"The search for the lost Cray supercomputer OS"

One of the most historically significant operating systems that?s likely to be in the ?not to be found? category would be THE. (See ?The THE Operating system? by Dijkstra. It is where the principles of ring based design and synchronizing by semaphores was invented.) Maybe, just maybe, it might exist in the form of listings, and since it?s a fairly small body of assembly language code that might be good enough. Then there would be the problem of the emulation, though I do know one is being worked on, and at least one real machine might also still exist. Come to think of it, I recently read a document about the first Algol-60 compiler ? consisting of a design description, the full (assembly language) source code, and a Pascal equivalent.