TRIX (operating system)

On startup, the NuMachine would load the same program on each CPU in the system, passing each instance the numeric ID of the CPU it was running on. TRIX relied on this design to have the first CPU set up global data structures and then set a flag to signal that initialization was complete. After that, each instance of the kernel was able to access global data. The designers were aware of designs that would have alleviated the contention. Indeed, TRIX's original design used a nonblocking message passing mechanism, but "this implementation was found to have deficiencies often overlooked in the literature," including poor performance. Although the TRIX operating system was first implemented on the NuMachine, this was due to the availability of the NuMachine at MIT, not because of any characteristic of the architecture. The system was designed to be easily portable. It was implemented largely in C with little assembly code. The mutual exclusion primitive could be ported to any architecture with an atomic test and set instruction. ==Attempted use by the GNU Project==

Richard Stallman mentions in the 1985 GNU Manifesto that "an initial kernel exists" for the GNU operating system, "but many more features are needed to emulate Unix." This was a reference to TRIX's kernel, which TRIX's authors had decided to distribute as free software. The features Stallman wished to add (file versioning, undeletion, information on when and how and where the file was backed up on tape, atomic file updates) were not generally associated with Unix. In December 1986, developers used TRIX's kernel as a base in their first attempt to create a kernel for GNU. They eventually decided Trix was unusable as a starting point, primarily because: • it only ran on "an obscure, expensive 68000 box", and would therefore require porting to other architectures, and • it was decided that the Mach microkernel was a better underlying design for a server-based operating system. This second attempt evolved into the GNU Hurd. ==See also==