Fast, no-kernel, single address space, data-centric, preemptive multithreaded, persistent, secure, multi-user operating system, with Crush function-based programming safe-language. Some code available. [Open Source, Artistic]

Fast, single privilege, single address space, preemptive multithreaded, persistent, data-centric, secure, multiuser OS, with safe language, reconfigurable graphical interface.

Research OS coded in C++, architecture organized as frameworks of objects hierarchically classed by function, performance; customized by replacing subframeworks, objects; application interface is kernel objects exported via application/kernel protection layer; kernel and application objects examined via application browsers; runs on bare hardware on distributed and parallel computers. Virtual Choices (VChoices) also runs under Unix System V.

The usual variety of lively opinions, some of which are informed by study and quite insightful and useful in further understanding BRiX. [Slashdot]

Short, annotated, alphabetically sorted list and links, part of larger system.

Dynamically extensible, Exokernel-based, provides many core services: scheduler, kernel threads, domains, event dispatcher, security mechanisms, primitive VM operations. Blurs distinction between kernels and applications, which traditionally live in user-level address spaces, separated from kernel resources and services by an expensive protection boundary. Lets applications specialize the kernel by dynamically linking new code into running systems.