Classic Computing: SAGE Protected US From 1960s Invasions

Dag Spicer from the Computer History Museum leaned over and unscrewed a bolt. Underneath, it read, "I am Going Mad". The operator's job was to look for cold war bombers that never came. I would go mad, too. Look:

The IBM SAGE spoke to me. It was old, but unlike other machines from the era, with crude punch interfaces, it had a GUI, a light gun, and hell an ashtray. And a big yellow screen. The ashtray was so operators didn't have to leave their posts for cigarette breaks. Spotting incoming planes from the Soviet Union was precise work that needed constant attention.

You see, after World War II, it was believed that bombers were invincible; That their high altitude, distanced attacks from above and multiple engines would allow them to drop their deadly payloads and fly away without any resistance. It was believed that the only way to intercept these attacks was by having planes in the air at all times.

SAGE stood for Semi-Automatic Ground Environment and its sole purpose was to analyse radar data in real time and relay targeting information to fighter planes' autopilots. It was built by IBM in 1954 based off of MIT technology and was a forebearer of additional *amazing futuristic ideas* like magnetic core memory, networking, and modems to facilitate communication between the 27 bases. Each of those bases had a SAGE. And a backup that could be hot swapped. The entire system had a then impressive 99.6% uptime in an age when most computers would blow a vac tube at every day or so. The computer's console referred to a much larger back end that was 300 tons and took up an entire floor of a usually faceless concrete building. The software was written by the Rand corporation because IBM didn't know what they'd do with 2000 in house programmers after the project was done, something they admitted was a part of their historically out of touch vision of just how important programmers would eventually become to big blue. The code itself was 250,000 lines long. Nothing compared to a modern operating system on even your phone, but it was the most complex of its time, employing 20% of the world's programming force at the time.

What's sad is that these glorious machines, even at their best and earliest warnings of incoming missiles, would only be informing the United States of the inevitable: there wouldn't have been enough time to scramble jets and intercept a real threat, I would guess because the US is geographically too large to defend. Thank god for the great vastness of the Pacific, the Atlantic, Canada and Mexico.

The SAGE was retired in 1983 when ICBMs rendered them even more obsolete. But before then, adding shame to uselessness was the fact that in the end, the only place to get SAGE replacement tubes was from the Soviet Union itself. The industrial war machine is a complex and non nonsensical thing.

[Computer History Museum, Wikipedia] The Computer History Museum is a wonderful place. If you're in northern CA, I recommend you find a way to stop by. We'll be running pieces from their collection as an ongoing series. Special thanks to Fiona Tang, John Hollar and the amazing Dag Spicer for showing me around.

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