This paper discussesthe design of the file system for DEMCS, an operating system being developed for the CRAY-1 somputer at Los Alamos Scientific Laboratory. The goals to be met, in particular the performance and usability considerations are outlined. A descriptionis given of the user interface and the general structure of the file systemand the file system routines. A simple model of program behavior is used to demonstrate the effet of buffer- ing data by the file system routines. A disk space allocation strategy is descibed which will take advantage of this buffering. The last section out- lines how the performance mechanisms are itegrated into the file system routines.

Mach is a multiproceesor operating system kernel and environment under development at Carnegie-Mellon University. Mach provides a new foundation for UNIX development that spans networks of uniprocessors and multiprocessors . This paper describes Mach and the motivations that led to its design. Also described are some of the details of its implementation and current status.