Analog Computing…On Digital Machines

MADDIDA (Magnetic Drum Digital Differential Analyzer) prototype

MADDIDA, developed for a nuclear missile design project, used digital electronics. Tracks on a magnetic drum did the mathematical integration. MADDIDA was flown across the country for a demonstration to John von Neumann, who was impressed.

Analog Computing…On Digital Machines

Engineers at Northrop Aircraft recognized in 1949 that analog computations could be done digitally by replacing a differential analyzer’s mechanical wheel-and-disk integrators with binary adders.

These “Digital Differential Analyzers,” or DDAs, were digital computers that acted like analog computers, but were more precise. They were used for real-time control applications, as well as simulations of airplane and missile designs—often paired with slower general-purpose digital computers.

A dozen Northrop employees formed Computer Research Corporation to build small airborne DDAs. The Polaris missile used one of the first digital computers for on-board guidance.

MADDIDA Customer Demonstration

Northrop was initially reluctant to make MADDIDA a product. But by the end of 1952, six had sold, making MADDIDA the most popular commercial digital electronic computer. No other computer had sold as well.

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TRICE computer

TRICE, unlike other DDAs (Digital Differential Analyzer), operated in parallel, more like traditional analog computers. Each module was a solid-state computing element that functioned independently. DDAs that process each operation in sequence were less expensive, but slower.

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TRICE advertisement from Datamation

TRICE was the pinnacle of big hybrid DDAs (Digital Differential Analyzer). The $89,500 price bought only the starter system. Customers were firms like North American Aviation and NASA.

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