Network Operating System, written by William Yeager, a staff research engineer at Stanford's medical school. Distinguishing features of NOS were that it was written in C and that it was multi-tasking capable; this allowed additional network interfaces and additional features to be easily added as new tasks. NOS was the basis of Cisco's IOS operating system. In 1987, Stanford licensed the router software and two computer boards to Cisco, after investigations by Stanford staff members such as Les Earnest. References External links Router man, an interview with William Yeager ARPANET History of the Internet Stanford University