Magnetic Drum Digital Differential Analyzer

Development on the project began in March 1946 at Northrop Corporation with the goal of producing a subsonic cruise missile designated "MX-775", which came to be called the Snark.Ulmann 2013, p. 164. Northrop's parameters for this project were to create a guidance system that would allow a missile to hit a target at a distance of up to {{convert|5000|mi}} with a precision that would be {{convert|200|yd}} better than the German "vengeance" weapons V1 and V2.Ulmann 2013, p. 164. However, the MADDIDA was never used in weaponry,Ulmann 2013, p. 164. and Northrop ultimately used a different analog computer as the guidance system for the Snark missile.Ceruzzi 1989, p. 25.

Part of the project parameters involved developing the first digital data analyzer (DIDA).Reilly 2003, p. 163.

Physicist Floyd Steele, who had reportedly in 1946 already demonstrated a working DIDA before the press in 1946 in his Los Angeles home, was hired as conceptual leader of the design group.Reilly 2003, p. 164. Steele developed the concept for the DIDA, which would entail implementing an analog computer using only digital elements.Ulmann 2013, p. 164. When the decision was made to use magnetic drum memory (MAD) for the DIDA, the name was lengthened to MADDIDA (pronounced "Mad Ida").Reilly 2003, p. 163.

In his design for MADDIDA, Steele was influenced by the analog computer invented in 1927 by Vannevar Bush, which had digital components.Reilly 2003, p. 164. Another influence was Lord Kelvin's tide-predicting machine, an analog computer completed in 1873.Reilly 2003, p. 164.

Steele hired Donald Eckdahl, Hrant (Harold) Sarkinssian, and Richard Sprague to work on the MADDIDA's germanium diode logic circuits and also to do magnetic recording.Reilly 2003, p. 164. Together, this group developed the MADDIDA prototype between 1946 and 1949.

The MADDIDA had 44 integrators implemented using a magnetic drum with six storage tracks. The interconnections of the integrators were specified by writing an appropriate pattern of bits onto one of the tracks.Computer History Museum, Artifact Catalog

In contrast to the prior ENIAC and UNIVAC I computers, which used electrical pulses to represent bits, the MADDIDA was the first computer to represent bits using voltage levels.Reilly 2003, p. 164. It was also the first computer whose entire logic was specified in Boolean algebra.Reilly 2003, p. 164. These features were an advancement from earlier digital computers that still had analog circuitry components."Annals of the History of Computing" 1988, p. 358

The original MADDIDA prototype is now part of the collection at the Computer History Museum in Mountain View, California.Reilly 2003, p. 164.

Ultimately, the MADDIDA was never used in weaponry.Ulmann 2013, p. 164. Northrop ended up using a different analog computing system to guide the Snark missile,Ceruzzi 1989, p. 25. a system that was so dubious that many missiles were lost. A missile launched in 1956 went so far off course that it landed in north-eastern Brazil and was not found until 1983.[https://news.google.com/newspapers?id=g5lVAAAAIBAJ&sjid=MkANAAAAIBAJ&dq=snark%20found%20brazil&pg=6689%2C2748525 "Long-lost missile found."] The Leader-Post, 15 January 1983. Retrieved: 6 January 2013. Many of those connected with the program commented in jest "That the Caribbean was full of 'Snark infested waters'".Zaloga 1993, p. 193.

After the MADDIDA design team left Northrop in 1950, another team, which included Max Palevsky, was hired to duplicate the machine for commercial distribution. By the end of 1952, six MADDIDAs had been delivered and installed,Reilly 2003, p. 164. making it the bestselling commercial digital computer in the world at the time.Computer History Museum, MADDIDA Customer Demonstration One of the six was sold to the Navy Electronics Laboratory (see above photo).

While developing the MADDIDA, the design team came to realize that a digital differential analyzer could be run on a general-purpose digital computer through the use of an appropriate problem-oriented language (POL), such as Dynamo.Reilly 2003, p. 164. A year after the first MADDIDA was demonstrated, Steele and the MADDIDA design team left Northrop, along with Irving S. Reed, in order to develop general-purpose computers.Reilly 2003, p. 164. On July 16, 1950, they formed the Computer Research Corporation (CRC), which in 1953 was sold to NCR.Reilly 2003, p. 164.

Max Palevsky, who later worked with the MADDIDA duplication team at Northrop, drew influence from the MADDIDA's design in his work in 1952–1956 building the Bendix G-15, an early personal computer, for the Bendix Corporation. In March 1957, Palevsky begin work at Packard Bell, at a new affiliate of the company he started called Packard Bell Computer Corp. Palevsky continued gaining commercial support for digital computing, allowing design advancement to continue. He retired as Director and chairman of the executive committee of Xerox in May 1972.http://www.hbs.edu/leadership/database/name/ Harvard Business School 20th Century American Leaders Database While Xerox would eventually drop personal computing, the Xerox prototypes would influence Steve Jobs and Steve Wozniak in their 1979 tour of the Xerox facilityhttp://zurb.com/article/801/steve-jobs-and-xerox-the-truth-about-inno Steve Jobs and Xerox: The Truth About Innovation.

• List of vacuum-tube computers

{{Reflist}}

• Ceruzzi, Paul E. (1989). "Beyond the Limits: Flight Enters the Computer Age" The MIT Press.
• Reilly, Edwin D. (2003). [https://books.google.com/books?id=JTYPKxug49IC&dq=Magnetic+Drum+Digital+Differential+Analyzer&pg=PA77 "Milestones in Computer and Science History"], Greenwood Publishing Group.
• Ulmann, Bernd. (2013). "Analog Computing" De Gruyter Oldenbourg.
• Annals of the History of Computing. Volume 9, Number 3/4. 1988.
• [http://www.computerhistory.org/revolution/analog-computers/3/159/441 Computer History Museum, Artifact Catalog: MADDIDA (Magnetic Drum Digital Differential Analyzer)]
• [http://www.computerhistory.org/revolution/analog-computers/3/159/424 Computer History Museum, MADDIDA Customer Demonstration]
• Zaloga, Steven J. "Chapter 5." Target America: The Soviet Union and the Strategic Arms Race, 1945–1964. New York: Presidio Press, 1993. {{ISBN|0-89141-400-2}}.

• {{Commons category-inline|Magnetic Drum Digital Differential Analyzer}}
• [http://www.computerhistory.org/revolution/analog-computers/3/159/441 MADDIDA (Magnetic Drum Digital Differential Analyzer) at the Computer History Museum]
• Milestones in Computer Science and Information Technology: [https://books.google.com/books?id=JTYPKxug49IC&dq=Magnetic+Drum+Digital+Differential+Analyzer&pg=PA77 Full Text Free at Google Books]

Category:Early computers

Category:Vacuum tube computers

Category:1940s computers