[1] In 1956, he joined the Massachusetts Institute of Technology (MIT)'s Lincoln Laboratory to help design the Semi-Automatic Ground Environment (SAGE) air defense system.
During this time, he was responsible for developing the "first pen-based computer system that reliably recognized cursive writing"[2] and the first spell checker.
Under founding director John McCarthy, he became involved with the Advanced Research Projects Agency Network (ARPAnet) startup committee.
He made significant contributions in the fields of robotics through the creation of systems that coupled computer vision with prosthetic and vehicular applications.
[1] Following SAIL's merger with the University's computer science department in 1980, Earnest left Stanford to serve as the founding president and director of Imagen Corp. in Santa Clara, California.