Magnetic Drum Digital Differential Analyzer

The MADDIDA, short for Magnetic Drum Digital Differential Analyzer, was a special-purpose digital computer built to solve systems of ordinary differential equations. It was the first computer to represent bits using voltage levels, and the first whose entire logic was specified in Boolean algebra. It was invented by Floyd Steele and developed at Northrop Aircraft Corporation between 1946 and 1949 as a possible guidance system for the Snark missile. No guidance system resulted from the work, and the machine was used for aeronautical research instead. In 1952 it became the best-selling commercial digital computer in the world, although it was a special-purpose machine, with six units sold; the general-purpose UNIVAC I delivered its seventh unit only in 1954.