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Mach (kernel) AI simulator
(@Mach (kernel)_simulator)
Hub AI
Mach (kernel) AI simulator
(@Mach (kernel)_simulator)
Mach (kernel)
Mach (/mɑːk/) is an operating system kernel developed at Carnegie Mellon University by Richard Rashid and Avie Tevanian to support operating system research, primarily distributed and parallel computing. Mach is often considered one of the earliest examples of a microkernel. However, not all versions of Mach are microkernels. Mach's derivatives are the basis of the operating system kernel in GNU Hurd and of Apple's XNU kernel used in macOS, iOS, iPadOS, tvOS, and watchOS.
The project at Carnegie Mellon ran from 1985 to 1994, ending with Mach 3.0, which is a true microkernel. Mach was developed as a replacement for the kernel in the BSD version of Unix, not requiring a new operating system to be designed around it. Mach and its derivatives exist within several commercial operating systems, including all those using the XNU operating system kernel, which incorporates an earlier non-microkernel version of Mach as a major component. The Mach virtual memory management system was also adopted in 4.4BSD by the BSD developers at CSRG, and appears in modern BSD-derived Unix systems such as FreeBSD.
Mach is the logical successor to Carnegie Mellon's Accent kernel. Mach's lead developer Richard Rashid has been employed at Microsoft since 1991; he founded the Microsoft Research division. Co-founding Mach developer Avie Tevanian, was formerly head of software at NeXT, then Chief Software Technology Officer at Apple Inc. until March 2006.
The developers rode bicycles to lunch through rainy Pittsburgh's mud puddles, and Tevanian joked the word "muck" could form a backronym for their Multi-User (or Multiprocessor Universal) Communication Kernel. Italian CMU engineer Dario Giuse later asked project leader Rick Rashid about the project's current title and received "MUCK" as the answer, though not spelled out but just pronounced /mʌk/. According to the Italian alphabet, he wrote "Mach". Rashid liked Giuse's spelling "Mach" so much that it prevailed.
A key concept in the original Unix operating system is the idea of a pipe. A pipe is an abstraction allowing data to be moved as an unstructured stream of bytes between programs. Using pipes, users can link together multiple programs to complete tasks, feeding data through several consecutive small programs. This contrasts with typical operating systems of the era, which require a single large program that can handle the entire task, or alternately, used files to pass data, which was resource-expensive and time-consuming.[citation needed]
Pipes were built on the underlying input/output system. This system is, in turn, based on a model where drivers are expected to periodically "block" while they wait for tasks to complete. For instance, a printer driver might send a line of text to a line printer and then have nothing to do until the printer completes printing that line. In this case, the driver indicates that it was blocked, and the operating system allows some other program to run until the printer indicates it is ready for more data. In the pipes system the limited resource was memory, and when one program filled the memory assigned to the pipe, it would naturally block. Normally this would cause the consuming program to run, emptying the pipe again. In contrast to a file, where the entire file has to be read or written before the next program can use it, pipes made the movement of data across multiple programs occur in a piecemeal fashion without any programmer intervention.[citation needed]
However, implementing pipes in memory buffers forced data to be copied from program to program, a time-consuming and resource intensive operation. This made the pipe concept unsuitable for tasks where quick turnaround or low latency was needed, such as in most device drivers. The operating system's kernel and most core functionality was instead written in a single large program. When new functionality, such as computer networking, was added to the operating system, the size and complexity of the kernel grew, too.[citation needed]
Unix pipes offered a conceptual system that could be used to build arbitrarily complex solutions out of small cooperating programs. These smaller programs were easier to develop and maintain, and had well-defined interfaces that simplified programming and debugging. These qualities are even more valuable for device drivers, where small size and bug-free performance was extremely important. There was a strong desire to model the kernel on the same basis of small cooperating programs.[citation needed]
Mach (kernel)
Mach (/mɑːk/) is an operating system kernel developed at Carnegie Mellon University by Richard Rashid and Avie Tevanian to support operating system research, primarily distributed and parallel computing. Mach is often considered one of the earliest examples of a microkernel. However, not all versions of Mach are microkernels. Mach's derivatives are the basis of the operating system kernel in GNU Hurd and of Apple's XNU kernel used in macOS, iOS, iPadOS, tvOS, and watchOS.
The project at Carnegie Mellon ran from 1985 to 1994, ending with Mach 3.0, which is a true microkernel. Mach was developed as a replacement for the kernel in the BSD version of Unix, not requiring a new operating system to be designed around it. Mach and its derivatives exist within several commercial operating systems, including all those using the XNU operating system kernel, which incorporates an earlier non-microkernel version of Mach as a major component. The Mach virtual memory management system was also adopted in 4.4BSD by the BSD developers at CSRG, and appears in modern BSD-derived Unix systems such as FreeBSD.
Mach is the logical successor to Carnegie Mellon's Accent kernel. Mach's lead developer Richard Rashid has been employed at Microsoft since 1991; he founded the Microsoft Research division. Co-founding Mach developer Avie Tevanian, was formerly head of software at NeXT, then Chief Software Technology Officer at Apple Inc. until March 2006.
The developers rode bicycles to lunch through rainy Pittsburgh's mud puddles, and Tevanian joked the word "muck" could form a backronym for their Multi-User (or Multiprocessor Universal) Communication Kernel. Italian CMU engineer Dario Giuse later asked project leader Rick Rashid about the project's current title and received "MUCK" as the answer, though not spelled out but just pronounced /mʌk/. According to the Italian alphabet, he wrote "Mach". Rashid liked Giuse's spelling "Mach" so much that it prevailed.
A key concept in the original Unix operating system is the idea of a pipe. A pipe is an abstraction allowing data to be moved as an unstructured stream of bytes between programs. Using pipes, users can link together multiple programs to complete tasks, feeding data through several consecutive small programs. This contrasts with typical operating systems of the era, which require a single large program that can handle the entire task, or alternately, used files to pass data, which was resource-expensive and time-consuming.[citation needed]
Pipes were built on the underlying input/output system. This system is, in turn, based on a model where drivers are expected to periodically "block" while they wait for tasks to complete. For instance, a printer driver might send a line of text to a line printer and then have nothing to do until the printer completes printing that line. In this case, the driver indicates that it was blocked, and the operating system allows some other program to run until the printer indicates it is ready for more data. In the pipes system the limited resource was memory, and when one program filled the memory assigned to the pipe, it would naturally block. Normally this would cause the consuming program to run, emptying the pipe again. In contrast to a file, where the entire file has to be read or written before the next program can use it, pipes made the movement of data across multiple programs occur in a piecemeal fashion without any programmer intervention.[citation needed]
However, implementing pipes in memory buffers forced data to be copied from program to program, a time-consuming and resource intensive operation. This made the pipe concept unsuitable for tasks where quick turnaround or low latency was needed, such as in most device drivers. The operating system's kernel and most core functionality was instead written in a single large program. When new functionality, such as computer networking, was added to the operating system, the size and complexity of the kernel grew, too.[citation needed]
Unix pipes offered a conceptual system that could be used to build arbitrarily complex solutions out of small cooperating programs. These smaller programs were easier to develop and maintain, and had well-defined interfaces that simplified programming and debugging. These qualities are even more valuable for device drivers, where small size and bug-free performance was extremely important. There was a strong desire to model the kernel on the same basis of small cooperating programs.[citation needed]