Jay Wright Forrester and the Origins of Whirlwind
Jay Wright Forrester, the principal designer behind the pioneering Whirlwind computer, grew up on a cattle ranch in Anselmo, Nebraska. As a child, he built a 12-volt electrical system to power the ranch using old car parts and a wind-driven generator – early signs of his talent for engineering.
Forrester went on to study electrical engineering, first at the University of Nebraska before completing his graduate work at MIT working on servomechanisms – electronic control systems. In 1944, he was recruited by MIT‘s Servomechanisms Laboratory for a project to build an advanced flight simulator for the Navy. The goal was to test aerodynamic stability in aircraft designs, with pilots sitting in a cockpit and the simulator mechanically responding to their joystick inputs.
Forrester‘s team began developing a large-scale analog computer to achieve this, but quickly ran into limitations of speed, accuracy and flexibility. After hearing about the capabilities of early digital computers like ENIAC and EDVAC, Forrester was inspired that digital computation could overcome these challenges. In 1946, the Whirlwind computer project was initiated to create one of the world‘s first real-time digital computers capable of powering such a flight simulator.
Revolutionary Design of Whirlwind
Several of Forrester‘s design decisions for Whirlwind broke new ground in computer capabilities. Rather than using bit serial architecture like EDVAC, Whirlwind was a 16-bit parallel system. This allowed faster speeds but required far more valve circuitry. After discovering that traditional valve manufacturing methods caused rapid failures, Forrester pioneered techniques that extended valve lifespans from 500 hours to 500,000 – a critical innovation.
After considering alternatives like CRT displays and mercury delay lines, Forrester began developing an entirely novel form of memory – magnetic core memory. Small ferrite cores held their magnetization state to store bits and were arranged on a grid with wires running through them. This random access memory using coincident currents was incredibly reliable and low cost at scale. Installed in 1953, Whirlwind‘s 2048 x 16 bit magnetic core memory doubled its speed to 40,000 instructions per second.
Groundbreaking Capabilities
Upon its completion in 1951 after nearly 5 years of intensive development, Whirlwind was remarkably advanced among the early computers:
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It was the first real-time computer, capable of receiving input data and delivering output fast enough for interactive use. This enabled its utilization for true flight simulation.
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Using over 4,000 vacuum tubes, it could add two 16-bit numbers in just 2 microseconds – blindingly fast computation for the era. Multiplication took only 20 microseconds.
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The initial configuration included 4KB of storage, upgradable to 8KB with the addition of a magnetic drum supplementing the main magnetic core memory. Massive capacity for its time.
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Whirlwind featured one of the earliest computer graphical displays, a 16-inch CRT screen with a resolution of 256 x 256 dots. It was accompanied by a pioneering light pen input device developed specifically for use with the display.
After losing Navy funding in 1951, Whirlwind found an ideal role in the new SAGE air defense system starting in 1953. Its fast real-time capabilities were perfectly suited to processing radar data and tracking aircraft. It remained in service as part of America‘s nuclear early warning systems into the 1980s.
The innovations of Whirlwind like magnetic core memory and real-time interactivity went on to influence decades of future computer advancements. Jay Forrester himself is considered a pillar of electrical engineering and computing history.
