In currently used operating systems hardware support is used to ensure the memory protection. The communication between protection domains is obviously slower than simple method invocations. Robust component-based services need a flexible system design and fast communication mechanism between different units of protection. We describe the Java operating system JX that uses the type safety of th...

Early type-safe operating systems were hampered by poor performance. Contrary to these experiences we show that an operating system that is founded on an object-oriented, type-safe intermediate code can compete with MMUbased microkernels concerning performance while widening the realm of possibilities. Moving from hardware-based protection to softwarebased protection offers new options for oper...

Operating systems must be flexible in their support for security policies, providing sufficient mechanisms for supporting the wide variety of real-world security policies. Such flexibility requires controlling the propagation of access rights, enforcing fine-grained access rights and supporting the revocation of previously granted access rights. Previous systems are lacking in at least one of t...

Sequencing flexibility refers to the possibility of interchanging the order in which required manufacturing operations are performed. In this paper, we address several issues related to the modeling, measurement and performance evaluation of this flexibility in manufacturing systems. In particular, we introduce several representation and measurement schemes for sequencing flexibility and discus...

Vol. 9 No. 4 1997 33 Database products and other applications impose heavy demands on physical memory. The newest version of DIGITAL’s OpenVMS Alpha operating system extends its very large memory (VLM) support and allows large caches to remain memory resident. OpenVMS Alpha version 7.1 enables applications to take advantage of both 64-bit virtual addressing and very large memories consistent wi...

The implementation of a real-time operating system for a small satellite project has an extensive list of pros and cons. A real time operating system’s multithreaded structure allows for the ability to design a complex software system with more flight capabilities and configuration options to support the success of mission goals. The increase in versatility and flexibility comes with the price ...

The ELETTRA control system front-end computers are presently based on 68k VME boards and the OS-9 operating system. In view of the construction of the new booster injector and of a smooth upgrade of the existing control system, PowerPC VME boards running Linux have been adopted. The new platform provides reliability, performance and flexibility, while the RTAI (Real Time Application Interface) ...