Most, if not all, currently popular operating systems are designed to be general purpose environments for the development, maintenance, documentation and execution of systems of all types. Thus, the designers of the operating system must try to make the system a compromise between efficiency and power in all of these areas. This paper suggests that a class of operating systems and tools be designed to deal specifically with the problems of software design and development only. The fact that only the development tools themselves, and not the systems under development, are required to run fast and efficiently in the development environment is stressed as providing significantly different weight to the various considerations of operating system design. Since many of the problems of run time efficiency are no longer quite so pressing, additional power can be given to the operating system so that it may better support the software design and development process. / M.S.