In July of 1981, a 3 year contract was let to BBN for “DOS Design and Implementation” of what eventually became known as the Cronus Distributed Computing Environment. It was the first operational implementation of heterogeneous distributed object computing. By the time it had run its course, Cronus was operational on hundreds of hosts at in excess of 25 sites, served as the basis for numerous operational, advanced concept distributed applications, and provided system training on distributed object computing to hundreds of engineers through week long Cronus workshop courses, run on more than 20 occasions. In 1985, BBN began a collaboration with Odyssey Research Associates to add multilevel security to Cronus. The resulting variant of Cronus was the first instance of a secure distributed OS. At first it was called simply “SDOS” but the name was later changed to THETA (“Trusted HETerogeneous Architecture”). In 1999, the Cronus system was honored with a Smithsonian Institution award for technical innovation and included in the Smithsonian's Permanent Research Collection on Information Technology, chronicling the history of computing.