Shouldn't take more than a couple of man-years if you got the right people together. A C compiler is still pretty low down on the toolchain, and there is a whol

Shouldn't take more than a couple of man-years if you got the right people together. A C compiler is still pretty low down on the toolchain, and there is a whole library of literature explaining how the technology below this level works. I think the big restriction is how much existing technology you'd be allowed to use, and how functional/scalable the technology would have to be when you're done. I/O is a big hurdle. Do you have to design the graphics hardware yourself? Do you have access to modern photolitography? Are you required to create the monitor/keyboard yourself? Other input devices, like disk drives? Do you need presistent storage at all? Display? Etc.