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The Whirlwind Project

A Complete History Of Mainframe Computing
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The Whirlwind Project

The Whirlwind project was ironic. It went way over budget, took much longer than intended, and was never used in its intended role, but was arguably one of the most important technological achievements in the computer field.

In 1943, when the US Air Force gave MIT's Jay Forrester the Whirlwind project, he was told to create a simulator to train aircraft pilots rather than have them learn by actually being in a plane. This intended use was very significant in that it required what we now call a "real-time system," as the simulator had to react quickly enough to simulate reality. While other engineers were developing machines that could process 1,000 to 10,000 instructions per second, Forrester had to create a machine capable of a minimum of 100,000 instructions per second. On top of this, because it was a real-time system, reliability had to be significantly higher than other systems of that time.

The project dragged on for many years, long after World War II had ended. By that time, the idea of using it for a flight simulator disappeared, and for a while, they weren't quite sure what this machine was being developed to do. That is, until the Soviets detonated their first nuclear bomb and the U.S. government decided to upgrade its antiquated and ineffective existing air defense system. One part of this was to develop computer-based command-and-control centers. The Whirlwind had a new life, and with so much at stake, funding would never be a problem.

Memory, however, was a problem. The mercury-delay line that others were using was far too slow, so Forrester decided to try a promising technology: electrostatic storage tubes. One problem he faced was that they did not yet exist, so a lot of development work had to be put into this before he would have a working product. But once it was completed, electrostatic storage tubes were deemed unreliable and their storage capacity was very disappointing. Consequently, Forrester, who was always looking for better technology, started work on what would later be called "core memory." He passed his work on to a graduate student also working on the project, called Bill Papian, who had a prototype ready by 1951 and a working product that replaced the electrostatic memory in 1953. It was very fast, very reliable, and did not even require electrical refreshes to hold its values. We'll talk more about core memory later, but suffice it to say, it was an extremely important breakthrough that quickly became the standard for well over a decade.

Core memory was the final piece of the puzzle. The computer was effectively complete in 1953 and first deployed in Cape Cod. Although it failed to reach the intended performance level, it was still capable of 75,000 instructions per second. This far exceeded anything available back then. The technology was transferred by MIT to IBM, where the production version was re-christened the IBM AN/FSQ-7 and saw production in 1956. These monsters had over 50,000 vacuum tubes, and weighed over 250 tons, which made them the largest computers ever built. It also consumed over a megawatt of power, not including the necessary air conditioning.

SAGE (Semi-Automatic Ground Environment), the bomber-tracking application for which the Whirlwind was now intended, became fully operational by 1963. Ironically, this was past the time when the Whirlwind was truly useful, since it was designed to track bombers, and by then, ICBMs had made their appearance a few years earlier. Nonetheless, while the actual uses for the Whirlwind were dubious, the technologies either created or accelerated by it were extremely important. These include not only the aforementioned core memory, but the development of printed circuits, mass-storage devices, computer graphics systems (for plotting the aircraft), CRTS, and even the light pen. Connecting these computers together gave the United States a big advantage in networking expertise and digital communications technologies. It even had a feature we lack in modern computers: a built-in cigarette lighter and ashtray. Clearly, it was worth the $8 billion that it cost to fully install SAGE, even though SAGE never helped intercept a single bomber.

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