   mach  is a kernel developed at carnegie mellon university to support operating system research, primarily distributed and parallel computation. although mach is often mentioned as one of the earliest examples of a microkernel, not all versions of mach are microkernels. mach's derivatives are the basis of the modern operating system kernels in mac os x (which is not a microkernel, ) and gnu hurd (which is a microkernel). the project at carnegie mellon ran from 1985 to 1994, ending with mach 3.0, which is finally a true microkernel. mach was developed as a replacement for the kernel in the bsd version of unix, so no new operating system would have to be designed around it. experimental research on mach appears to have ended, although mach and its derivatives exist within a number of commercial operating systems. these include nextstep and openstep, upon which mac os x is based â all using the xnu operating system kernel which incorporates an earlier, non-microkernel, 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. neither mac os x 
Carnegie_Mellon_University_software Mach_(kernel) Microkernels