GNU Hurd
Before joining Microsoft in 1991, Rashid had been the developer of the Mach kernel during his tenure as a professor of computer science at Carnegie Mellon University. The Mach multiprocessor operating system kernel developed by Rashid has had a lasting influence in the design of modern operating systems, including the design of Windows NT, and remains at the core of several operating systems such as NeXTSTEP, GNU Hurd, macOS, iOS, OSF/1, and Tru64 UNIX.