Exos

Exos may refer to:

Rockets

Software

RM-86 Exos

The Exos, originally designated RM-86 and later PWN-4, was a sounding rocket developed by the University of Michigan and NACA for use by the United States Air Force.

History

Developed by the University of Michigan for use by the Air Force Cambridge Research Center, Exos used a three-stage configuration, consisting of a first-stage rocket from an Honest John rocket, a second stage from a Nike-Ajax surface-to-air missile, and a Thiokol XM19 upper stage. It was designated XRM-86 in April 1959, and redesignated PWN-4A in June 1963.

Utilising a rail launcher, the first launch of a full Exos vehicle took place in June 1958, launched from the Wallops Flight Facility. Eight operational launches took place between 1960 and 1965, launched from Eglin Air Force Base.

Launch history

References

Exokernel

Exokernel is an operating system kernel developed by the MIT Parallel and Distributed Operating Systems group, and also a class of similar operating systems.

Operating System Kernels generally present the hardware-resources to applications through high level abstractions such as the (virtual) file-system. The idea behind exokernels is to force as few abstractions as possible on developers, enabling them to make as many decisions as possible about hardware abstractions. Exokernels are tiny, since functionality is limited to ensuring protection and multiplexing of resources, which are vastly simpler than conventional microkernels' implementation of message passing and monolithic kernels' implementation of abstractions.

Implemented applications are called library operating systems; they may request specific memory addresses, disk blocks, etc. The kernel only ensures that the requested resource is free, and the application is allowed to access it. This low-level hardware access allows the programmer to implement custom abstractions, and omit unnecessary ones, most commonly to improve a program's performance. It also allows programmers to choose what level of abstraction they want, high, or low.