Comparisons with Systems of Interest

This chapter presents a comparison of a number of operating systems with Alpha. It explores systems such as Hydra, StarOS, Cronus, Eden, Argus, Accent, and Locus. A number of general observations can be made concerning this set of systems. None is concerned with real-time control, and none is physically decentralized and logically centralized. All of these systems provide some form of location-transparent communication based on globally unique logical identifiers. The Cronus, Accent, and Locus systems involve low-level communications work, that is, they do not use standard communication protocols or facilities. Hydra was a capability-based, object-oriented operating system kernel that was constructed on the C.mmp multiprocessor. StarOS was one of two operating systems built on the CM * multiprocessor, the other being Medusa. StarOS is an object-oriented, capability-based operating system that was significantly influenced by Hydra. Cronus is an object-oriented constituent operating system, running on a heterogeneous collection of machines connected by one or more internetworked local area networks. The Eden system was constructed at the University of Washington by Guy Almes, et al ., from 1980 to 1985. Argus is a language for the construction of distributed programs, being developed by Barbara Liskov, et al . at MIT since 1979. Accent was designed as the basis for a large scale network of high-performance personal workstations. The Locus system began as an attempt to extend the UNIX file system across multiple machines and ended up becoming a distributed UNIX system.