🚀 go-pugleaf

To further answer the question about how long it took to port UNIX to the  
Cray-2, I have some more information.

From the time that the decision was made to the time it was up and running
was about 1 calendar year.  The project used 12 people and involved first
porting to the XMP.  The XMP port took three months.  The port to the 
Cray-2 involved the creation of the simulator, new compilers and other new
tool, all for a new architecture that nobody had ported anything to.
The whole project went very smoothly, and I am told that the people involved
are very proud.
I would also like to further expand on my comment about the removal of 
features of UNIX.  Some UNIX functionality was removed that did not make 
sense under the new architecture.  Some forms of interprocess communication
depending on virtual memory for instance.  Since the 2 does not have virtual
memory, to provide the equivalent functionality would not have been practical.
Rest assured, however, UNICOS on the Cray-2 is UNIX in all important 
particulars.

Brian Utterback
Cray Research Inc.

The above opinions are my own and not those of my employers.