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The Shocking Truth Behind Arnold Nordsieck’s Differential Analyzer

To program this electromechanical computer, you plugged in the cords in specific patterns—and with extreme caution

2 min read
Photo of the analog computer that Arnold Nordsieck built.
Photo: Mark Richards/Computer History Museum

imgPhoto: Mark Richards/Computer History Museum

In 1950, the physicist Arnold Nordsieck built himself this analog computer. Nordsieck, then at the University of Illinois, had earned his Ph.D. at the University of California, Berkeley, under Robert Oppenheimer. To make his analog computer for calculating differential equations, the inventive and budget-conscious Nordsieck relied on US $700 worth of military surplus parts, particularly synchros—specialized motors that translate the position of the shaft into an electrical signal, and vice versa.

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polaroid sx-70 camera, silver with brown leather, open on white surface
Thomas Backa

In one corner stood the defending champion, Texas Instruments. In the other stood the challenger, Fairchild Semiconductor. The referee, judge, promoter, and only spectator was Polaroid. In contention was the contract for the electronics of Polaroid’s secret project—a pioneering product introduced in 1972 as the SX-70, a camera eventually purchased by millions of people.

As the embodiment of truly automated instant photography, the SX-70 fulfilled a long-held dream of Edwin Land, founder of Polaroid Corp., Cambridge, Mass. Vital to this “point and shoot” capability was a new film—one that would develop while exposed to light and so eliminate the tear-away covers of previous Polaroid films. Also vital were sophisticated electronics to control all single lens reflex (SLR) camera functions, including flashbulb selection, exposure control, mirror positioning, start of print development, and ejection of print. These circuits were divided into three modules, one each for motor, exposure and logic, and flash control. At the final count, some 400 transistors were used.

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