After basic training, Roberts attended the Cryptographic Equipment Maintenance School at Lackland Air Force Base in San Antonio, Texas. Because of his electrical engineering studies at college, Roberts was made an instructor at the Cryptographic School when he finished the course. To augment his meager enlisted man's pay, Roberts worked on several off-duty projects and even set up a one-man company, Reliance Engineering. The most notable job was to create the electronics that animated the Christmas characters in the window display of Joske's department store in San Antonio. In 1965, he was selected for an Air Force program to complete his college degree and become a commissioned officer. Roberts earned an electrical engineering degree from Oklahoma State University in 1968 and was assigned to the Laser Division of the Weapons Laboratory at Kirtland AFB in Albuquerque, New Mexico. In 1968, he looked into applying to medical school but learned that, at age 27, he was considered too old.