At RCA throughout the 1940s Masterson made fundamental audio-recording contributions, ranging from sound-on-film through wire, tape, and 45-rpm-disk systems. Masterson was one of the first employees hired by Univac, whose founders in 1947 had developed ENIAC, the giant machine that gave birth to the computer age - widely seen as the first fully programmable electronic computer. He was present in November 1952 when Walter Cronkite, in a TV broadcast from Univac’s Philadelphia plant, used computing power for the first time to predict the outcome of a presidential election - a substantial win for Dwight Eisenhower over Adlai Stevenson. This first Univac computer was a eight-foot-tall, 30 ton machine. At Univac he developed the peripheral equipment needed for the Univac computers. At the beginning of the 21 st Century, when Masterson’s stepson took him to buy a new computer, Masterson asked a salesman how much a printer would cost. He told him $125. "The first printer I ever made and sold cost $145,000!" Masterson said. His expensive, high speed (for 1954) printer was developed at Univac. He also helped develop the vacuum-tube Univac computer. In 1963, he left Univac for Honeywell, and by the early 1970s he was in Minneapolis, where he rose to head the entire operation for developing peripheral computer equipment, such as printers, tape drives and mass storage. Near the end of this time at Honeywell, he ventured into the medical field and designed an electronic system for analyzing white blood cells – an"automated microscope," as he put it. He retired in 1977 to a consulting business, building prototypes of devices in his basement that clients would then turn into marketable products. Among his inventions was a device that uses sound to loosen phlegm in the chests of cystic fibrosis patients.