GNU Hurd is a collection of microkernel servers written as part of GNU, for the GNU Mach microkernel. It has been under development since 1990 by the GNU Project of the Free Software Foundation, designed as a replacement for the Unix kernel, and released as free software under the GNU General Public License. When the Linux kernel proved to be a viable solution, development of GNU Hurd slowed, at times alternating between stasis and renewed activity and interest.
MINIX is a Unix-like operating system based on a microkernel architecture. Since version 2.0, it has been POSIX compliant.
A monolithic kernel is an operating system architecture with the entire operating system running in kernel space. The monolithic model differs from other architectures such as the microkernel in that it alone defines a high-level virtual interface over computer hardware. A set of primitives or system calls implement all operating system services such as process management, concurrency, and memory management.
Plan 9 from Bell Labs is a distributed operating system which originated from the Computing Science Research Center (CSRC) at Bell Labs in the mid-1980s and built on UNIX concepts first developed there in the late 1960s. Since 2000, Plan 9 has been free and open-source. The final official release was in early 2015.
Squeak is an object-oriented, class-based, and reflective programming language. It was derived from Smalltalk-80 by a group that included some of Smalltalk-80's original developers, initially at Apple Computer, then at Walt Disney Imagineering, where it was intended for use in internal Disney projects. The group later was supported by HP Labs, SAP, and most recently, Y Combinator.
QNX is a commercial Unix-like real-time operating system, aimed primarily at the embedded systems market.
L4 is a family of second-generation microkernels, used to implement a variety of types of operating systems (OS), though mostly for Unix-like, Portable Operating System Interface (POSIX) compliant types.
The Internetworking Operating System (IOS) is a family of proprietary network operating systems used on several router and network switch models manufactured by Cisco Systems. The system is a package of routing, switching, internetworking, and telecommunications functions integrated into a multitasking operating system. Although the IOS code base includes a cooperative multitasking kernel, most IOS features have been ported to other kernels, such as Linux and QNX, for use in Cisco products.
OSF/1 is a variant of the Unix operating system developed by the Open Software Foundation during the late 1980s and early 1990s. OSF/1 is one of the first operating systems to have used the Mach kernel developed at Carnegie Mellon University, and is probably best known as the native Unix operating system for DEC Alpha architecture systems.
The V operating system is a discontinued microkernel distributed operating system that was developed by faculty and students in the Distributed Systems Group at Stanford University from 1981 to 1988, led by Professors David Cheriton and Keith A. Lantz. V was the successor to the Thoth operating system and Verex kernel that Cheriton had developed in the 1970s. Despite similar names and close development dates, it is unrelated to UNIX System V.
XNU is the computer operating system (OS) kernel developed at Apple Inc. since December 1996 for use in the Mac OS X operating system and released as free and open-source software as part of the Darwin OS, which, in addition to being the basis for macOS, is also the basis for Apple TV Software, iOS, iPadOS, watchOS, visionOS, and tvOS.
JavaOS is a discontinued operating system based on a Java virtual machine. It was originally developed by Sun Microsystems. Unlike Windows, macOS, Unix, or Unix-like systems which are primarily written in the C programming language, JavaOS is primarily written in Java. It is now considered a legacy system.
ChorusOS is a microkernel real-time operating system designed as a message passing computing model. ChorusOS began as the Chorus distributed real-time operating system research project at the French Institute for Research in Computer Science and Automation (INRIA) in 1979. During the 1980s, Chorus was one of two earliest microkernels and was developed commercially by startup company Chorus Systèmes SA. Over time, development effort shifted away from distribution aspects to real-time for embedded systems.
HelenOS is an operating system based on a multiserver microkernel design. The source code of HelenOS is written in C and published under the BSD-3-Clause license.
A hybrid kernel is an operating system kernel whose architecture attempts to combine aspects and benefits of microkernel and monolithic kernel architectures used in operating systems.
Visual Studio Tools for Applications (VSTA) is a set of tools that independent software vendors (ISVs) can use to build customization abilities into their applications for both automation and extensibility. Those customization abilities can be used by end-users to tailor the ISV's application within a managed extensibility environment just like Visual Basic for Applications.
The kernel is a computer program at the core of a computer's operating system and generally has complete control over everything in the system. The kernel is also responsible for preventing and mitigating conflicts between different processes. It is the portion of the operating system code that is always resident in memory and facilitates interactions between hardware and software components. A full kernel controls all hardware resources via device drivers, arbitrates conflicts between processes concerning such resources, and optimizes the utilization of common resources e.g. CPU & cache usage, file systems, and network sockets. On most systems, the kernel is one of the first programs loaded on startup. It handles the rest of the startup as well as memory, peripherals, and input/output (I/O) requests from software, translating them into data-processing instructions for the central processing unit.
Phantom OS is an orthogonally persistent managed code general-purpose operating system. It is based on a concept of persistent virtual memory, and executes bytecode in a virtual machine. It is one of a few OSes not based on the classic concepts of Unix-like systems. Phantom is based on the principle that "Everything is an object", in contrast to the Unix-like approach of "Everything is a file".
Redox is a Unix-like microkernel operating system written in the programming language Rust, which has a focus on safety, stability, and performance. Redox aims to be secure, usable, and free. Redox is inspired by prior kernels and operating systems, such as SeL4, MINIX, Plan 9, BSD, and Linux. It is free and open-source software distributed under an MIT License.
Genode is a free and open-source software operating system (OS) framework consisting of a microkernel abstraction layer and a set of user space components. The framework is notable as one of the few open-source operating systems not derived from a proprietary OS, such as Unix. The characteristic design philosophy is that a small trusted computing base is of primary concern in a security-oriented OS.
