Roberts's first real experience with computers came while at Oklahoma State University where engineering students had free access to an IBM 1620 computer. His office at the Weapons Laboratory had the state of the art Hewlett-Packard 9100A programmable calculator in 1968. Roberts had always wanted to build a digital computer and, in July 1970, Electronic Arrays announced a set of six LSI integrated circuits that would make a four-function calculator. Roberts was determined to design a calculator kit and got fellow Weapons Laboratory officers William Yates and Ed Laughlin to invest in the project with time and money.