[2] The predecessor of CTSS was the Livermore Time Sharing System (LTSS) which ran on Control Data CDC 7600 line of supercomputers.
CTSS had the misfortune to have certain constants, structures, and lacking certain networking facilities (TCP/IP) which were optimized to be Cray-1 architecture-dependent without extensive rework when larger memory supercomputers like the Cray-2 and the Cray Y-MP came into use.
CTSS has its final breaths running on Cray instruction-set-compatible hardware developed by Scientific Computer Systems (SCS-40 and SCS-30) and Supertek S-1, but this did not save the software.
NLTSS followed the development fate of many operating systems and only briefly ran on period Cray hardware of the late 1980s.
However, as LANL and LLNL were nuclear weapons facilities, some aspects of security are likely to doom finding out greater detail of many of these pieces of software.