Hosted-Environments.
The type of environment specific facilities defined in OCE are basic and simple. These facilities can easily be implemented from scratch in Un-Hosted environments.