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This book presents an organizational and social history of one of the foundational projects of the computer era: the development of the SAGE (Semi-Automatic Ground Environment) air defense system, from its first test at Bedford, Massachusetts, in 1951, to the installation of the first unit of the New York Air Defense Sector of the SAGE system, in 1958. The idea for SAGE grew out of Project Whirlwind, a wartime computer development effort, when the U.S. Department of Defense realized that the Whirlwind computer might anchor a continent-wide advance warning system. Developed by MIT engineers and scientists for the U.S. Air Force, SAGE monitored North American skies for possible attack by manned aircraft and missiles for twenty-five years. Aside from its strategic importance, SAGE set the foundation for mass data-processing systems and foreshadowed many computer developments of the 1960s. The heart of the system, the AN/FSQ-7, was the first computer to have an internal memory composed of "magnetic cores," thousands of tiny ferrite rings that served as reversible electromagnets. SAGE also introduced computer-driven displays, online terminals, time sharing, high-reliability computation, digital signal processing, digital transmission over telephone lines, digital track-while-scan, digital simulation, computer networking, and duplex computing. The book shows how the wartime alliance of engineers, scientists, and the military exemplified by MIT's Radiation Lab helped to transform research and development practice in the United States through the end of the Cold War period.
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By Mel Beckman (Oxnard not just a pretty name, CA United States)
I kind of expected this book to be the typical Smithsonian-style broad-stroke history of Whirlwind and the surrounding SAGE project. What I found was an exquisitely detailed account of the system's operation and development, written engagingly and with just the right amount of depth to prove that Redmond and Smith know what they're talking about.
Whirlwind and SAGE were mammoth military-industrial undertakings -- far riskier and more ambitious than anything the U.S. government has tackled in recent times. The pace of the entire project, from the initial design sketches to full-blown deployment in concrete bunkers throughout the U.S., seems fantastic compared to modern contractor boondoggles. The project closely followed its projected timeline, practically scheduling technological breakthroughs enroute to a finished, working system that provided air defense security for decades.
A classic example of the reach of Whirwind's designers was their decision to use magnetic core memory instead of williams tubes, mercury delay lines, or capacitive memory technologies. Immediately after deciding to use core memory, they set about inventing it so that it would be available for the first prototype machine, which was undergoing design in parallel with the memory development effort. As a result, Whirlwind's memory had unprecedented speed and reliability, and as a side effect core memory would dominate all commercial and government computer systems for the next twenty years.
Redmond and Smith provide wonderful insight into the obstacles SAGE developers encountered, with stories that any engineer will find fascinating. For instance, at an early stage of development the streams of radar data being sent to Whirwind for analysis are found to be full of noise and clutter, such as reflections from the ground and migratory flocks of birds. So Whirlwind software developers develop algorithms to filter out this signal trash, only to discover that the Whirlwind processor is far two slow to do both the filtering and its assigned job of sorting, tracking, and designating enemy targets. So SAGE designers push the clutter problem out to the radar signal delivery teams to deal with using analog filtering electronics, almost failing to notice that the science of digital signal processing had just been invented.
Together, Whirwind and SAGE advanced computer science by fifty years in just a handful of months. What drove this intense development? The arms race. Fear is a very good motivator, and in such competitive times, science and society seem to reap mass benefits that often go unnoticed.
As an aside, when my copy of the book arrived (I bought a used edition from an Amazon vendor), the bookseller had included a note apologizing for the scribbling on the inside front cover (the book was advertised in "new" condition). That "scribbling" turned out to be a personal note from author Kent Redmond to co-author Thomas Smith: "Tom, we did it!".
Eat your hearts out!
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